Protection of the brain & the spinal cord- (i) Bony outer covering: skull for the brain & vertebral column for the spinal cord. (ii) Cerebrospinal fluid present in between the three membranes. Action caused by Nervous tissue Information Nervous tissue Brain Muscles Causes action → → → Path or action- impulse Muscle cell Changes shape due to special proteins → → ↓ Action caused Shorter form of muscles Change shape & arrangement of cell ← ← Chemical communication by hormones- (advantages) Electrical impulses have limitations because they reach only those cells connected to the nervous tissue. Also the nerve cells cannot generate & transmit impulses continuously. communication is slower. Hormones- (i) are chemical messengers secreted by endocrine glands (ii) Are secreted in small amounts & may act in nearby places or distant places. Do not take part in the reaction & are destroyed immediately. Hormones are secreted by- Endocrine glands & Exocrine glands S. No. Endocrine glands Exocrine glands 1. Ducts absent present 2. Secrete hormones Secrete enzymes 3. Secreted in Secreted in ducts of glands 4. Situated away from the site of action Situated near the site of action Some glands which act as both endocrine & exocrine Gland Endocrine function Exocrine function Pancreas Produces insulin & Glucagon Produces digestive enzyme. (pancreatic hormone. amylase) Testes Produces hormone Produces male gametes (reproductive Testosterone Ovaries Produces hormone Oestrogen Produces female gametes (reproductive cells) Important Endocrine glands, the hormone they secrete & their function Refer to figure 7.7 page no. 124 of N.C.E.R.T Text book) Endocrine Hormone Function Pituitary gland Growth hormone Body growth, development of & muscles (If excess- Gigantism) (If less- Dwarfism)
Protection of the brain & the spinal cord- (i) Bony outer covering: skull for the brain & vertebral column for the spinal cord. (ii) Cerebrospinal fluid present in between the three membranes. Action caused by Nervous tissue Information → Nervous tissue → Brain Muscles → Causes action Path or action- impulse → Muscle cell → Changes shape due to special proteins ↓ Action caused ← Shorter form of muscles ← Change shape & arrangement of cell Chemical communication by hormones- (advantages) Electrical impulses have limitations because they reach only those cells connected to the nervous tissue. Also the nerve cells cannot generate & transmit impulses continuously. communication is slower. Hormones- (i) are chemical messengers secreted by endocrine glands (ii) Are secreted in small amounts & may act in nearby places or distant places. Do not take part in the reaction & are destroyed immediately. Hormones are secreted by- Endocrine glands & Exocrine glands S. No. Endocrine glands Exocrine glands 1. Ducts absent present 2. Secrete hormones Secrete enzymes 3. Secreted in Secreted in ducts of glands 4. Situated away from the site of action Situated near the site of action Some glands which act as both endocrine & exocrine Gland Endocrine function Exocrine function Pancreas Produces insulin & Glucagon hormone. Produces digestive enzyme. (pancreatic amylase) Testes Produces hormone Testosterone Produces male gametes (reproductive Ovaries Produces hormone Oestrogen Produces female gametes (reproductive cells) Important Endocrine glands, the hormone they secrete & their function Refer to figure 7.7 page no. 124 of N.C.E.R.T Text book) Endocrine Hormone Function Pituitary gland Growth hormone Body growth, development of & muscles (If excess- Gigantism) (If less- Dwarfism)
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