21. The adrenal medulla a. is stimulated by the sympathetic nervous system. b. produces epinephrine and norepinephrine. c. is stimulated when a person is physically excited. d. produces the "fight-or-flight" response. e. has all of these properties. 22. Parathyroid hormone (PTH) a. increases calcium level in the blood. b. inhibits the formation of active vitamin D in the kidneys. c. decreases the rate of bone breakdown. d. has an effect similar to that of calcitonin. e. has all of these characteristics. 23. Calcitonin a. is secreted by the parathyroid glands. b. increases the amount of calcium absorbed by the intestine. c. is synthesized by parafollicular cells of the thyroid gland. d. increases the rate of calcium release from bone. e. is secreted when blood calcium levels drop too low. 24. Hyperthyroidism a. can cause cretinism in infants. b. results in an elevated rate of metabolism. c. can cause extreme nervousness and chronic fatigue. d. would cause an increase in TSH secretion. e. both results in an elevated rate of metabolism and can cause extreme nervousness and chronic fatigue. 25. Prolactin a. helps development of, and production of milk in the breast. b. causes "milk letdown" from the breasts of lactating women. c. causes contraction of the muscle of the uterus. d. stimulates development of sperm cells in males. e. both causes "milk letdown" from the breasts of lactating women and causes contraction of the muscle of the uterus.
21. The adrenal medulla a. is stimulated by the sympathetic nervous system. b. produces epinephrine and norepinephrine. c. is stimulated when a person is physically excited. d. produces the "fight-or-flight" response. e. has all of these properties. 22. Parathyroid hormone (PTH) a. increases calcium level in the blood. b. inhibits the formation of active vitamin D in the kidneys. c. decreases the rate of bone breakdown. d. has an effect similar to that of calcitonin. e. has all of these characteristics. 23. Calcitonin a. is secreted by the parathyroid glands. b. increases the amount of calcium absorbed by the intestine. c. is synthesized by parafollicular cells of the thyroid gland. d. increases the rate of calcium release from bone. e. is secreted when blood calcium levels drop too low. 24. Hyperthyroidism a. can cause cretinism in infants. b. results in an elevated rate of metabolism. c. can cause extreme nervousness and chronic fatigue. d. would cause an increase in TSH secretion. e. both results in an elevated rate of metabolism and can cause extreme nervousness and chronic fatigue. 25. Prolactin a. helps development of, and production of milk in the breast. b. causes "milk letdown" from the breasts of lactating women. c. causes contraction of the muscle of the uterus. d. stimulates development of sperm cells in males. e. both causes "milk letdown" from the breasts of lactating women and causes contraction of the muscle of the uterus.