HBY 531 Organ Systems
Final Examination
1997
Section 1: Answer the following using:
A = increases
B = no change, or remains unchanged
C = decreases
1. After removal of a large portion of the jejunal region of the intestine, bile acid uptake __________.
2. Measured 2 hours after a high fat meal, the plasma chylomicron concentration __________ compared to fasting levels.
3. The diameter of the Sphincter of Oddi __________ in response to gastrin.
4. If the intracellular potassium concentration is increased from 125 mM to 145 mM within the columnar absorptive cell causing the resting potential to becoming more negative, the rate at which glucose is absorbed __________.
5. Decreasing the Na+ equilibrium potential for columnar absorptive cells (i.e., intracellular Na+ increases or lumenal Na+ decreases) results in __________ in the rate of glucose absorption.
6. During the cephalic phase of acid secretion of the stomach, the lumenal Na+ concentration __________.
7. Infusion of calcitriol into the nutrient artery of the humerus will result in __________ in plasma calcium measured within the venous drainage of that bone 20 minutes later.
8. Collagen type I synthesis __________ in response to calcitonin.
9. Chronic (i.e., long term) exposure of calcitriol to chief cells results in __________ in PTH mRNA production.
10. Prolactin input to proximal tubule cells of the kidney results in __________ in the activity of the enzyme 1-hydroxylase.
11. Between the ages of 55-65 years, net bone loss __________ in hypogonadal men compared to men with normal gonadal function.
12. Application of nitric oxide to helicine arteries of the penis results in __________ in their luminal diameter.
13. Application of a muscarinic agonist to the bulbouretheral gland results in ___________ in secretion.
14. Application of a muscarinic agonist to the smooth muscle of the vas deferens will result in _________ in motility.
15. Thymidine incorporation into granulosa cells from a primary follicle __________ upon exposure to FSH.
16. FSH results in __________ in progesterone production by granulosa cells from a graffian or antral follicle.
17. Inhibin production by granulosa cells __________ upon exposure to FSH.
18. The pulse frequency and amplitude of GnRH secretion __________ upon exposure to estrogens.
19. The number of LH receptors on granulosa cells __________ upon exposure to estrogens.
20. Human chorionic somatotropin results in __________ in glucose utilization by muscle tissues in the mother.
21. Human chorionic somatotropin results in __________ in fetal growth.
Section 2: For each of the following, choose the single best response.
Use the figure above to answer questions 22-26. Here, two individuals were asked to ingest 1L of solution which had a pH of 7.0. Stomach pH was monitored in both individuals over a 5 hour period at 30 minute intervals. Three measurements were made before ingesting the 1L volume. The resting volume of the stomach before the intake of fluid was 0.1 L. The stomach volume for the two individuals has also been plotted. The volume data for the two were identical. At the 2 hour mark a sample of stomach contents was taken and amylase content determined. For the first individual (circles) the amylase concentration was 1mg/ml and it was 1.2 mg/ml for the second individual (diamonds). The concentration of amylase in saliva is ~40 mg/ml.
22. For the circle date, the total secretory volume attributable to stomach secretions is:
a. 1.3 L
b. 0.9 L
c. 0.3 L
d. 2.1 L
e. none of the above
23. For either individual:
a. receptive relaxation had a duration of approximately 90 minutes.
b. there is not indication of receptive relaxation.
c. stomach emptying is driven soley by local reflexes.
d. the myenteric reflex drives stomach emptying.
24. The plasma level of gastrin in the individual represented by the diamonds was elevated before ingesting the 1 L of fluid. During and after the intake the gastrin levels were 2 times that found in the individual represented by the circles. Resting secretin levels were found be in the normal range for both individuals.
a. The resting stomach pH (diamonds) is unaffected by gastrin.
b. Parietal cells are more sensitive to secretin than gastrin.
c. The individual who secretes more acid might be suffering from a proliferation of gastrin secreting cells.
d. The increased acidity could be the result of acidic salivary secretions.
e. none of the above are true.
25. For the diamond data at the 2.5 hour time point the total number of moles of H+ secreted in response to the ingesting of the 1 L of fluid was:
a. 10-3 moles
b. 0.5 x 10-3 moles
c. 10-5 moles
d. 0.5 x 10-5 moles
e. none of the above
26. Consider the circle data. If no acid secretion took place after ingesting the 1 L of fluid the stomach pH would be in the range of :
a. 5
b. 3
c. 6
d. 4
27. For a crypt cell in the small intestine, the intracellular Cl- concentration is 40 mM and the lumenal Cl- is 120 mM. The resting potential of the cell is -60 mV. ECl=50log(Ci/Co) or 25 ln (Ci/Co).
a. The equilibrium potential for Cl- is -60 mV.
b. The net flux of Cl- is inward.
c. The net flux of Cl- is 0.
d. The net flux of Cl- is outward
e. None of the above is true.
28. Input to Auerbachs plexus can arise from:
a. sympathetic postganglionic fibers.
b. sensory fibers from receptors in the gut wall.
c. parasympathetic postganglionic fibers.
d. parasympathetic preganglionic fibers.
e. a, b and d are correct
29. Local application of Ca2+ channel blockers to the duodenum
a. would result in increased segmentation rates within the duodenum.
b. would result in a slowing of the movement of material through the small intestine.
c. would abolish slow waves.
d. could inhibit or abolish action potentials generated by smooth muscle cells in duodenum.
e. b and d are true
30. Pancreatic secretion:
a. during the cephalic phase is not influenced by secretin.
b. contains bicarbonate ions which can be attributed to the secretion by acinar and duct cells.
c. from acinar cells during the intestinal phase is most influenced by CCK.
d. from duct cells during the intestinal phase is most influenced by CCK.
e. b and c are true
31. With regard to bile:
a. 95-99% of secreted bile acids are recycled.
b. the liver hepatocytes decrease their secretion of bile in response to CCK.
c. only primary bile acids are recycled.
d. the heptocyte is the only site where bile acids are modified.
32. The hormone CCK:
a. causes the gallbladder to relax.
b. causes the sphincter of Oddi to relax.
c. has no effect on pancreatic secretions.
d. is released into the blood by the presence of H+ in the intestinal lumen.
e. none of the above is true
33. A patient presents complaining of periodic and persistent diarrhea. It is not due to dairy products. Tests in which the patient was asked to drink 1.5 L isosmotic NaCl solution did not cause an episode of diarrhea.
a. The diarrhea could result from a lack of amino acid transports.
b. The diarrhea could result from decreased pancreatic secretions.
c. The diarrhea could be the result of a lack of Cl:HCO3 exchangers on the apicial surface of the columnar absorptive cells.
d. The diarrhea could be the result of a lack of Na:H exchanges on the apicial surface of the columnar absorptive cells.
34. The smooth muscle cells of the circular layer of the muscularis externa of the large intestine:
a. contract in response to VIP.
b. contract in response to NO.
c. will remain tonicly contracted if Auerbach’s plexus is absent.
d. are unaffected by any of the known gastrointestinal reflexes.
35. Pick the least correct answer:
a. Chylomicrons contain apoprotein B.
b. The only apoprotein found in LDLs is apoprotein B.
c. HDLs contain both A and C apoproteins.
d. VLDLs contain some apoprotein E.
36. An individual sweats at a rate of 600 ml/hour for three hours and is working in the shade. The ambient temperature is 70 F. There is no breeze and the individual is wearing a shirt and pants. The metabolic rate of the individual during this three hour period is 600 kcal/hour. Assume the metabolic rate is proportional to/equivalent to total heat lost per hour in kcal/hour. Which statement is true?
a. The amount of heat lost due to heat conduction and radiative loss is 350 kcal/hour.
b. The amount of heat lost due to heat conduction and radiative loss is 476 kcal/hour.
c. Heat loss (heat conduction and radiative heat loss) due to blood flow is responsible for eliminating approximately 83% of the metabolic heat in this case.
d. The amount of heat lost due to water evaporation is less than 324 kcal/hour.
37. With regard to the skin, which statement is true?
a. The stratum basale contains stem cells for keratinocytes.
b. The permeability characteristics of the skin are embodied for the most part in the stratum basale.
c. The turn over time for a keratinocytes is approximately 14-28 days.
d. Melanosomes contain the enzyme tryosinase.
e. a, c, and d are true
38. Within the endocrine system specificity of communication is determined by:
a. The chemical nature (peptide, protein, amino acid, steroid or ion) of the hormone.
b. The distance between the hormone producing cell and its target cells.
c. The presence of specific receptors with high affinity for the hormone on its target cells.
d. Anatomic connections between the endocrine and target cells provide the additional linkage to assure specificity.
39. Which of the following decreases the rate (including number of pulses per unit time) of ACTH secretion by the corticotrophs of the anterior pituitary:
a. An increase in ADH (Vasopressin) in hypophyseal portal blood bathing the anterior pituitary.
b. Stress (both physical and emotional).
c. Destruction of the appropriate cell neurons in the paraventricular nuclei of the hypothalamus.
d. Destruction of the adrenal cortex by metastatic cancer or tuberculosis.
40. Glucocorticoids such as cortisol have the following effect(s):
a. Stimulate the expression of the gene for CRH in select hypothalamic neurons.
b. Stimulate the expression of the gene for POMC. (proopiomelanocorticotrophs) in specific cells of the anterior pituitary.
c. Increase the secretion rate of CRH by select hypothalamic neurons.
d. Have a direct negative feedback effect on the corticotrophs of the anterior pituitary to inhibit ACTH secretion.
41. Thyroid hormones such as T3:
a. Stimulate the sensitivity of the thyrotrophs of the anterior pituitary to the action of TRH.
b. Stimulate the expression of the genes for the a and b subunits of TSH in the thyrotrophs.
c. Decrease the secretion of TSH by the thyrotrophs of the anterior pituitary.
d. Inhibit the expression of the gene for GH in the somatotroph.
42. Which of the following is not an effect of human Growth Hormone:
a. Decreases the production of somatomedins (IGF-1) by the liver.
b. Stimulates triglyceride lipolysis in fat cells.
c. Production of insulin resistance.
d. with prolactin and insulin, it stimulates milk synthesis by the lactating mammary gland.
43. Metyrapone is a drug used to control cortisol secretion in Cushing's syndrome. It blocks 11-beta-hydroxylase. One of the side effects is hirsutism in women. This occurs because:
a. The drop in cortisol levels after drug treatment stimulates ACTH release, which creates more DHEA.
b. Lowered levels of cortisol secreted after drug therapy cause an upregulation of cortisol receptors increasing activity of other pathways in the zona reticularis.
c. Metyrapone treatment causes increased quantities of aldosterone to be secreted by the zona glomerulosa of the adrenal gland, which has significant androgen activity.
d. Lowered levels of cortisol secreted after drug therapy causes a decrease in CRH production in the hypothalamus causing a decrease in ACTH secretion by the the anterior pituitary causing an increase in androgens by the adrenal gland.
44. In which of the following would ADH secretion be decreased?
a. A continuous intravenous infusion of hypertonic NaCl solution.
b. A man who has lost 4 units of blood (2 liters) because his popliteal artery was severed in a knife fight.
c. A woman with a psychoses who drank 12 liters of water in 18 hours.
d. A man who had a severe bleeding duodenal ulcer with an acute loss of liters of blood.
45. In which of the following would ADH secretion by the posterior pituitary be increased?
a. A man who has just had one liter of his favorite beer (Bass Ale).
b. A man who has just had acute significant blood loss from a duodenal ulcer.
c A woman who has had a continuous, albeit slow intravenous infusion over 6 hours, of 1.5 liters of hypotonic saline.
d. A woman, a few days after a severe auto accident in which she had brain damage resulting in the severing of the posterior pituitary stalk.
46. Which of the following is not a general characteristic of peptide hormones?
a. Peptide hormones are transported in the blood largely free in solution.
b. Peptide hormones are usually converted within the target cell from a pro hormone to the active hormone.
c. Peptide hormones utilize cell membrane receptors and intracellular second messengers.
d. Peptide hormones are usually first synthesized as a larger precursor protein.
47. Hormones are involved in regulating processes related to:
a. production, use and storage of metabolic energy.
b. reproductive functions.
c. differentiation, growth and development.
d. salt and water balance including maintenance of blood pressure and vascular volume.
e. all of the above.
48. Which of the following is not a significant secretory product of the trophic cells of the anterior pituitary:
a. Growth hormone (GH)
b. Prolactin
c. Somatomedins
d. ACTH
e. TSH
49. In the thyroid gland, the iodide trap:
a. is responsible for the conversion of thyroglobulin into thyroid hormone.
b. removes iodide form MIT and DIT for resynthesis of thyroid hormone.
c. is located on the basal surface of the cell and is responsible for transporting iodide from the extracellular space into the thyroid follicle cell.
d. is directly responsible for transporting iodide from the intracellular space into the colloid space for the coupling that takes place in the colloid space.
50. Autoregulation when applied to the thyroid gland refers to:
a. an increase in iodide oral intake increases the activity of the iodide trap.
b. an increase in iodide oral intake causing a marked increase in the synthesis of thyroid hormone to effectively use the extra dietary iodide.
c. a large oral dose of iodides can be used to decrease the activity of an overactive thyroid (Graves disease).
d. a marked increase in both the size and vascularity of the thyroid gland with an increase in the oral intake of iodides.
51. In a patient, intolerance to cold, constipation, mental aberrations, reduced cardiac output and pleural and peritoneal fluid accumulations may be due to:
a. chronically increased blood levels of triiodothyronine (T3) and thyroxine (T4).
b. chronically decreased blood levels of T3 and T4.
c. the acute reduction in the oral intake of iodides leading within a few days to the signs and symptoms listed above.
d. a patient’s inappropriate and chronic oral ingestion of large quantities of thyroxine.
52. Adrenogenital Syndrome is the term given to a group of diseases in which there are congenital enzyme deficiencies in pathways of adrenocortical hormone syntheses. A deficiency of the 21-hydroxylase enzyme which converts progesterone to 11-deoxycorticosterone (DOC) and 17-OH-progesterone to 11-deoxycortisol limits the production of cortisol and aldosterone. In such a patient, during embryogenesis or during early childhood, you would expect to find:
a. a decrease in the secretion of ACTH by the anterior pituitary.
b. hyperplasia of the zona fasciculata and reticularis.
c. decreased masculinization of the female child.
d. increased levels of cortisol.
e. an increased production of aldosterone and a decreased production of DHEA.
53. In Addison's disease (destruction of the adrenal cortex) you would expect:
a. a decrease in the blood level of ACTH.
b. a decrease in the hypophyseal portal blood concentration of CRH.
c. An increase in blood cortisol levels in the very early morning samples.
d. Probable hyperpigmentation of the mucous membranes and skin of the afflicted patient.
54. In a patient suffering from the effects of slow destruction of the pituitary by a non-hormone producing tumor you would expect:
a. the patient to be able to regulate salt and water balance in a relatively normal manner.
b. the patient to be able to withstand the stress of major surgery in a relatively normal manner.
c. ACTH levels to be very high.
d. DHEA levels to be very high.
55. In a patient being treated with pharmacologic doses of Dexamethasone (a potent glucocorticoid) for active rheumatoid arthritis you would expect:
a. ACTH blood levels to be high.
b. cortisol blood levels to be high in the early morning.
c. that the patient might exhibit glucose intolerance as manifested by an abnormal glucose tolerance test.
d. that the patient would manifest resistance to infection by tuberculosis.
56. The hydrolysis of glycogen in liver cells increases:
a. when glycogen synthetase is dephosphorylated.
b when glucagon levels in the blood increase.
c. when glucose-6-phosphatase activity is increased.
d. when adenylyl cyclase activity is decreased.
57. Insulin is released from the b cell of the Islets of Langerhans:
a. in response to an increase in the number of glucose transporters (GLUT-4) at the plasma membrane.
b. as a disulfide-linked dimer of chains A and B, and an equimolar amount of
connecting C-peptide.
c. in response to an increase in blood glucose but not amino acids.
d. in response to the stimulatory effect of epinephrine.
58. The insulin gene is composed of 3 exons, 2 introns and:
a. is only present in the endocrine pancreas.
b. is transcribed into mRNA, that is translated at the microsomal membrane into proinsulin.
c. the sequences coding for chains B and A are in exons 2 and 3, respectively, as are parts of the connecting C-peptide.
d. its sequence, particularly intron size, is highly conserved in all mammals.
59. An untreated type I (IDDM) diabetic:
a. has increased rates of chylomicron clearance from the blood.
b. tests positive in 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 administration of antibodies to human glucagon.60.
60. Gluconeogenesis in hepatocytes is increased in a type II (NIDDM) diabetic because:
a. more insulin receptors are present at the plasma membrane.
b. there are higher levels of fructose-2,6-bisphosphate.
c. glucose-6-phosphatase and PEPCK mRNA are induced.
d. there is an reduction in the level of glucokinase mRNA.
61. Activation of adenylyl cyclase in muscle cells:
a. is the result of glucagon binding to its receptor.
b. results in the phosphorylation of glycogen phosphorylase and glycogen synthetase.
c. results in the release of the catalytic subunit of cAMP-dependent protein kinase.
d. all of the above
62. Chylomicrons from the small intestine:
a. enter portal circulation at a slower rate than glucose because they require apoprotein C2 before they can be metabolized by lipoprotein lipase.
b. and very low density lipoproteins (VLDL) are both triglyceride rich particles, but have different pathways of catabolism.
c. form remnant particles after hydrolysis by lipoprotein lipase in the capillary endothelium of adipose and muscle.
d. acquire apoprotein E from high density lipoproteins, which results in the activation of lipoprotein lipase.
63. Expression of the glucagon gene:
a. leads to the formation of two different mRNA’s in the a cell of the pancreatic islet and the intestinal L cell.
b. in the islet a cell is preproglucagon which is proteolytically cleaved to give glucagon, glucagon related polypeptide (GRPP) and a C-terminal peptide.
c. is suppressed by glucose and amino acids.
d. is stimulated by somatostatin secretion from islet D cells.
64. Which of the following is NOT a characteristic of liver cells:
a. b -oxidation of fatty acids into ketone bodies
b. gluconeogenesis from acetyl CoA
c. the formation of urea from carbon dioxide and ammonia
d. the secretion of very low density lipoproteins in the absorptive phase of
metabolism
65. Perfusion of glucagon into the portal system of a rat increases:
a. the level of fructose-2,6-bisphosphate in the liver.
b. GLUT-2 levels in the plasma membrane of the liver cell.
c. the activity of pyruvate kinase.
d. the activity of glycogen phosphorylase
66. An increase in blood glucose would increase:
a. the uptake of Ca2+ into the b cell of the pancreatic islets.
b. rates of insulin mRNA degradation.
c. the Km of glucose transporter-4 (GLUT-4) in the plasma membrane of adipose tissue cells.
d. the number of insulin receptors in muscle plasma membrane.
67. Insulin action is initiated by the binding of insulin to its receptor, and an increase in:
a. serine phosphorylation of the b subunit of the receptor.
b. tyrosine phosphorylation of the a subunit of the receptor.
c. the activity of tyrosine kinase at the carboxy terminus of the b subunit.
d. the dephosphorylation of insulin receptor substrate-1 (IRS-1).
68. Osteopetrosis is an autosomal recessive disease involving the congenital absence of the gene coding for carbonic anhydrase isoenzyme II. In these individuals, which of the following would be affected?
a. the rate of fusion of preosteoclasts to form osteoclasts
b. the rate of proton pumping via the H+ ATPase and/or the H+-K+ ATPase in the ruffled border of osteoclasts
c. the destruction of mineralization inhibitors within osteoid.
d. the rate of osteocalcin secretion by osteoblasts
e. none of the above
69. Within the time course of osteoblast gene expression, the gene for collagen type I is maximally expressed:
a. during the proliferation phase.
b. during the phase of matrix maturation.
c. during the mineralization phase.
d. at the same time as transforming growth factor b (TGF-b ).
e. both a and d
70. Hydroxyapatite (HAP) crystals:
a. are secreted from osteoblasts.
b. are only found in bones and teeth.
c. increase in number as a given microvolume of bone tissue calcifies.
d. are bound to osteoblast plasma membranes via osteopontin.
e. both c and d
71. As plasma PO43- is increased above normal (hyperphosphatemia), which of the following would occur?
a. 1-hyroxylase activity in proximal tubule cells would increase
b. calcitonin secretion would increase
c. plasma Ca2+ would increase in corresponding fashion
d. PTH secretion would be stimulated
e. both b and c
72. Under conditions of normal plasma calcium, which of the following would stimulate PTH secretion from chief cells?
a. IP3 induced calcium release from intracellular stores
b. phosphodiesterase inhibitors
c. agents which stimulate phospholipase C activity
d. membrane permeant cAMP agonists
e. both b and d
73. PTH input to proximal tubule cells of the kidney will:
a. increase the rate of Ca2+ entry across the apical membrane.
b. decrease the rate of Ca2+ entry across the apical membrane.
c. increase the rate of PO43- entry across the apical membrane.
d. decrease the rate of PO43- entry across the apical membrane.
e. both a and d
74. Which of the following conditions involve elevated PTH?
a. vitamin D resistent osteomalacia
b. Type II hereditary vitamin D dependent osteomalacia
c. vitamin D toxicity due to inadvertent administration of exogenous calcitriol
d. hypercalcemia of malignancy
e. hypoparathyroidism
75. An adult patient presents with symptoms of hypocalcemic tetany. Lab tests confirm that plasma calcium is low, and also indicate that plasma phosphate is elevated but plasma PTH and calcitriol are low. Which of the following additional lab test would be most useful in determining the cause of this disorder?
a. measuring plasma Mg2+
b. measuring plasma PTHrp
c. measuring plasma calcitonin
d. measuring plasma calcitonin gene related peptide
e. None of the above tests would be useful.
76. An adult patient presents complaining of bone pain. Radiological evaluation reveals excessive bone resorption and abnormally thick osteoid regions. Lab tests show plasma calcium and calcitriol are elevated but plasma phosphate and PTH levels are low compared to normal. Which of the following conditions is consistent with these findings?
a. hypoparathyroidism
b. excess vitamin D (calcitriol)
c. vitamin D dependent osteomalacia
d. vitamin D resistent osteomalacia
e. both b and d
77. Fatal hypocalcemia usually results from:
a. internal bleeding due to failure of blood clotting.
b. an inability to contract the abdominal diaphram.
c. an inability to generate action potentials within the nervous system.
d. constriction of airways leading to asphyxia.
e. both b and c
78. For an individual with a chromosomal complement of 46,XX to develop into a phenotypic man, which of the following genes must have been transferred to the second X chromosome during an abnormal cross-over?
a. the gene for the HY antigen
b. the gene for androgen receptors
c. the gene for 5a -reductase
d. the SRY gene
79. Fallopian tube formation is dependent on:
a. estrogens.
b. chorionic gonadotropin.
c. progesterone.
d. the absence of anti-mullerian hormone.
e. all of the above
80. Sertoli cells:
a. respond to FSH by releasing protease inhibitors.
b. are stimulated by hSCSP-80 to increase the secretion rate of androgen binding protein.
c. affect Leydig cell testosterone secretion through the inhibition of LH secretion by gonadotropes.
d. possess androgen receptors.
e. none of the above.
81. The vast numbers of spermatozoa produced by a normal man result from the mitotic activity of:
a. Type A-pale spermatogonia.
b. Type A-dark spermatogonia.
c. Type B spermatogonia.
d. Primary spermatocytes.
e. Secondary spermatocytes.
Questions 82-84 pertain to three different male patients who report that they and their respective wives have failed to conceive following a whole year of regular sexual intercourse without contraception. Suspecting that these men may in fact, be infertile you order lab tests involving a semen analysis and blood tests following 72 hours of abstinence. Answer the following for each case.
82. Lab results for patient 1 indicate a reduced sperm count (oligospermia) and reduced plasma concentrations of testosterone, FSH, and LH. Which of the following conditions is consistent with these lab results?
a. an overproduction of Sertoli cell inhibin
b. a congenital absence of activin by Sertoli cells
c. increased serum estrogens derived from aromatization of testosterone in the peripheral tissues
d. a tumor resulting in hypersecretion of prolactin
e. all of the above are consistent with these lab results
83. Lab results for patient 2 indicate oligospermia and low plasma concentrations of testosterone, but elevated LH and FSH. Which of the following conditions is consistent with these lab results?
a. hypogonadism associated with androgen insensitivity
b. hypogonadism associated with cryptorchidism
c. hypogonadism associated with seminiferous tubule failure
d. hypogonadotropic hypogonadism
e. none of the above are consistent with these lab results
84. Lab results for patient 3 indicate oligospermia and a reduction in the ejaculate volume, but normal plasma concentrations of testosterone, LH, and FSH. Which of the following conditions is consistent with these lab results?
a. retrograde ejaculation
b. hypogonadism associated seminiferous tubule failure
c. disruption of the innervation to the prostate gland
d. disruption of the innervation to the seminal vesicles
e. all of the above are consistent with these lab results
85. Which of the following could account for semen samples that have normal sperm counts, but have relatively low total volumes and a pH of around 7.3?
a. the duct to one seminal vesicle is blocked
b. the majority of ducts draining prostatic glands are blocked
c. the individual is experiencing retrograde ejaculation
d. there is a congenital absence of the bulbourethral glands
e. none of the above
86. Infusion of exogenous testosterone to a normal, fertile man results in:
a. an increase in the transcription rate of b -subunits within gonadotropes.
b. an increase in the rate of synthesis of sex steroid binding globulin (SSBG).
c. a decrease in the sperm count contained within an ejaculate.
d. an increase in GnRH available to gonadotropes.
e. both a and d are true.
87. With regard to the menstual cycle, which statement is false?
a. An anovulatory cycle is always characterized by high estrogens during the follicular phase and low progesterone during the second half of the cycle.
b. Replacement therapy with estrogen and progesterone can be recommended in cases where serum FSH levels are higher than normal.
c. During the menstrual cycle the highest ratio of FSH to LH is reached during menstruation.
d. Inhibin and activin exert opposite effects on theca cells of antral follicles.
88. With regard to female reproductive function, which of the following statements is true?
a. Estrogens, progesterone and prolactin stimulate development of the mammary ductal system.
b. Serum measurements of estrogen can inform the clinician about the health of the placenta and fetus during pregnancy.
c. Studies of reproduction patterns in various tribes have yielded a better correlation between the length of periods between pregnancies and the frequency of breast feeding episodes, as opposed to the actual length of each breast feeding.
d. All of the above statements are true.
89. Which of the following statements is false?
a. Body temperature reaches its highest level during the second half of the menstrual cycle.
b. Resumption of the first meiotic division is triggered by the pre-ovulatory surge in LH.
c. Estrone is an inactive estrogen precursor.
d. Angiotensin II and fibroblast growth factor are some of the factors with angiogenic properties that are present in the follicular fluid at the time of ovulation.
90. Which of the following statements is true?
a. Dehydroepiandrosterone sulfate is a progesterone precursor.
b. LH stimulates activitiy of the aromatase enzyme which converts androgens to estrogens.
c. Increased responsiveness to pituitary GnRH is observed during the late follicular phase of the menstrual cycle.
d. None of the above statements is true.