HBY 531 MEDICAL PHYSIOLOGY

Lecture Exam 3

2001

Section 1: Answer the following using:

A = increase

B = not change

C = decrease

1. The diameter of the ileocolonic sphincter will _________ as secretin plasma levels are elevated.(B)

2. The diameter of the sphincter of Oddi will _________ in response to elevated CCK plasma levels.(A)

3. During the gastric phase of acid secretion in the stomach the lumenal Na⁺ will _________.(C)

4. Chief cell secretion of pepsinogen will __________ as plasma levels of secretin are elevated.(A)

5. Following a 20% blood loss in an otherwise healthy 30 year-old individual, urinary calcium excretion will __________.(C)

6. Following a sudden increase in dietary phosphate, urinary phosphate excretion will __________.(A)

7. In the time period preceding any compensatory response, total plasma calcium will __________ following a sudden infusion of citrate (an anion).(B)

8. Compared to normal, calcium excretion will __________ following a treatment involving the diuretic furosemide.(A)

9. During the last trimester of pregnancy, 1a-hydroxylase activity within proximal tubule cells will __________.(A)

10. Following stimulation of PTH receptors on osteoblasts, the rate of bone resorption will __________.(A)

11. In the presence of a carbonic anhydrase inhibitor, the rate of bone resorption will __________.(C)

12. Following a disruption of the tight junctions forming the blood-testis barrier within seminiferous tubules, the glucose concentration in the interstitial fluids of adluminal compartments will __________.(A)

13. The number of GnRH receptors on pituitary gonadotropes will __________ following a prolonged (i.e., 24 hours) exposure to GnRH. (C)

14. FSH release from gonadotropes will __________ following exposure to activin. (A)

15. Blood flow through helicine arteries of the penis will __________ following stimulation of sympathetic nerves to these arterioles. (C)

16. As estrogen levels increase during the follicular phase of the ovary, the viscosity of cervical mucus will __________. (C)

17. Body temperature will __________ under the influence of progesterone. (A)

18. Androgen production within granulosa cells of the ovary will __________ following stimulation of LH receptors on their surface. (B)

19. Aromatase activity within granulosa cells of the ovary will__________ following stimulation of FSH receptors on their surface. (A)

20. Prolactin inhibiting hormone release will __________ as a result of a baby suckling a breast. (C)

21. Following menopause, gonadotropin levels will__________. (A)

Section 2: Answer the following using:

A = higher

B = the same

C = lower

The chest X-ray of a 60 year old female patient demonstrates a large (6 cm) lesion of the right upper lobe with mediastinal adenopathy. You suspect that she is suffering from an ACTH secreting carcinoma and from the effects of hypercortisolism.

(use this information for questions 22-24)

22. When compared to a normal person, her 4PM ACTH level would be __________. (A)

23. Her blood ACTH levels would be __________ after a high dose dexamethasone (a potent glucocorticoid) suppression test.(B)

24. When compared to a normal person, her 8 AM cortisol level would be __________. (A)

A female patient with a normal chest X-ray suffers from the effects of hypercortisolism. The presumptive diagnosis is that there is a dysfunction in her hypothalamic-pituitary axis (Cushing’s Disease).

(use this information for questions 25-27)

25. When compared to a normal person, her 4PM ACTH level would be _________.(A)

26. Her blood ACTH level would be _________ after a low dose dexamethasone suppression test.(B)

27. Her blood ACTH level would be _________ after a high dose dexamethasone suppression test.(C)

Metyrapone is a drug used to decrease cortisol secretion as it blocks the 11-beta hydroxylase step necessary for the synthesis of both cortisol and aldosterone.

(use this information for questions 28-29)

28. The levels of in 11-Deoxycortisol (the precursor of cortisol) in a normal person will be _________ after taking Metyrapone.(A)

29. The late afternoon blood ACTH level in a normal person will be _________ after taking Metyrapone.(A)

Section 3: For each of the following, choose the single best response.

30. Smooth muscle cells in the muscularis externa of the duodenum will:

a. contract in the presence of VIP.

b. contract in the presence of Substance P.

c. contract in the presence of extracellular ATP.

d. both b and c are correct.

31. Secretin:

a. stimulates the secretions of pancreatic acinar cells.

b. causes smooth muscle cells in the fundic stomach to contract.

c. causes smooth muscle cells in the colon to contract.

d. causes smooth muscle cells of the gallbladder to contract.

32. Receptive relaxation:

a. is an example of a short reflex.

b. occurs in the small intestine.

c. will persist even if the vagus nerve is cut.

d. none of the above is true.

33. Which of the following is a feature of the gastroileal reflex?

a. relaxation of the muscularis externa of the ileum

b. It occurs only during fasting only.

c. relaxation of the ileocolonic sphincter by gastrin or VIP

d. It is triggered by distension of the colon.

34. A key manifestation of the enterogastric inhibitory reflex is:

a. that it is triggered by distension of the colon.

b. that it is mediated by Auerbach’s plexuses only making it a short reflex.

c. relaxation of the pyloric sphincter by gastrin.

d. it is triggered by acid and hypertonic solutions entering the duodenum.

35. Doubling the activity of the Na⁺/H⁺ exchanger, found on the lumenal surface salivary duct cells, would result in:

a. lower levels of Na⁺ in saliva secreted at maximal flow rates.

b. a more alkaline saliva.

c. a more hypertonic saliva.

d. an increase in the concentration of Cl^- in the saliva.

36. What is the fate of a chylomicron remnant?

a. transcytosis into tissues from capillaries

b. It is further acted on by endothelial lipoprotein lipase (LPL) to become an IDL.

c. It is sequestered via endocytosis into hepatocytes.

d. It is converted into VLDL by endothelial lipase.

37. With regard to crypt cell secretion:

a. if the apical Cl^- channels are open, the Cl^- equilibrium potential is –40 mV, and the resting potential is –40 mV; then the flux of Cl^- between cell and lumen will be outward.

b. if the apical Cl^- channels are open, the Cl^- equilibrium potential is –40 mV, and the resting potential is –60 mV; then the flux of Cl^- between cell and lumen will be inward.

c. if all the apical Cl^- channels are closed, the Cl^- equilibrium potential is –40 mV, and the resting potential is –60 mV; then the net flux of Cl^- between cell and lumen will be inward.

d. none of the above are true.

38. Inhibition of the enzyme enterokinase would result in:

a. diarrhea.

b. no change in carboxypeptidase A activity.

c. an increase in phospholipase A activity.

d. the inhibition of pancreatic amylase.

Inorganic content has been determined from fluid samples taken from your patient in the duodenum, jejunum, ileum and from fecal material and compared with normal. The data (mM) are shown in the following Table.

(use this information for questions 39-40)

Normal

Na⁺ K⁺ Cl^- HCO₃^-

Duodenum 60 15 60 15

Jejunum 140 6 100 30

Ileum 140 8 60 70

Feces 40 90 15 30

Patient

Na⁺ K⁺ Cl^- HCO₃^-

Duodenum 95 8 90 15

Jejunum 140 6 100 30

Ileum 140 8 90 40

Feces 40 90 90 10

39. The elevated Na⁺ in the duodenum for the patient most likely results from:

a. too much mucus being secreted by the columnar cells lining the stomach mucosa.

b. lowered secretion of H⁺ by parietal cells.

c. increased salivary secretions.

d. increased activity of the H⁺/K⁺ pump.

40. The elevated Cl^- concentration in the ileum and fecal sample of the patient indicate that:

a. Na⁺ absorption/resorption is dysfunctional.

b. the apical Cl^-/HCO₃^- exchanger on the columnar absorptive cells of the ileum and colon is dysfunctional.

c. the basolateral Na⁺/HCO₃^- cotransporter on the columnar absorptive cells is dysfunctional.

d. either b or c.

41. Bile salts:

a. are recycled at most once a day.

b. are resorbed only by active transport.

c. are synthesized by hepatocytes only.

d. are lost in the feces at a rate of approximately 30% per day.

42. A deficiency of ApoC-2 will result in:

a. a decrease of VLDL plasma levels during the absorptive state.

b. an increase in chylomicrons remnants during the absorptive state.

c. an elevated chylomicron concentration during the absorptive state.

d. an elevated LDL concentration during the absorptive state.

An individual has ingested 0.7L of fluid with a pH of 6.9 at the 1hour mark. You are monitoring stomach pH, stomach volume and small intestine volume.

(use this information for questions 43-46)

43. The reduction in small intestine volume between hours 5 and 6 is most likely due to:

a. reduced bile secretion

b. the myenteric reflex.

c. defecation.

d. none of the above.

44. The number of moles of H⁺ produced at the 2hour mark is:

a. 2 x 10^-6 moles

b. 2 x 10^-5 moles

c. 1 x 10^-4 moles

d. 2.5 x 10^-7 moles

45. The volume of stomach secretions is:

a. 0.1 L

b. 1.3 L

c. 2.0 L

d. 0.5 L

46. With regard to the small intestine volume vs. time relationship, which reflex is missing?

a. gastro-gastric

b. enterogastric inhibitory

c. gastroileal

d. myenteric

47. During a complicated delivery, the mother experienced excessive blood loss and suffered from a significantly lowered blood pressure for at least one hour. Even though she has not been nursing her child, she reports that three months post partum she had not begun her previously normal menstrual cycles and that she feels fatigued and cold all the time. Which of the following is likely to be noted on laboratory examination of this patient?

a. A normal rise in the levels of ACTH after a standard Metyrapone test which markedly decreases the production of cortisol.

b. A normal circadian rhythm for ACTH and cortisol.

c. An increase in circulating levels of TSH.

d. A decrease in circulating levels of TSH after a TRH stimulation test.

e. A high level of blood cortisol at 8 AM.

48. Which of the following is true regarding thyroid hormone regulation?

a. MIT and DIT (mono and diiodotyrosines) released by the thyroid gland are activated by enzymes in the liver.

b. T₄ binds to TSH receptors on the plasma membranes of liver cells to directly induce the synthesis of malic enzyme.

c. T₄ is converted to rT₄ (reverse T₄) by brain cells to provide for normal functioning of these cells, particularly during starvation.

d. In hypothyroidism, frequently an auto antibody mimics the action of TSH on the thyroid gland to increase the synthesis, storage and release of T₄.

e. During starvation brain cells increase the production of T₃ from T₄ by an increase in the activity of a specific deiodinase.

49. In a patient with hyperthyroidism, which of the following would be expected?

a. An increased systolic pressure with a relatively low diastolic pressure.

b. A warm wet skin with a dislike for warm temperatures.

c. An increase in the basal metabolic rate.

d. An increase in circulating T₄ levels.

e. all of the above

50. A patient suffers from Addison’s Disease which is caused by the auto immune mediated destruction of the adrenal cortex. In this patient you would expect:

a. a lower level of serum Na⁺ and a higher level of serum K⁺ than normal.

b. very low levels of epinephrine in the blood.

c. a lower blood level of ACTH and TSH.

d. a decrease in the pigmentation of the mucous membranes and skin.

e. hypotension and hyperglycemia.

51. A patient is treated for three months with pharmacologic doses of dexamethasone. In this patient you would expect:

a. blood ACTH levels to be high in the 8 AM blood sample.

b. blood cortisol levels to be high throughout the 24 hour period.

c. aldosterone levels to be higher than normal.

d. blood TSH levels to be high throughout the 24 hour period.

e. the patient to demonstrate glucose intolerance to an oral glucose load.

52. All hormones act as allosteric effectors. As such they are involved in regulating processes related to:

a. production, use and storage of metabolic energy.

b. reproduction of the species.

c. maintenance of the internal milieu (homeostasis).

d. differentiation, growth and development of the organism.

e. All of the above.

53. In a patient with a deficiency of the 21-hydroxylase enzyme during embryogenesis or early childhood you would expect:

(Reminder: 21-hydroxylase converts progesterone to 11-deoxycorticosterone (DOC) and 17-OH-progesterone to 11-deoxycortisol, controlling the production of cortisol and aldosterone.)

a. higher than normal levels of Na⁺ and lower than normal levels of K⁺ in the blood.

b. hyperplasia of the zona fasciculata and zona reticularis of the adrenal cortex.

c. abnormal genital development in the male fetus during embryogenesis.

d. higher than normal levels of cortisol at 8 AM.

e. hypotension often leading to syncope (fainting spells).

54. Many hormones bind to blood proteins. Which of the following is a purpose and/or consequence of this binding?

a. Binding of the hormone to protein makes it more readily accessible to the interior of the target cell as there are specific plasma membrane transporters for the hormone protein complex.

b. Binding of the hormone to protein makes it more easily filtered, and then reabsorbed in the kidney, limiting its excretion in the urine.

c. Binding of the hormone to protein makes unnecessary to measure “free hormone” in the blood.

d. Binding of hormone to protein in the blood, in some cases, provides a large reservoir of hormone and as such can serve to buffer acute changes in total hormone levels.

e. During pregnancy there is an increase in thyroid hormone binding globulin, which decreases the total level of circulating T₄.

55. The following is NOT an effect of growth hormone?

a. Fat cells are rendered more sensitive to epinephrine.

b. During starvation it increases muscle’s uptake of glucose for a given concentration of insulin.

c. It increases the production of somatomedins (IGF1 and IGF2).

d. It facilitates the growth of long bones in children.

e. After ingestion of protein, it promotes the synthesis of muscle.

56. Which of the following stimulates release of a hormone from the anterior pituitary?

a. hyperosmolality

b. suckling during lactation

c. IGF1 and IGF2

d. elevated T₄ levels

e. somatostatin

57. Sequencing of a patient’s insulin gene revealed a substitution of both lys-62 and arg-63 into alanine. Which of the following statements would BEST describe the consequences of these mutations?

a. The circulating connecting C-peptide to insulin ratio would remain high after a meal.

b. Exocytosis of granules from the pancreatic b-cells in response to glucose would be decreased.

c. The patient would require periodic insulin injections to properly regulate blood glucose levels.

d. The glucose tolerance curve would be normal to slightly elevated, since there is only a small change in the biological activity of the insulin.

58. In humans, the adaptation to fasting requires:

a. the proper secretion of insulin in response to increased circulating amino acids.

b. the intracellular accumulation of cyclic AMP in liver cells.

c. the inhibition of hepatic ketogenesis to conserve body fuels.

d. the inhibition of adenylyl cyclase in adipose tissues.

59. Which of the following enzymes is inhibited by cyclic AMP-dependent phosphorylation?

a. liver pyruvate kinase

b. adipocyte lipoprotein lipase

c. muscle phosphorylase kinase

d. pancreatic b-cell glucokinase

60. The effects of insulin on skeletal muscle glucose utilization:

a. start with increased localization of GLUT-4 to the plasma membrane.

b. result from an increase in the affinity of GLUT-4 for glucose.

c. are caused by the phosphorylation of GLUT-4 and an increase in its V_max without affecting the affinity for glucose.

d. result from an increase in the rate of glucose phosphorylation catalyzed by glucokinase.

61. A 2-year old child in a hypoglycemic (low blood glucose) coma is immediately given glucagon intravenously. After 10 minutes, blood glucose levels remained low. A likely explanation for these findings is:

a. the patient has no glucose-6-phosphatase activity as a result of heredity.

b. the patient has inherited a constitutively active mutant of adenylyl cyclase.

c. the patient has eaten only protein for several days before the coma.

d. the patient has inherited a defective insulin receptor gene.

62. Which of the following is NOT stimulated by insulin?

a. glycogen synthesis

b. triglyceride synthesis

c. pyruvate formation from glucose

d. chylomicron synthesis

63. Stimulation of glucagon release from the pancreas in response to an increase in circulating amino acids:

a. is concurrent with insulin release, only when blood glucose is high.

b. is increased by insulin secretion from the b-cells.

c. decreases the level of urea in urine, because of decreased deamination by the liver.

d. allows for gluconeogenesis even during absorptive phase.

64. The product of the glucagon gene is:

a. glicentin + GLP-1 + GLP-2 in intestinal L-cells.

b. glucagon + GRPP in pancreatic a cells and only GRPP in intestinal L cells.

c. preproglucagon that is processed in circulation to give biologically active glucagon.

d. stimulated by the secretion of insulin from the b-islet cells.

65. While the IRS is the Internal Revenue Service, IRS-1 is:

a. a tyrosine kinase.

b. a serine/threonine kinase.

c. a protein with multiple tyrosine phosphorylation sites.

d. the insulin receptor in its phosphorylated form.

66. The rate‑limiting step that mediates glucose‑control of insulin release is:

a. the ATP‑sensitive K⁺ channel.

b. b-cell glucokinase.

c. the high K_m b‑cell glucose transporter GLUT-4 .

d. the Ca²⁺-mediated fusion of the granules with the plasma membrane.

67. An untreated type I diabetic (IDDM):

a. has increased rates of chylomicron clearance from the blood.

b. is likely to test positive for an Islet-cell Antibody (ICA) assay.

c. has very low levels of fatty acids in the blood because of the absence of insulin.

d. can be treated by daily administration of antibodies to human glucagon.

68. A type II diabetic (NIDDM) has decreased rates of blood glucose clearance because:

a. there is decreased expression of the IRS-1 protein associated with obesity.

b. the expression of insulin processing proteases (PC2 and PC3) decreases with age and obesity.

c. there is a down-regulation of insulin receptors associated with increased body weight.

d. hepatic levels of fructose-2,6-bisphosphate increase with age and obesity.

69. Which of the following conditions could account for a patient having elevated PTH while at the same time being mildly hypocalcemic?

a. a PTH secreting tumor.

b. a PTHrp (PTH related peptide) secreting tumor

c. a vitamin D (calcitriol) receptor defect

d. vitamin D resistant osteomalacia

e. both a and b

70. The filtered load of calcium within the kidney would be expected to increase in which of the following conditions?

a. hypoparathyroidism

b. pseudohypoparathyroidism

c. type II vitamin D dependent osteomalacia

d. vitamin D resistant osteomalacia

e. both c and d

71. The filtered load of phosphate within the kidney would be expected to increase in which of the following conditions?

a. hypoparathyroidism

b. type I vitamin D dependent osteomalacia

c. primary hyperparathyroidism

d. hypercalcemia of malignancy (elevated PTHrp)

e. none of the above

72. Following the sudden development of primary hyperparathyroidism, which of the following would be expected?

a. The concentration of calbindins within columnar absorptive cells would increase.

b. Plasma calcium levels would fall.

c. Phosphate reabsorption within the proximal tubule would increase.

d. The rate of bone resorption would decrease.

e. none of the above

73. Within the kidney, most calcium reabsorption takes place:

a. the proximal tubule.

b. the loop of Henle.

c. the distal tubule.

d. collecting ducts.

e. the different portions of the nephron equally.

74. Among the different types of osteomalacia, which of the following involve elevated plasma calcitriol?

a. osteomalacia due to a sunlight/dietary deficiency

b. type I dependent osteomalacia

c. type II dependent osteomalacia

d. vitamin D resistant osteomalacia

e. both c and d

75. Following a sudden decrease in dietary phosphate, which of the following would be expected?

a. Chief cell secretion of PTH would increase.

b. Proximal tubule 1a-hydroxylase activity would increase.

c. The filtered load of phosphate in the kidney would increase.

d. Calcium reabsorption within the distal tubule would increase.

e. both a and d

76. Which of the following conditions is most consistent with lab values which indicate hypercalcemia, hyperphosphatemia, and low PTH?

a. hypoparathyroidism

b. hypercalcemia of malignancy (elevated PTHrp)

c. vitamin D dependent osteomalacia

d. vitamin D toxicity

e. none of the above

77. Following an exposure of Sertoli cells to FSH, which of the following will increase?

a. the transcription rate of the b-subunit of FSH within gonadotropes

b. the production rate of estradiol within Sertoli cells

c. the rate of conversion of cholesterol to pregnenolone within Leydig cells

d. the rate of destruction of spermatocytes

e. both a and b

78. Following an exposure of Leydig cells to LH, which of the following will increase?

a. the transcription rate of the b-subunit of FSH within gonadotropes

b. the transcription rate of the b-subunit of LH within gonadotropes

c. the rate of conversion of cholesterol to pregnenolone within Leydig cells

d. the rate of destruction of spermatocytes

e. both a and b

79. Within the fetal gonad, the primitive cell line that gives rise to theca cells in the ovary produces which cell type in the male?

a. spermatogonia

b. primary spermatocytes

c. Sertoli cells

d. Leydig cells

e. fibroblasts

80. An individual who is 46, XY but has a dysfunctional X chromosome will most likely have:

a. testes, male internal and external genitalia.

b. testes, female internal and external genitalia

c. testes, no internal genitalia, but female external genitalia

d. testes, male internal genitalia, but female external genitalia

e. testes, female internal genitalia, but male external genitalia

81. There have been rare situations in which a 46, XX individual develops testes, male internal and external genitalia. The most likely explanation for this disparity between genetic sex, gonadal sex, and phenotypic sex involves:

a. the transfer of the SRY gene from a paternal Y to the paternal X chromosome that was contributed at fertilization.

b. the fact that this individual lacks androgen receptors.

c. the fact that this individual lacks 5a-reductase activity.

d. the lack of Mullerian ducts during embryogenesis.

e. overactive aromatase activity producing abnormally high estrogen levels in this individual.

82. Cell bodies of primary afferent neurons that convey sensory input from the glans penis to the central nervous system during the sexual response reside in:

a. cranial nerve nuclei.

b. the splanchnic plexus.

c. autonomic ganglia located within the penis.

d. dorsal root ganglia associated with the lumbar spinal cord.

e. dorsal root ganglia associated with the sacral spinal cord.

83. Semen analysis taken 72 hours after sexual abstinence in a male suspected of infertility revealed an ejaculate volume within the normal range, but a low sperm count (oligospermia). Blood tests revealed that testosterone, LH and FSH levels were all low. Which of the following conditions could account for these findings?

a. hypogonadism associated with a defect in testosterone synthesis

b. hypogonadism associated with varicocele

c. Klinefelter’s syndrome

d. a prolactin-secreting tumor of the pituitary

e. both b and d

84. In a different male suspected of infertility, semen analysis taken 72 hours after sexual abstinence revealed a low sperm count and a relatively low ejaculate volume (only 1.25 mL). Blood tests revealed normal testosterone, LH and FSH levels. Further analysis revealed an abnormally low fructose content within the semen sample. Based on this information, the most likely cause of this infertility is:

a. a partial blockage of the ejaculatory ducts

b. hypogonadism associated with cryptorchidism

c. hypogonadism associated with a prolactin-secreting tumor

d. hypergonadotropic hypogonadism

e. both a and b

85. The LH surge which precedes ovulation:

a. results from a sudden drop in estradiol production by the dominant follicle.

b. produces a sharp increase in granulosa cell numbers within the dominant follicle.

c. occurs without any increase in GnRH.

d. results from positive feedback involving estradiol.

e. both c and d

86. Within the uterine cycle, menses is associated with:

a. the luteal phase of the ovarian cycle.

b. high levels of both estrogen and progesterone.

c. low levels of both estrogen and progesterone.

d. elevated levels of human chorionic gonadotropin (hCG).

e. both a and b

87. Which of the following hormones released during pregnancy reaches its maximal value during the first trimester?

a. hCG

b. progesterone

c. estradiol

d. chorionic somatomammotropin

e. prolactin

88. Which of the following conditions could account for amenorrhea in a 32 year old patient that has normal prolactin but elevated LH and FSH?

a. primary hypothyroidism

b. an outflow tract defect

c. premature ovarian failure

d. hypothalamic amenorrhea attributable to anorexia

e. both a and d

89. A 19 year old patient seeks medical attention because she has never had a menstrual cycle but does exhibit normal secondary sex characteristics and does experience monthly bloating and breast tenderness. A hCG test (pregnancy) was negative and she has normal lab values for prolactin, LH and FSH. At this point, the most reasonable test to perform to assess the cause of her amenorrhea would be:

a. a MRI of the pituitary to look for a tumor.

b. a karyotype.

c. a GnRH stimulation test.

d. a progesterone withdrawal test.

e. a glucose tolerance test.

90. All of the following will relax uterine smooth muscle EXCEPT:

a. prostaglandins

b. relaxin

c. progesterone

d. oxytocin

e. both a and d