Physiology (Guyton & Hall) - Unit 14- Endocrinology and Reproduction (Chapters 75- 84)

84. Which finding is most likely in a patient who has myxedema? A) Somnolence B) Palpitations C) Increased respiratory rate D) Increased cardiac output E) Weight loss

84. A) Somnolence is a common feature of hypothyroidism. Palpitations, increased respiratory rate, increased cardiac output, and weight loss are all associated with hyperthyroidism.

55. Which hormone is largely unbound to plasma proteins? A) Cortisol B) T4 C) ADH D) Estradiol E) Progesterone

C) In general, peptide hormones are water soluble and are not highly bound by plasma proteins. ADH, a neurohypophysial peptide hormone, is virtually unbound by plasma proteins. In contrast, steroid and thyroid hormones are highly bound to plasma proteins.

24. Some cells secrete chemicals into the extracellular fluid that act on cells in the same tissue. Which of the following refers to this type of regulation? A) Neural B) Endocrine C) Neuroendocrine D) Paracrine E) Autocrine

24. D) Paracrine communication refers to cell secretions that diffuse into the extracellular fluid to affect neighboring cells. TMP13 p. 925

33. Which of the following is greater after birth than before birth? A) Flow through the foramen ovale B) Pressure in the right atrium C) Flow through the ductus arteriosus D) Aortic pressure

33. D) Because of the loss of blood flow through the placenta, systemic vascular resistance doubles at birth, which increases the aortic pressure as well as the pressure in the left ventricle and left atrium.

49. Negative feedback on FSH release from the anterior pituitary in men that results in a reduction in estradiol production is due to which hormone? A) Progesterone B) Estradiol C) Testosterone D) Inhibin

49. D) Inhibin prevents FSH release from the anterior pituitary, preventing Sertoli cells from causing aromatization to produce estradiol.

62. When compared with the postabsorptive state, which set of metabolic changes would most likely occur during the postprandial state? (see column)

62. D) After eating a meal, insulin secretion is increased. As a result, there is an increased rate of glucose uptake by both the liver and muscle. Insulin also inhibits hormone-sensitive lipase, which decreases hydrolysis of triglycerides in fat cells.

1. Which receptor controls nitric oxide (NO) release to cause vasodilation during penile erection? A) Leptin receptor B) Angiotensin AT1 receptor C) Endothelin ETA receptor D) Muscarinic receptor

1. D) Parasympathetic postganglionic fibers release acetylcholine that activates muscarinic receptors on endothelium to produce NO and increases cyclic guanosine monophosphate, which activates protein kinase G, causing a reduction in intracellular calcium (also increasing NO by positive feedback) and causing vasodilation. TMP13 p. 1027

10. Tecal cells in the follicle are not able to produce what sex steroid? A) Estradiol B) Testosterone C) Progesterone D) Dihydrotestosterone

10. A) Tecal cells do not have the capacity to produce estradiol because they lack aromatase. TMP13 pp. 1040, 1043, 1044

11. A baby is born with a penis, a scrotum with no testes, no vagina, and XX chromosomes. Tis condition is referred to as hermaphroditism. What could cause this abnormality? A) Abnormally high levels of human chorionic gonadotropin (HCG) production by the trophoblast cells B) Te presence of a testosterone-secreting tumor in the mother's right adrenal gland C) Abnormally high levels of LH in the maternal blood D) Abnormally low levels of testosterone in the maternal blood E) Abnormally low rates of estrogen production by the placenta

11. B) A very high concentration of testosterone in a female embryo will induce formation of male genitalia. An adrenal tumor in the mother that synthesizes testosterone at a high, uncontrolled rate could produce the masculinizing effect. TMP13 pp. 1043, 1044

12. A young woman is given daily injections of a substance beginning on the sixteenth day of her normal menstrual cycle and continuing for 3 weeks. As long as the injections continue, she does not menstruate. Te injected substance could be which of the following? A) Testosterone B) FSH C) An inhibitor of progesterone's actions D) A PGE2 inhibitor E) HCG

12. E) HCG has the same stimulatory effect as LH on the corpus luteum. Administration of HCG would cause the corpus luteum to continue to secrete estrogen and progesterone, preventing degradation of the endometrium and the onset of menstruation. TMP13 p. 1059

13. Which of the following increases secretion of GH? A) Senescence B) Insulin-like growth factor-1 (IGF-1) C) Somatostatin D) Hypoglycemia E) Exogenous GH administration

13. D) Hypoglycemia is a potent stimulus for GH. GH decreases with aging and in response to the hypothalamic inhibitory hormone somatostatin. GH secretion would decrease in response to both exogenous GH administration and IGF-1 as a result of negative feedback inhibition. TMP13 p. 945

14. Which of the following could inhibit the initiation of labor? A) Administration of an antagonist of the actions of progesterone B) Administration of LH C) Administration of an antagonist of PGE2 effects D) Mechanically dilating and stimulating the cervix E) Administration of oxytocin

14. C) Antagonism of progesterone's effects, dilation of the cervix, and oxytocin all increase uterine smooth muscle excitability and facilitate contractions and the onset of labor. LH would have no effect. Prostaglandin E2 strongly stimulates uterine smooth muscle contraction and is formed at an increasing rate by the placenta late in gestation. TMP13 p. 1064, 1066

15. Exposure to ultraviolet light directly facilitates which of the following? A) Conversion of cholesterol to 25-hydroxycholicalciferol B) Conversion of 25-hydroxycholicalciferol to 1,25- dihydroxycholicalciferol C) Transport of calcium into the extracellular fluid D) Formation of calcium-binding protein E) Storage of vitamin D3 in the liver

15. A) Ultraviolet light absorbed by the skin directly facilitates conversion of cholesterol to 25-hydroxycholesterol. TMP13 p. 1007

16. Which of the following decreases the pressure in the pulmonary artery after birth? A) An increase in systemic arterial pressure B) Closure of ductus arteriosus C) An increase in left ventricular pressure D) A decrease in pulmonary vascular resistance

16. D) Pulmonary vascular resistance greatly decreases as a result of expansion of the lungs. In the unexpanded fetal lungs, the blood vessels are compressed because of the small volume of the lungs. Immediately upon expansion, these vessels are no longer compressed, and the resistance to blood flow decreases severalfold. TMP13 pp. 1073, 1074

17. Which of the following is both synthesized and stored in the hypothalamus? A) ADH B) Tyroid-stimulating hormone (TSH) C) LH D) Somatostatin E) Somatomedin

17. D) Te inhibitory hormone somatostatin is both synthesized and stored in the hypothalamus. Both TSH and LH are synthesized and stored in the anterior pituitary gland. ADH is synthesized in the hypothalamus but is stored in the posterior pituitary gland. Somatomedin (IGF-1) is synthesized in the liver. TMP13 p. 946

18. If a radioimmunoassay is properly conducted and the amount of radioactive hormone bound to antibody is low, what would this result indicate? A) Plasma levels of endogenous hormone are high B) Plasma levels of endogenous hormone are low C) More antibody is needed D) Less radioactive hormone is needed

18. A) In a radioimmunoassay, there is too little antibody to completely bind the radioactively tagged hormone and the hormone in the fluid (plasma) to be assayed. Thus, there is competition between the labeled and endogenous hormone for binding sites on the antibody. Consequently, if the amount of radioactive hormone bound to antibody is low, this finding would indicate that plasma levels of endogenous hormone are high. TMP13 p. 936

23. What accompanies sloughing of the endometrium during the endometrial cycle in a normal woman? A) An increase in progesterone B) Te LH "surge" C) A decrease in both progesterone and estrogen D) An increase in estradiol

23. C) At the end of the luteal phase, the corpus luteum is resorbed and fails to produce progesterone and estradiol, making levels fall precipitously and causing the endometrium to slough. TMP13 p. 1039

19. By which mechanism do LH and FSH return to baseline levels? A) LH surge B) Negative feedback on gonadotropin-releasing hormone (GnRH) by progesterone C) Negative feedback on GnRH by estradiol D) Negative feedback on GnRH from testosterone

19. C) Just before the LH surge, estradiol levels increase, which causes negative feedback on GnRH to stop producing LH and FSH, resulting in the decrease in their levels. TMP13 p. 1039

2. Which statement about antidiuretic hormone (ADH) is true? A) It is synthesized in the posterior pituitary gland B) It increases salt and water reabsorption in the collecting tubules and ducts C) It stimulates thirst D) It has opposite effects on urine and plasma osmolality

2. D) ADH increases the permeability of the collecting tubules and ducts to water, but not to sodium, which in turn increases water reabsorption and decreases water excretion. As a result, urine concentration increases and the retained water dilutes the plasma. ADH is synthesized in the supraoptic and paraventricular nuclei of the hypothalamus and has no direct effect on the thirst center. TMP13 pp. 949-364, 404, 949

20. Spermatogenesis is regulated by a negative feedback control system in which FSH stimulates the steps in sperm cell formation. Which negative feedback signal associated with sperm cell production inhibits pituitary formation of FSH? A) Testosterone B) Inhibin C) Estrogen D) LH

20. B) Te Sertoli cells of the seminiferous tubules secrete inhibin at a rate proportional to the rate of production of sperm cells. Inhibin has a direct inhibitory effect on anterior pituitary secretion of FSH. FSH binds to specific receptors on the Sertoli cells, causing the cells to grow and secrete substances that stimulate sperm cell production. Te secretion of inhibin thereby provides the negative feedback control signal from the seminiferous tubules to the pituitary gland. TMP13 p. 1033

21. Which of the following is true during the 12-hour period preceding ovulation? A) A surge of LH is secreted from the pituitary B) Te surge occurs immediately after the formation of the corpus luteum C) Te surge is followed immediately by a fall in the plasma concentration of progesterone D) Te number of developing follicles is increasing

21. B) Ovulation will not take place unless a surge of LH precedes it. Immediately prior to ovulation, the number of follicles is decreasing due to normal attrition of all but one follicle, and consequently estrogen synthesis by the ovary is decreasing. Progesterone synthesis is stimulated by the LH surge. TMP13 pp. 1039, 1040

22. When do progesterone levels rise to their highest point during the female hormonal cycle? A) Between ovulation and the beginning of menstruation B) Immediately before ovulation C) When the blood concentration of LH is at its highest point D) When 12 primary follicles are developing to the antral stage

22. A) Te corpus luteum is the only source of progesterone production, except for minute quantities secreted from the follicle before ovulation. Te corpus luteum is functional between ovulation and the beginning of menstruation, during which time the concentration of LH is suppressed below the level achieved during the preovulatory LH surge. TMP13 pp. 1046-1047

25. Which of the following pairs is an example of the type of regulation referred to in Question 24? A) Somatostatin—GH secretion B) Somatostatin—insulin secretion C) Dopamine—prolactin secretion D) Norepinephrine—corticotropin-releasing hormone (CRH) secretion E) CRH—adrenocorticotropic hormone (ACTH) secretion

25. B) Te delta cells of the pancreas secrete somatostatin, which inhibits the secretion of insulin and glucagon from the pancreatic beta and alpha cells, respectively. Choice D is an example of neural communication, and the remaining choices are examples of neuroendocrine communication. TMP13 pp. 925, 993

26. A professional athlete in her mid-20s has not had a menstrual cycle for 5 years, although a bone density scan revealed normal skeletal mineralization. Which fact may explain these observations? A) She consumes a high-carbohydrate diet B) Her grandmother sustained a hip fracture at age 79 years C) Her blood pressure is higher than normal D) Her plasma estrogen concentration is very low E) She has been taking anabolic steroid supplements for 5 years

26. E) Anabolic steroids bind to testosterone receptors in the hypothalamus, providing feedback inhibition of normal ovarian cycling and preventing menstrual cycling as well as stimulation of osteoblastic activity in the bones. TMP13 pp. 1028, 1031

27. What is the nongenomic effect of testosterone on vascular smooth muscle? A) Vasodilation B) Vasoconstriction C) Increase in prostaglandins D) Increase in estrogen receptors

27. A) Testosterone causes vasodilation by inhibiting L-type calcium channels to inhibit calcium influx into the cells, thus causing vasodilation. TMP13 p. 1026

28. In the circulatory system of a fetus, which of the following is greater before birth than after birth? A) Arterial PO2 B) Right atrial pressure C) Aortic pressure D) Left ventricular pressure

28. B) Right atrial pressure falls dramatically after the onset of breathing because of a reduction in pulmonary vascular resistance, pulmonary arterial pressure, and right ventricular pressure. TMP13 pp. 1073-1075

29. A patient with Conn's syndrome.

29. E) Patients with Conn's syndrome have tumors of the zona glomerulosa that secrete large amounts of aldosterone. Consequently, plasma levels of aldosterone are elevated, causing hypokalemia. Te secretion of cortisol from the zona fasciculata is normal. TMP13 p. 981

3. After menopause, hormone replacement therapy with estrogen-like compounds is effective in preventing the progression of osteoporosis. What is the mechanism of their protective effect? A) Tey stimulate the activity of osteoblasts B) Tey increase absorption of calcium from the gastrointestinal tract C) Tey stimulate calcium reabsorption by the renal tubules D) Tey stimulate parathyroid hormone (PTH) secretion by the parathyroid gland

3. A) Estrogen compounds are believed to have an osteoblast-stimulating effect. When the amount of estrogen in the blood falls to very low levels after menopause, the balance between the bone-building activity of the osteoblasts and the bone-degrading activity of the osteoclasts is tipped toward bone degradation. When estrogen compounds are added as part of hormone replacement therapy, the bone-building activity of the osteoblasts is increased to balance the osteoclastic activity. TMP13 pp. 949, 1045

30. A patient consuming a low-sodium diet. (Picture)

30. D) Aldosterone secretion is elevated when dietary sodium intake is low, but cortisol secretion is normal. Although aldosterone increases the rate of potassium secretion by the principal cells of the collecting tubules, this effect is offset by a low distal tubular flow rate. Consequently, there is little change in either potassium excretion or plasma potassium concentration. TMP13 pp. 971-972

32. Which enzyme in the cytochrome P450 steroid synthesis cascade is directly responsible for estradiol synthesis? A) 17-beta-hydroxysteroid dehydrogenase B) 5-alpha reductase C) Aromatase D) Side chain cleavage enzyme

32. C) Aromatase causes conversion of testosterone to estradiol.

34. PTH does what directly? A) Controls the rate of 25-hydroxycholicalciferol formation B) Controls the rate of calcium transport in the mucosa of the small intestine C) Controls the rate of formation of calcium-binding protein D) Controls the rate of formation of 1,25-dihydroxycholicalciferol E) Stimulates renal tubular phosphate reabsorption

34. D) Parathyroid hormone acts in the renal cortex to stimulate the reaction forming 1,25-dihydroxycholicalciferol from 25-hydroxycholicalciferol. It has no effects on other the other reactions.

35. Which substances are most likely to produce the greatest increase in insulin secretion? A) Amino acids B) Amino acids and glucose C) Amino acids and somatostatin D) Glucose and somatostatin

35. B) Both amino acids and glucose stimulate insulin secretion. Furthermore, amino acids strongly potentiate the glucose stimulus for insulin secretion. Somatostatin inhibits insulin secretion.

36. Which of the following would be expected in a child with dwarfism due to pituitary dysfunction? (See column in the book)

36. F) In this form of dwarfism, there is decreased synthesis and secretion of GH into the circulation. As a result, stimulation of hepatic IGF-1 secretion is decreased and secretion of hypothalamic GnRH is increased due to diminished negative feedback. GH has several actions to increase blood levels of glucose, and when blood levels of GH are inappropriately low, fasting blood glucose concentration tends to fall.

37. For male differentiation to occur during embryonic development, testosterone must be secreted from the testes. What stimulates the secretion of testosterone during embryonic development? A) LH from the maternal pituitary gland B) HCG C) Inhibin from the corpus luteum D) GnRH from the embryo's hypothalamus

37. B) HCG also binds to LH receptors on the interstitial cells of the testes of the male fetus, resulting in the production of testosterone in male fetuses up to the time of birth. Tis small secretion of testosterone is what causes the fetus to develop male sex organs instead of female sex organs

38. A patient has an elevated plasma thyroxine (T4) concentration, a low plasma TSH concentration, and her thyroid gland is smaller than normal. What is the most likely explanation for these findings? A) A lesion in the anterior pituitary that prevents TSH secretion B) Te patient is taking propylthiouracil C) Te patient is taking thyroid extract D) Te patient is consuming large amounts of iodine E) Graves' disease

38. C) If a subject took sufficient amounts of exogenous thyroid extract to increase plasma levels of T4 above normal, feedback would cause the secretion of TSH to decrease. Low plasma levels of TSH would result in atrophy of the thyroid gland. In a person with Graves' disease, the same changes in plasma levels of T4 and TSH would be present, but the thyroid gland would not be atrophied. In fact, goiter is often present in patients with Graves' disease. A lesion in the anterior pituitary that prevents TSH secretion or the taking of propylthiouracil or large amounts of iodine would be associated with low plasma levels of T4.

39. Extracellular ionic calcium activity will be decreased within 1 minute by which of the following? A) An increase in extracellular phosphate ion activity B) An increase in extracellular pH C) A decrease in extracellular partial pressure of carbon dioxide (PCO2) D) All the above E) None of the above

39. D) Choices A to C would all shift the mass action balance toward the side favoring association of ionic calcium with phosphate compounds or other anionic compounds, resulting in reduced levels of free ionic calcium

63. Very early in embryonic development, testosterone is formed within the male embryo. What is the function of this hormone at this stage of development? A) Stimulation of bone growth B) Stimulation of development of male sex organs C) Stimulation of development of skeletal muscle D) Inhibition of LH secretion

63. B) Te primary function of testosterone in the embryonic development of males is to stimulate formation of the male sex organs.

4. A patient has nephrogenic diabetes insipidus. Of the following options, which outcome would be expected or which intervention would be suggested? A) Expected outcome: decreased plasma sodium concentration B) Expected outcome: increased secretion of ADH from the supraoptic and paraventricular nuclei C) Expected outcome: high urine osmolality D) Suggested intervention: water restriction E) Suggested intervention: ADH antagonists (vaptans)

4. B) In nephrogenic diabetes insipidus, the kidneys cannot respond to ADH. Consequently, dilute urine and loss of water from the extracellular fluid occurs, resulting in hypernatremia. Hypernatremia stimulates thirst, which attenuates the severity of hypernatremia, whereas water restriction exacerbates hypernatremia. Hypernatremia also stimulates ADH secretion from the magnocellular neurons in the hypothalamus. TMP13 p. 949

40. As menstruation ends, estrogen levels in the blood rise rapidly. What is the source of the estrogen? A) Corpus luteum B) Developing follicles C) Endometrium D) Stromal cells of the ovaries E) Anterior pituitary gland

40. B) In the nonpregnant female, the only significant source of estrogen is ovarian follicles or corpus luteae. Menstruation begins when the corpus luteum degenerates. Menstruation ends when developing follicles secrete estrogen sufficiently to raise circulating concentration to a level that stimulates regrowth of the endometrium

41. A 30-year-old woman reports to the clinic for a routine physical examination. Te examination reveals she is pregnant. Her plasma levels of TSH are high, but her total thyroid hormone concentration is normal. Which of the following best reflects the patient's clinical state? A) Graves' disease B) Hashimoto's disease C) A pituitary tumor secreting TSH D) A hypothalamic tumor secreting thyrotropinreleasing hormone (TRH) E) Te patient is taking thyroid extract

41. B) As a result of negative feedback, plasma levels of TSH are a sensitive index of circulating levels of unbound (free) thyroid hormones. High plasma levels of TSH indicate inappropriately low levels of free thyroid hormones in the circulation, such as are present with autoimmune destruction of the thyroid gland in persons with Hashimoto's disease. However, because elevated plasma levels of estrogen in pregnancy increase hepatic production of TBG, the total amount (bound + free) of thyroid hormones in the circulation is elevated. Plasma levels of thyroid hormones are elevated in persons with Graves' disease and in patients with a pituitary TSH-secreting tumor, as well in patients given thyroid extract for therapy.

42. Which anterior pituitary hormone plays a major role in the regulation of a nonendocrine target gland? A) ACTH B) TSH C) Prolactin D) FSH E) LH

42. C) Te major target tissue for prolactin is the breast, where it stimulates the secretion of milk. Te other anterior pituitary hormones (ACTH, TSH, FSH, and LH) stimulate hormones from endocrine glands

43. A female athlete who took testosterone-like steroids for several months stopped having normal menstrual cycles. What is the best explanation for this observation? A) Testosterone stimulates inhibin production from the corpus luteum B) Testosterone binds to receptors in the endometrium, resulting in the failure of the endometrium to develop during the normal cycle C) Testosterone binds to receptors in the anterior pituitary that stimulate the secretion of FSH and LH D) Testosterone inhibits the hypothalamic secretion of GnRH and the pituitary secretion of LH and FSH

43. D) Te cells of the anterior pituitary that secrete LH and FSH, along with the cells of the hypothalamus that secrete GnRH, are inhibited by both estrogen and testosterone. Te steroids taken by the woman caused sufficient inhibition to result in cessation of the monthly menstrual cycle.

44. An experiment is conducted in which ADH is administered at hour 3 to four subjects (A to D). In the above figure, which lines most likely reflect the response to ADH administration in a normal patient and in a patient with central diabetes insipidus? (see picture and column in the book)

44. D) Patients with central diabetes insipidus have an inappropriately low secretion rate of ADH in response to changes in plasma osmolality, but their renal response to ADH is not impaired. Because plasma levels of ADH are depressed, the ability to concentrate urine is impaired, and a large volume of dilute urine is excreted. Loss of water tends to increase plasma osmolality, which stimulates the thirst center and leads to a very high rate of water turnover.

45. Which of the following decreases the resistance in the arteries leading to the sinuses of the penis? A) Stimulation of the sympathetic nerves innervating the arteries B) NO C) Inhibition of activity of the parasympathetic nerves leading to the arteries D) All the above

45. B) NO is the vasodilator that is normally released, causing vasodilation in these arteries

46. A patient has a goiter associated with high plasma levels of both TRH and TSH. Her heart rate is elevated. Tis patient most likely has which condition? A) An endemic goiter B) A hypothalamic tumor secreting large amounts of TRH C) A pituitary tumor secreting large amounts of TSH D) Graves' disease

46. B) A hypothalamic tumor secreting large amounts of TRH would stimulate the pituitary gland to secrete increased amounts of TSH. As a result, the secretion of thyroid hormones would increase, which would result in an elevated heart rate. In comparison, a patient with either a pituitary tumor secreting large amounts of TSH or Graves' disease would have low plasma levels of TRH because of feedback. Both TRH and TSH levels would be elevated in an endemic goiter, but the heart rate would be depressed because of the low rate of T4 secretion.

47. A man eats a low-carbohydrate meal that is rich in proteins containing the amino acids that stimulate insulin secretion. Which response accounts for the absence of hypoglycemia? A) Suppression of GH B) Suppression of somatomedin C secretion C) Stimulation of cortisol secretion D) Stimulation of glucagon secretion E) Stimulation of epinephrine secretion

47. D) Consumption of amino acids stimulates both GH and glucagon secretion. Increased glucagon secretion tends to increase blood glucose concentration and thus opposes the effects of insulin to cause hypoglycemia

48. A 46-year-old man has "puffy" skin and is lethargic. His plasma TSH concentration is low and increases markedly when he is given TRH. What is the most likely diagnosis? A) Hyperthyroidism due to a thyroid tumor B) Hyperthyroidism due to an abnormality in the hypothalamus C) Hypothyroidism due to an abnormality in the thyroid D) Hypothyroidism due to an abnormality in the hypothalamus E) Hypothyroidism due to an abnormality in the pituitary

48. D) Lethargy and myxedema are signs of hypothyroidism. Low plasma levels of TSH indicate that the abnormality is in either the hypothalamus or the pituitary gland. Te responsiveness of the pituitary to the administration of TRH suggests that pituitary function is normal and that the hypothalamus is producing insufficient amounts of TRH.

5. Within minutes after a normal delivery, flow through the foramen ovale decreases dramatically. What is the cause of this change? A) Increased formation of prostaglandin E2 (PGE2) in the endocardium B) Increased rate of flow through the pulmonary artery C) Increased left atrial pressure D) Increased right atrial pressure E) Increased partial pressure of oxygen (PO2)

5. C) After birth, systemic arterial resistance increases dramatically due to loss of the placental vasculature. Consequently, arterial pressure, left ventricular pressure, and left atrial pressure all increase. At the same time, pulmonary vascular resistance decreases due to expansion of the lungs, and pulmonary artery pressure, right ventricular pressure, and right atrial pressure all fall. Blood flow through the foramen is a function of the pressure gradient, which after birth favors flow from the left to the right atrium, but most of the flow is blocked by the septal flap on the septal wall of the left atrium. TMP13 pp. 1073-1075

50. During the first few years after menopause, FSH levels are normally extremely high. A 56-year-old woman completed menopause 3 years ago. However, she is found to have low levels of FSH in her blood. What is the best explanation for this finding? A) She has been receiving hormone replacement therapy with estrogen and progesterone since she completed menopause B) Her adrenal glands continue to produce estrogen C) Her ovaries continue to secrete estrogen D) She took birth control pills for 20 years before menopause

50. A) After menopause, the absence of feedback inhibition by estrogen and progesterone results in extremely high rates of FSH secretion. Women taking estrogen as part of hormone replacement therapy for symptoms associated with postmenopausal conditions have suppressed levels of FSH as a result of the inhibitory effect of estrogen.

51. Blockade of what receptors will prolong erection in the male? A) Estrogen receptors B) Cholesterol receptors C) Muscarinic receptors D) Phosphodiesterase-5 receptors

51. D) Phosphodiesterase-5 receptors prevent hydrolysis of cyclic guanosine monophosphate, thus keeping the levels high and maintaining vasodilation.

52. Which of the following pairs of hormones and the corresponding action is incorrect? A) Glucagon—increased glycogenolysis in liver B) Glucagon—increased glycogenolysis in skeletal muscle C) Glucagon—increased gluconeogenesis D) Cortisol—increased gluconeogenesis E) Cortisol—decreased glucose uptake in muscle

52. B) Glucagon stimulates glycogenolysis in the liver, but it has no physiological effects in muscle. Both glucagon and cortisol increase gluconeogenesis, and cortisol impairs glucose uptake by muscle.

53. A large dose of insulin is administered intravenously to a patient. Which set of hormonal changes is most likely to occur in the plasma in response to the insulin injection? (see column)

53. C) Injection of insulin leads to a decrease in blood glucose concentration. Hypoglycemia stimulates the secretion of GH, glucagon, and epinephrine, all of which have counter-regulatory effects to increase glucose levels in the blood.

54. What is a frequent cause of delayed breathing at birth? A) Fetal hypoxia during the birth process B) Maternal hypoxia during the birth process C) Fetal hypercapnia D) Maternal hypercapnia

54. A) Prolonged fetal hypoxia during delivery can cause serious depression of the respiratory center. Hypoxia may occur during delivery because of compression of the umbilical cord, premature separation of the placenta, excessive contraction of the uterus, or excessive anesthesia of the mother.

56. What is the mechanism by which the zona pellucida becomes "hardened" after penetration of a sperm cell to prevent a second sperm from penetrating? A) A reduction in estradiol B) Te proteins released from the acrosome of the sperm C) An increase in intracellular calcium in the oocyte D) An increase in testosterone that affects the sperm

56. What is the mechanism by which the zona pellucida becomes "hardened" after penetration of a sperm cell to prevent a second sperm from penetrating? A) A reduction in estradiol B) Te proteins released from the acrosome of the sperm C) An increase in intracellular calcium in the oocyte D) An increase in testosterone that affects the sperm

57. Why is milk produced by a woman only after delivery, not before? A) Levels of LH and FSH are too low during pregnancy to support milk production B) High levels of progesterone and estrogen during pregnancy suppress milk production C) Te alveolar cells of the breast do not reach maturity until after delivery D) High levels of oxytocin are required for milk production to begin, and oxytocin is not secreted until the baby stimulates the nipple

57. B) Although estrogen and progesterone are essential for the physical development of the breast during pregnancy, a specific effect of both these hormones is to inhibit the actual secretion of milk. Even though prolactin levels are increased 10- to 20-fold at the end of pregnancy, the suppressive effects of estrogen and progesterone prevent milk production until after the baby is born. Immediately after birth, the sudden loss of both estrogen and progesterone secretion from the placenta allows the lactogenic effect of prolactin to promote milk production.

58. Which of the following increases the rate of excretion of calcium ions by the kidney? A) A decrease in calcitonin concentration in the plasma B) An increase in phosphate ion concentration in the plasma C) A decrease in the plasma level of PTH D) Metabolic alkalosis

58. C) Te concentration of PTH strongly regulates the absorption of calcium ion from the renal tubular fluid. A reduction in hormone concentration reduces calcium reabsorption and increases the rate of calcium excretion in the urine. Te other choices either have little effect on or decrease calcium excretion.

59. A patient has hyperthyroidism due to a pituitary tumor. Which set of physiological changes would be expected? (see column)

59. B) A pituitary tumor secreting increased amounts of TSH would be expected to stimulate the thyroid gland to secrete increased amounts of thyroid hormones. TSH stimulates several steps in the synthesis of thyroid hormones, including the synthesis of thyroglobulin. Increased heart rate is among the many physiological responses to high plasma levels of thyroid hormones. However, high plasma levels of thyroid hormones do not cause exophthalmos. Immunoglobulins cause exophthalmos in Graves' disease, the most common form of hyperthyroidism.

6. Which hormones antagonize the effect of NO and cause the penis to become flaccid after orgasm? A) Endothelin and norepinephrine B) Estrogen and progesterone C) Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) D) Progesterone and LH

6. A) Norepinephrine is released from the nerve terminals and endothelin is released from endothelial cells in the vasculature, causing vasoconstriction of the vasculature. TMP13 p. 1027

60. A 25-year-old man is severely injured when hit by a speeding vehicle and loses 20 percent of his blood volume. Which set of physiological changes would be expected to occur in response to the hemorrhage? (see column)

60. A) Hemorrhage decreases the activation of stretch receptors in the atria and arterial baroreceptors. Decreased activation of these receptors increases ADH secretion.

61. If a woman has a tumor that is secreting large amounts of estrogen from the adrenal gland, which of the following will occur? A) Progesterone levels in the blood will be very low B) Her LH secretion rate will be totally suppressed C) She will not have normal menstrual cycles D) Her bones will be normally calcified E) All the above

61. E) Choices A to D are true: LH secretion will be suppressed (B) by the negative feedback effect of the estrogen from the tumor; consequently, she will not have menstrual cycles (C), and because she will not have normal cycles, no corpus luteae will develop, so no progesterone will be formed (A). Te high levels of estrogen produced by the tumor will provide stimulation of osteoblastic activity to maintain normal bone activity (D).

64. Which change would be expected to occur with increased binding of a hormone to plasma proteins? A) Increase in plasma clearance of the hormone B) Decrease in half-life of the hormone C) Increase in hormone activity D) Increase in degree of negative feedback exerted by the hormone E) Increase in plasma reservoir for rapid replenishment of free hormone

64. E) Protein-bound hormones are biologically inactive and cannot be metabolized. Tus, an increase in protein binding would tend to decrease hormone activity and plasma clearance and increase the half-life of the hormone. Free hormone is also responsible for negative feedback inhibition of hormone secretion. Terefore, a sudden increase in hormone binding to plasma proteins would decrease negative feedback. Protein binding of hormones does, however, provide a reservoir for the rapid replacement of free hormone.

65. A patient arrives in the emergency department apparently in cardiogenic shock due to a massive heart attack. His initial arterial blood sample reveals the following concentrations of ions and pH level: Sodium 137 mmol/L Bicarbonate 14 mmol/L Free calcium 2.8 mmol/L Potassium 4.8 mmol/L pH 7.16 To correct the acidosis, the attending physician begins an infusion of sodium bicarbonate and after 1 hour obtains another blood sample, which reveals the following values: Sodium 138 mmol/L Bicarbonate 22 mmol/L Free calcium 2.3 mmol/L Potassium 4.5 mmol/L pH 7.34 What is the cause of the decrease in calcium ion concentration? A) Te increase in arterial pH resulting from the sodium bicarbonate infusion inhibited PTH secretion B) Te increase in pH resulted in the stimulation of osteoblasts, which removed calcium from the circulation C) Te increase in pH resulted in an elevation in the concentration of HPO4 −, which shifted the equilibrium between HPO4 − and Ca++ toward CaHPO4 D) Te increase in arterial pH stimulated the formation of 1,25-dihydroxycholecalciferol, which resulted in an increased rate of absorption of calcium from the gastrointestinal tract

65. C) Te reduction in hydrogen ion indicated by the elevation in pH increases the concentration of negatively charged phosphate ion species available for ionic combination with calcium ions. Consequently, the free calcium ion concentration is reduced.

66. A patient presents with tachycardia and heat intolerance. You suspect Graves' disease. Which of the following is not consistent with your diagnosis? A) Increased total and free T4 B) Suppressed plasma [TSH] C) Exophthalmos D) Goiter E) Decreased thyroid radioactive iodine uptake

66. E) In Graves' disease, antibodies against the TSH receptor in the thyroid gland stimulate many of the steps in the synthesis of thyroid hormones, including increased iodine uptake. Due to excessive stimulation of the gland, the thyroid gland hypertrophies and secretes increased amounts of thyroid hormones. High circulating levels of thyroid hormones inhibit TSH secretion due to negative feedback inhibition. Te antibodies present in Graves' disease also cause pathological changes in the tissue surrounding the eyes, leading to protrusion of the eyeballs.

67. A 30-year-old woman is breastfeeding her infant. During suckling, which hormonal response is expected in the woman? A) Increased secretion of ADH from the supraoptic nuclei B) Increased secretion of ADH from the paraventricular nuclei C) Increased secretion of oxytocin from the paraventricular nuclei D) Decreased secretion of neurophysin E) Increased plasma levels of both oxytocin and ADH

67. C) During suckling, stimulation of receptors on the nipples increases neural input to both the supraoptic and paraventricular nuclei. Activation of these nuclei leads to the release of oxytocin and neurophysin from secretion granules in the posterior pituitary gland. Suckling does not stimulate the secretion of appreciable amounts of ADH.

68. A 30-year-old man has Conn's syndrome. Which set of physiological changes is most likely to occur in this patient compared with a healthy person? (see column)

68. C) In Conn's syndrome, large amounts of aldosterone are secreted. Because aldosterone causes sodium retention, hypertension is a common finding in patients with this condition. However, the degree of sodium retention is modest, as is the resultant increase in extracellular fluid volume. Tis occurs because the rise in arterial pressure offsets the sodium-retaining effects of aldosterone, limiting sodium retention and permitting daily sodium balance to be achieved.

69. Why is it important to feed newborn infants every few hours? A) Te hepatic capacity to store and synthesize glycogen and glucose is not adequate to maintain the plasma glucose concentration in a normal range for more than a few hours after feeding B) If adequate fluid is not ingested frequently, the plasma protein concentration will rise to greater than normal levels within a few hours C) Te function of the gastrointestinal system is poorly developed and can be improved by keeping food in the stomach at all times D) Te hepatic capacity to form plasma proteins is minimal and requires the constant availability of amino acids from food to avoid hypoproteinemic edema

69. A) Because the liver functions imperfectly during the first weeks of life, the glucose concentration in the blood is unstable and falls to very low levels within a few hours after feeding.

(Picture) The red lines in the above figure illustrate the normal relationships between plasma insulin concentration and glucose production in the liver and between plasma insulin concentration and glucose uptake in muscle. Use this figure to answer Questions 7-9. 7. Which lines most likely illustrate these relationships in a patient with type 2 diabetes? A) A and C B) A and D C) B and C D) B and D

7. C) Type 2 DM is characterized by diminished sensitivity of target tissues to the metabolic effects of insulin—that is, there is insulin resistance. As a result, hepatic uptake of glucose is impaired and glucose release is enhanced. In muscle, the uptake of glucose is impaired. TMP13 pp. 985-986, 995

70. Dehydroepiandrosterone sulfate (DHEAS), the precursor for the high levels of estradiol that occur in pregnancy, is made in what tissue? A) Fetal adrenal gland B) Ovary of the mother C) Placenta D) Adrenal gland of the mother

70. D) DHEA sulfate produced by the fetal adrenal gland diffuses to the placenta and is converted to DHEA and then to estradiol and provides estradiol to the mother.

71. What is the consequence of sporadic nursing of the neonate by the mother? A) An increase in prolactin-releasing hormone B) An increase in oxytocin C) Lack of birth control D) Lack of prolactin surge

71. D) Sporadic nursing of the mother results in a lack of prolactin surge because mechanosensors in the nipple cause prolactin release. Without prolactin release, there is a lack of milk production, and the mother eventually will not be able to provide milk for the baby.

83. Which of the following is higher in the neonate than in the fetus? A) Flow through the foramen ovale B) Right atrial pressure C) Flow through the ductus arteriosus D) Aortic pressure

83. B) Aortic pressure increases due to the increase in left ventricular pressure. Te increase in left atrial pressure causes the foramen ovale to close. Te ductus arteriosus also closes within a short time after birth.

72. Which of the following would be associated with parallel changes in aldosterone and cortisol secretion? A) Addison's disease B) Cushing's disease C) Cushing's syndrome (adrenal tumor) D) A low-sodium diet E) Administration of a converting enzyme inhibitor

72. A) Persons with Addison's disease have diminished secretion of both glucocorticoids (cortisol) and mineralocorticoids (aldosterone). In persons with Cushing's disease or Cushing's syndrome, cortisol secretion is elevated but aldosterone secretion is normal. A lowsodium diet is associated with a high rate of aldosterone secretion but a secretion rate of cortisol that is normal. By inhibiting the generation of angiotensin II and thus the stimulatory effects of angiotensin II on the zona glomerulosa, administration of a converting enzyme inhibitor would decrease aldosterone secretion without altering the rate of cortisol secretion.

73. A chronic increase in the plasma concentration of thyroxine-binding globulin (TBG) would result in which of the following? A) An increased delivery of T4 to target cells B) A decrease in plasma free [T4] C) An increase in the conversion of T4 to triiodothyronine (T3) in peripheral tissues D) An increase in TSH secretion E) No change in metabolic rate

73. E) In the steady state, high plasma levels of TBG would simply increase the reservoir for hormone and, therefore, the total amount of thyroid hormone in the circulation. However, protein-bound hormone is inactive. Te metabolic effects of thyroid hormones and their feedback inhibition on TSH secretion are determinedby the free thyroid hormone and not the total amount of thyroid hormone in the circulation. Both the plasma levels of free thyroid hormone and TSH would be expected to be normal in the steady state. Consequently, the metabolic rate would be unchanged.

74. RU486 causes abortion if it is administered before or soon after implantation. What is the specific effect of RU486? A) It binds to LH receptors, stimulating the secretion of progesterone from the corpus luteum B) It blocks progesterone receptors so that progesterone has no effect within the body C) It blocks the secretion of FSH by the pituitary D) It blocks the effects of oxytocin receptors in the uterine muscle

74. B) Progesterone is required to maintain the decidual cells of the endometrium. If progesterone levels fall, as they do during the last days of a nonpregnant menstrual cycle, menstruation will follow within a few days, with loss of pregnancy. Administration of a compound that blocks the progesterone receptor during the first few days after conception will terminate the pregnancy.

75. A 55-year-old man has developed the syndrome of inappropriate antidiuretic hormone secretion due to carcinoma of the lung. Which physiological response would be expected? A) Increased plasma osmolality B) Inappropriately low urine osmolality (relative to plasma osmolality) C) Increased thirst D) Decreased secretion of ADH from the pituitary gland

75. D) An inappropriately high rate of ADH secretion from the lung promotes excess water reabsorption, which tends to produce concentrated urine and a decrease in plasma osmolality. Low plasma osmolality suppresses both thirst and ADH secretion from the pituitary gland.

76. During pregnancy, the uterine smooth muscle is quiescent. During the ninth month of gestation, the uterine muscle becomes progressively more excitable. What factor contributes to the increase in excitability? A) Placental estrogen synthesis rises to high rates B) Progesterone synthesis by the placenta decreases C) Uterine blood flow reaches its highest rate D) PGE2 synthesis by the placenta decreases E) Activity of the fetus falls to low levels

76. B) A very high plasma concentration of progesterone maintains the uterine muscle in a quiescent state during pregnancy. In the final month of gestation the concentration of progesterone begins to decline, increasing the excitability of the muscle.

77. A 20-year-old woman is not having menstrual cycles. Her plasma progesterone concentration is found to be minimal. What is the explanation for the low level of progesterone? A) LH secretion rate is elevated B) LH secretion rate is suppressed C) FSH secretion rate is suppressed D) No corpus luteum is present E) High inhibin concentration in the plasma has suppressed progesterone synthesis

77. D) Te corpus luteum is the only source of progesterone. If she is not having menstrual cycles, no corpus luteum is present.

78. Before the preovulatory surge in LH, granulosa cells of the follicle secrete which hormone? A) Testosterone B) Progesterone C) Estrogen D) Inhibin

78. C) FSH stimulates the granulosa cells of the follicle to secrete estrogen.

Questions 79 and 80 - see graph and columns 79. Based on the above figure, which set of curves most likely reflects the responses in a healthy individual and in patients with type 1 or type 2 diabetes mellitus (DM)?

79. E) In response to increased blood levels of glucose, plasma insulin concentration normally increases during the 60-minute period following oral intake of glucose. In type 1 DM, insulin secretion is depressed. In contrast, in type 2 DM, insulin resistance is a common finding and, at least in the early stages of the disease, there is an abnormally high rate of insulin secretion.

8. Which lines most likely illustrate these relationships in a patient with acromegaly? A) A and C B) A and D C) B and C D) B and D (Picture)

8. C) In acromegaly, high plasma levels of GH cause insulin resistance. Consequently, glucose production by the liver is increased and glucose uptake by peripheral tissues is impaired. TMP13 pp. 943-944, 996-997

Questions 79 and 80 - see graph and columns 80. Based on the above figure, which set of curves most likely reflects the responses in a healthy person and in a patient in the early stages of Cushing's syndrome?

80. D) In Cushing's syndrome, high plasma levels of cortisol impair glucose uptake in peripheral tissues, which tends to increase plasma levels of glucose. As a result, the insulin response to oral intake of glucose is enhanced.

81. Which hormone activates enzyme-linked receptors? A) ADH B) Insulin C) ACTH D) PTH E) Aldosterone

81. B) In general, protein hormones cause physiological effects by binding to receptors on the cell membrane. However, of the four protein hormones indicated, only insulin activates an enzyme-linked receptor. Aldosterone is a steroid hormone and enters the cytoplasm of the cell before binding to its receptor.

82. Which of the following is produced by the trophoblast cells during the first 3 weeks of pregnancy? A) Estrogen B) LH C) Oxytocin D) HCG E) None of the above

82. D) HCG is secreted from the trophoblast cells beginning shortly after the blastocyst implants in the endometrium.

85. At birth, a large, well-nourished baby is found to have a plasma glucose concentration of 17 mg/dl (normal is 80 to 100 mg/dl) and a plasma insulin concentration twice the normal value. What is the explanation for these findings? A) Te neonate experienced in utero malnutrition B) Te mother was malnourished during pregnancy C) The mother is diabetic, with poorly controlled hyperglycemia D) Te mother is obese

85. C) An infant born of an untreated diabetic mother will have considerable hypertrophy and hyperfunction of the islets of Langerhans in the pancreas. As a consequence, the infant's blood glucose concentration may fall to lower than 20 mg/dl shortly after birth.

86. In the fetus, why can normal growth occur despite low PO2 levels? A) Te concentration of hemoglobin A is increased in the fetus B) Te hemoglobin of the fetus can carry more oxygen at lower PCO2 levels C) Te oxyhemoglobin curve in the fetus is shifted to the left D) Te mother has increased blood volume during pregnancy

86. C) Hemoglobin F levels are higher in the fetus than in the mother, and hemoglobin F in the fetus can carry more oxygen than can hemoglobin in the mother.

87. Which of the following stimulates the secretion of PTH? A) An increase in extracellular calcium ion activity above the normal value B) An increase in calcitonin concentration C) Respiratory acidosis D) Increased secretion of PTH-releasing hormone from the hypothalamus E) None of the above

87. E) Choices A to D would not stimulate PTH secretion. An increase in calcium concentration (A) suppresses PTH secretion; calcitonin has little to no effect on PTH secretion (B); acidosis would increase free calcium in the extracellular fluid, thereby inhibiting PTH secretion (C); and PTH-releasing hormone does not exist (D).

88. A 40-year-old woman consumes a high-potassium diet for several weeks. Which hormonal change is most likely to occur? A) Increased secretion of DHEA B) Increased secretion of cortisol C) Increased secretion of aldosterone D) Increased secretion of ACTH E) Decreased secretion of CRH

88. C) Potassium is a potent stimulus for aldosterone secretion, as is angiotensin II. Terefore, a patient consuming a high-potassium diet would exhibit high circulating levels of aldosterone.

89. After implantation into the uterus, nutrition of the blastocyst comes from which structure? A) Placenta B) Decidua C) Glomerulosa cells D) Corpus luteum

89. B) Te decidua and trophoblasts provide the nutrition needed to provide nourishment of the blastocyst.

9. Line D most likely illustrates the influence of which of the following? A) Exercise B) Obesity C) Growth hormone (GH) D) Cortisol E) Glucagon (Picture)

9. A) During exercise, glucose utilization by muscle is increased, which is largely independent of insulin. TMP13 p. 985

90. Which hormone is not stored in its endocrine-producing gland? A) T4 B) PTH C) Aldosterone D) ACTH E) Insulin

90. C) Steroid hormones are not stored to any appreciable extent in their endocrine producing glands. Tis is true for aldosterone, which is produced in the adrenal cortex. In contrast, there are appreciable stores of thyroid hormones and peptide hormones in their endocrine-producing glands.

91. A young woman comes to the emergency department with a vertebral compression fracture. Radiographs of the spine indicate generalized demineralization. She is vegetarian, does not smoke or drink alcohol, and has a normal plasma potassium concentration of 5.4 mEq/L, a sodium concentration of 136 mEq/L, and a plasma calcium concentration of 7.0 mg/dl. Her vitamin D3 value is several times greater than normal, although her 1,25-dihydroxycholecalciferol concentration is at the lower limit of detectability. She has been in renal failure for the past 5 years and undergoes hemodialysis three times each week. What is the cause of her low 1,25-dihydroxycholecalciferol level? A) Metabolic acidosis B) Metabolic alkalosis C) She is unable to form 1,25-dihydroxycholecalciferol because of her extensive kidney disease D) She is undergoing dialysis with a dialysis fluid that does not contain calcium E) She is taking receiving calcium supplements

91. C) 1,25-dihydroxycholecalciferol is formed only in the renal cortex. Extensive renal disease reduces the amount of cortical tissue, eliminating the source of this active calcium regulating hormone.

92. Te placenta is incapable of synthesizing which hormones? A) Estrogen B) Progesterone C) Androgens D) Estriol

92. C) Te placenta cannot produce androgens but can only produce DHEA by removal of the sulfate from DHEAS produced in the fetal adrenal glands.

93. A neonate develops jaundice and has a bilirubin concentration of 10 mg/dl on day 2 (normal is 3 mg/dl at 2 days old). Te neonatologist can be confident that the condition is not erythroblastosis fetalis if which of the following is true? A) Te bilirubin concentration rises no further B) Hematocrit falls only slightly C) Te mother, father, and neonate are all Rh-negative D) Te mother has no history of hepatic dysfunction

93. C) For erythroblastosis fetalis to occur, the baby must inherit Rh-positive red blood cells from the father. If the mother is Rh-negative, she then becomes immunized against the Rh-positive antigen in the red blood cells of the fetus, and her antibodies destroy fetal red blood cells, releasing large quantities of bilirubin into the plasma of the fetus.

94. Which finding would likely be reported in a patient with a deficiency in iodine intake? A) Weight loss B) Nervousness C) Increased sweating D) Increased synthesis of thyroglobulin E) Tachycardia

94. D) Because iodine is needed to synthesize thyroid hormones, the production of thyroid hormones is impaired if iodine is deficient. As a result of feedback, plasma levels of TSH increase and stimulate the follicular cells to increase the synthesis of thyroglobulin, which results in a goiter. Increased metabolic rate, sweating, nervousness, and tachycardia are all common features of hyperthyroidism, not hypothyroidism, due to iodine deficiency.

95. A 37-year-old woman presents to her physician with an enlarged thyroid gland and high plasma levels of T4 and T3. Which of the following is likely to be decreased? A) Heart rate B) Cardiac output C) Peripheral vascular resistance D) Ventilation rate E) Metabolic rate

95. C) Because of the effects of thyroid hormones to increase metabolism in tissues, tissues vasodilate, thus increasing blood flow and cardiac output. All the other choices increase in response to high plasma levels of thyroid hormones.

96. Before intercourse, a woman irrigates her vagina with a solution that lowers the pH of the vaginal fluid to 4.5. What will be the effect on sperm cells in the vagina? A) Te metabolic rate will increase B) Te rate of movement will decrease C) Te formation of PGE2 will increase D) Te rate of oxygen consumption will increase

96. B) Sperm cell motility decreases as pH is reduced below 6.8. At a pH of 4.5, sperm cell motility is significantly reduced. However, the buffering effect of sodium bicarbonate in the prostatic fluid raises the pH somewhat, allowing the sperm cells to regain some mobility.

97. Which hormonal responses would be expected after a meal high in protein? (see column)

97. B) A protein meal stimulates all three hormones indicated.

98. Men who take large doses of testosterone-like androgenic steroids for long periods are sterile in the reproductive sense of the word. What is the explanation for this finding? A) High levels of androgens bind to testosterone receptors in the Sertoli cells, resulting in overstimulation of inhibin formation B) Overstimulation of sperm cell production results in the formation of defective sperm cells C) High levels of androgen compounds inhibit the secretion of GnRH by the hypothalamus, resulting in the inhibition of LH and FSH release by the anterior pituitary D) High levels of androgen compounds produce hypertrophic dysfunction of the prostate gland

98. C) Testosterone secreted by the testes in response to LH inhibits hypothalamic secretion of GnRH, thereby inhibiting anterior pituitary secretion of LH and FSH. Taking large doses of testosterone-like steroids also suppresses the secretion of GnRH and the pituitary gonadotropic hormones, resulting in sterility.

99. Cortisone is administered to a 30-year-old woman for the treatment of an autoimmune disease. Which of the following is most likely to occur? A) Increased ACTH secretion B) Increased cortisol secretion C) Increased insulin secretion D) Increased muscle mass E) Hypoglycemia between meals

99. C) Steroids with potent glucocorticoid activity tend to increase plasma glucose concentration. As a result, insulin secretion is stimulated. Increased glucocorticoid activity also diminishes muscle protein. Because of feedback, cortisone administration leads to a decrease in adrenocorticotropic hormone secretion and, therefore, a decrease in plasma cortisol concentration.

31. In the above figure, which lines most likely reflect the responses in a patient with nephrogenic diabetes insipidus? A) A and C B) A and D C) B and C D) B and D

B) In patients with nephrogenic diabetes insipidus, the kidneys do not respond appropriately to ADH, and the ability to form concentrated urine is impaired. In contrast, there is a normal ADH secretory response to changes in plasma osmolality

Questions 29 and 30 Match each of the patients described in Questions 29 and 30 with the correct set of plasma values listed in the table below. Normal values are as follows: plasma aldosterone concentration, 10 ng/dl; plasma cortisol concentration, 10 mg/dl; and plasma potassium concentration, 4.5 mEq/L. Aldosterone Concentration Cortisol Concentration Potassium Concentration A) 10.0 2.0 4.5 B) 2.0 2.0 6.0 C) 40.0 30.0 2.0 D) 40.0 10.0 4.5 E) 40.0 10.0 2.0

Questions 29 and 30 look at the table - couldn't paste here