HBY 531 Organ
Systems
Final
Examination
2000
Section 1: Answer the following using:
A = increases, increased
B = remains the same, the same
C = decreases, decreased
1. The H+ secretion rate in parietal cells _________ in response to GIP.
2. The diameter of the ileocolonic sphincter _______ after an elevation of plasma levels of epinephrine. ()
3. The absorption of glucose _________ in response to an increase in the intracellular Na+ levels in columnar absorptive cells. ()
4. The intracellular free Ca2+ concentration in parietal cells _______ after a rise in gastrin levels. ()
5. The secretions of the parietal cell ________ in response to distension of the stomach.
6. Gallbladder
motility _________ as a result of exposure to elevated levels of CCK.
7. The diameter of the sphincter of Oddi _________ as a result of exposure to elevated levels of CCK.
8. During the absorptive state, the plasma LDL concentration __________ as a result of changes in the chylomicron concentration.
9. The motility of
the pyloric stomach ________ as a consequence of elevated gastrin levels.
10. A patient presents with symptoms of hypercortisolism. If this patient had been taking a large dose of dexamethasone (a potent glucocorticoid) for many weeks, you would expect that
her early morning (i.e., 4AM) serum ACTH levels would be ________ compared to normal.
11. With regard to the same patient described in question 10 taking large doses of dexamethasone for many weeks, you would expect that her serum ACTH level would be _______ after a low dose dexamethasone test.
12. If a patient suffered from a dysfunction in her hypothalamic-pituitary axis (Cushing’s Disease), then you would expect that it is likely that this patient’s late afternoon (4PM) serum ACTH would be __________ after a high-dose dexamethasone suppression test.
13. With regard to the same patient described in question 12, you would expect that the 4PM serum ACTH would likely be _______ after a low-dose dexamethasone suppression test.
14. 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. DHEA synthesis in a patient taking this drug would be ________.
15. Serum ACTH in the late afternoon in a patient with a normal hypothalamic-pituitary axis taking metyrapone would be _______ relative to normal.
16. The secretion rate of glucagon ___________ following an increase in circulating levels of somatostatin.
17. The rate of glucose utilization within cells _________ following an increase in circulating levels of somatotropin.
18. Urinary Ca2+ excretion ________________ following treatment with a thiazide diuretic.
19. Compared to a normal diet, urinary phosphate excretion ________________ during the course of a high phosphate diet.
20. The secretion rate of osteoblasts ________________ following exposure to calcitriol.
21. The solubility of hydroxyapaptite __________________ during acidosis.
22. Androgen binding protein (ABP) synthesis within Sertoli cells ______________ upon activation of FSH receptors.
23. The Na+ concentration within the adluminal compartments of seminiferous tubules ____________ following disruption of the blood-testis barrier.
24. The plasma LH level ___________ following a fall in circulating testosterone levels.
25. The fructose content of semen _____________ following blockage of the ducts of the seminal vesicles.
26. During menopause, the plasma levels
of FSH and LH are __________ compared to what they are before menopause.
27.
During pregnancy, aldosterone production ___________ in response to
progesterone.
28. The LH receptor density on theca cells _________ in response to exposure to estrogen.
29. The rate of cell division of granulosa cells _________ after exposure to LH.
Section 2: For each of the following,
choose the single best response.
Use the following hypothetical case to answer questions 30 and 31:
A patient complains that their mouth is always dry or feels dry. You sample the fluid in the oral cavity under two conditions: no food stimulus (low flow rate) and with a food stimulus (high flow rate). In addition, you sample your own salivary output under the same two conditions. For all four samples you determine the inorganic composition and pH. For comparison you compare the data to plasma levels of the same ions. The data below are the results all in units of mM (except for pH).
Data collected:
Saliva
Flow Rates
You (Normal) Patient
Normal Plasma: Low High Low High
Na+=140 25 90 100 110
K+= 4 25 15 10 8
Cl-=100 10 50 40 90
HCO3-= 24 20 40 20 20
pH=7.24 7.15 6.8
30. Which of the following defect(s) is (are) possible?
a. The K+/H+ exchangers of the duct cells are dysfunctional.
b. The anion channels in the acinar cell are dysfunctional.
c. the Cl-/HCO3- exchangers in the duct cells are dysfunctional.
d. the tight junctions are leaky even in the ducts.
e. a and c are true.
31. Utilize the data from the previous question. The elevated Na+ level in the patient’s saliva relative to YOUR saliva is:
a. due to poor resorption by the Na+/H+ exchanger.
b. consistent with the more acidic saliva of the patient.
c. a consequence of excessive carbonic anhydrase activity.
d. not an important manifestation of the condition.
e. a and b are true.
32. The sources of intestinal secretions arising from the small intestine itself:
a. are from the Brunners glands.
b. stem from Cl- efflux from crypt cells.
c. stem from goblet cells in the epithelial lining.
d. arise from all of the above.
33. The unstirred layer:
a. is a consequence of the glycocalyx only.
b. limits access to the surface of columnar absorptive cells.
c. is traversed on the basis of diffusion and not convection.
d. All of the above are true.
34. In a crypt cell the intracellular Cl- is 30 mM and in the lumen its 130 mM. Recall that ECl=25 ln(Clcell/Cllumen). The resting potential of the cell is –50 mV.
a. ECl is –50 mV.
b. Activation of Cl- channels would result in an efflux of Cl- cytoplasm to lumen.
c. a and b are true.
d. When ECl is equal to the resting potential, Cl- will influx from lumen to cytoplasm.
35. Consider the pervious case (i.e., question 34). If the luminal Cl- concentration decreased from 130 to 50 mM, and all other parameter remain the same, then
a. ECl is –20
mV.
b. activation of Cl- channels would result in a larger efflux of Cl- from cytoplasm to lumen compared to the case described in question 34.
c. activation of Cl- channels would result in a lesser efflux of Cl- from cytoplasm to lumen compared to the case described in question 34.
d. neither Cl- influx nor efflux would occur if Vm was equal to –30 mV.
36. With respect to HDLs, which of the following is FALSE?
a. HDLs can be synthesized by columnar absorptive cells.
b. HDLs can be synthesized by liver hepatocytes.
c. HDLs are the densest lipoproteins.
d. HDLs have apoE as a major component.
37. Lactose intolerance:
a. will result in secretory diarrhea if large amounts of diary products are consumed.
b. occurs in persons with a low Na+ intake.
c. occurs when there is insufficient lactase enzyme functioning on the columnar absorptive cell.
d. a and b are true.
38. The columnar absorptive cells of the ileum
a. contain Na+/bile salt transporters.
b. contain no Cl-/HCO3- exchangers.
c. contain no Na+/HCO3- transporters.
d. contain no fructose transporters.
39. The small intestine will absorb/resorb:
a. 50% of the total secreted and ingested fluids.
b. 95% of the total secreted and ingested fluids.
c. no magnesium.
d. calcium via apically placed calcium channels on columnar absorptive cells.
e. b and d are true.
Answer questions 40-43 using the data provided graphically .
An individual has ingested 1000 mL of fluids with a pH of 7.1 at the 1-hour mark. You are monitoring stomach pH, stomach volume and small intestine volume.
40. The reduction in small intestine volume
between 1.5 and 2 hours is due to:
a. the gastrocolonic reflex.
b. gastro-gastric reflex.
c. defecation.
d. gastroileal reflex.
41. The moles of H+ produced at the 2.5-hour mark is:
a. 2x10-6
moles.
b. 2x10-4 moles.
c. 2x10-5 moles.
d. none of the above.
42. Secretion volume arising from the small intestine, liver and pancreas is:
a. 0.5 L.
b. 1.5 L.
c. 3.5 L.
d. 4.0 L.
43. With regard to the data which of the following is true?
a. The declining slope of the small intestine volume between the 30-minute mark and 1.5-hour mark is due to solute and solvent absorption/resorption.
b. The duration of receptive relaxation is 3 hours long.
c. There is no way to determine from the data if the coloncolonic reflex is functioning.
d. a and c are true.
44. The addition of a radioactively-tagged fatty acids to a normal rat diet would NOT be expected:
a. to appear in chylomicrons and then in adipose after apoprotein C2 removal by HDL.
b. to appear in HDL after hydrolysis of chylomicron triglycerides in adipose tissues.
c. to appear in LDL particles after clearance of VLDL remnants by the liver.
d. to appear in chylomicron remnant particles, then in liver.
45. The activation of adenylate cyclase in liver by glucagon would increase:
a. liver fructose-2,6-bisphosphate levels.
b. rates of glycogen synthesis.
c. mRNA levels of PEPCK (phosphoenolpyruvate carboxyinase).
d. phosphofructo-1-kinase phosphorylation.
46. Insulin affects the uptake of glucose into cells by
a. increasing the mRNA of glucokinase in liver.
b. increasing the recruitment of GLUT-2 to the plasma membrane.
c. decreasing the Km of GLUT-4 for glucose.
d. increasing the rate of oscillations of the transporter.
47. An adolescent complains of frequent urination, and thirst. A subsequent glucose tolerance test showed elevated fasting and two hour blood glucose levels. The patient can be tentatively diagnosed with:
a. NIDDM if immunoreactive insulin levels in the blood are elevated after 2 hr.
b. IDDM if immunoreactive insulin levels in the blood are elevated after 2 hr.
c. NIDDM if Islet Cell Antibodies (ICA) are detected in the blood.
d. IDDM if connecting (C-) peptide to insulin ratios in the blood are low.
48. You are on an “All-protein diet” with literally no carbohydrate. Under these conditions,
a.
your blood
insulin levels should decrease, to prevent further hypoglycemia.
b. your blood insulin and glucagon should both increase, unless you are an IDDM.
c. your blood glucagon levels should increase, unless you have a mutation in your glucagon.
d. your adipose tissue stores will be depleted because of increased lipoprotein lipase activity.
49. Glucagon regulates carbohydrate metabolism in liver by causing the phosphorylation of several key enzymes, which one of the following enzymes is activated by phosphorylation?
a. Fructose-1,6-bisphosphatase
b. Phosphofructo-2-kinase
c. Glycogen synthetase
d. Phosphorylase kinase
50. The transcription of several genes is enhanced by an increase in intracellular cAMP levels which is mediated by the phosphorylation of the cyclic AMP Regulatory Binding Protein (CREB). Which of the following are subject to this form of regulation?
a. PEPCK
b. Glucokinase
c. Phosphofructo-2-kinase
d. Pyruvate kinase
51. The addition of a high concentration of glucose to a culture of isolated islets of Langerhans
would be expected to:
a.
decrease
insulin secretion only if basic amino acids are also present in the culture
medium.
b. increase insulin secretion only if Ca2+ is also present in the culture medium.
c. increase insulin secretion only if intracellular cAMP levels are also increased.
d. increase insulin secretion only if K+ is in the culture medium.
52. A comatose patient was admitted with severe hypoglycemia (low blood glucose), he is immediately given glucagon intravenously. After 10 min blood glucose levels have still not returned to normal. Which of the following is a possible explanation?
a. The patient has very low glucose-6-phosphatase activity as a result of heredity.
b. The patient has depleted all muscle and liver glycogen stores.
c. The patient has eaten only protein for several days before the coma.
d. The patient has inherited a defective insulin receptor gene.
53. Which of the following statements is FALSE?
a.
Ketone
bodies are water soluble, requiring no transporter in blood.
b. The connecting (C)-peptide of insulin is cleared from circulation at about the same rate as insulin.
c. Human red blood cells rely exclusively on glycolysis for energy, because they have no mitochondria.
d. Pancreatic somatostatin inhibits insulin as well as glucagon release.
54. Which of the following statements about thyroxine is true?
a. T4 is converted to MIT and DIT (mono and di-iodotyrosines) in the liver where it is bound to albumin to be transported in the blood.
b. T4 binds to the TRH and TSH receptor on the plasma membrane of nerve cells in the brain to allow normal growth and development.
c. T4 is used to transport iodide through the thyroid cell plasma membrane to the colloid.
d. The major biological activity of T4 in cells is dependent on deiodinase expression.
55. In a patient suffering from hypothyroidism caused by destruction of the thyroid gland, which of the following would be expected to be found in this patient?
a. An increased systolic pressure with a relatively low diastolic pressure (large pulse pressure).
b. A warm wet skin with a dislike for warm temperatures.
c. An increase in the basal metabolic rate.
d. Increased TSH blood levels.
56. “Autoregulation” as applied to thyroid gland physiology refers to:
a. when an increase in the oral intake of iodides produces a marked decrease in the synthesis and release of T4 by an over-stimulated thyroid gland.
b. when a marked increase in the oral intake of iodides increases the activity of an already over-stimulated thyroid gland.
c. when in the absence of any intake of iodides the thyroid gland upregulates its “iodide trap” to make use of any available iodide for synthesis of iodinated thyroglobulin.
d. when the intracellular conversion of T4 to T3 is increased with starvation.
57. A patient suffers from “Addison’s Disease”. In this case it is the autoimmune mediated-destruction of the adrenal cortex that produced the disease. In this patient you would expect
a. a low level of ACTH and growth hormone in the blood during the sleep period.
b. little response by the adrenal medulla to release adrenalin (epinephrine) to the stimulus of a significantly low blood sugar.
c. retention of sodium ions and water producing moderate edema particularly of the face.
d. a low blood pressure that is inadequate for the body’s need accompanied by a lower than normal blood sugar particularly between meals.
58. The Adrenogenital Syndrome is the term given to a group of diseases in which there are congenital enzyme deficiencies in pathways of adrenocortical hormone synthesis. 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 with a deficiency of the 21-hydroxylase enzyme you might find:
a. high levels of circulating aldosterone and a low level of blood potassium ion.
b. decreased levels of ACTH, particularly at the 4AM sample.
c. decreased growth of hair and very late maturation of bone growth.
d. the treatment usually consists of a glucocorticoid such as Dexamethasone which satisfies the bodies need for cortisol and decreases the higher than normal ACTH levels that are found in this disease.
59. Many hormones bind to blood proteins. This binding serves several purposes and has consequences. Among these are:
a. binding to protein makes the hormone more readily accessible to the interior of the target cell as there are specific plasma membrane transporters for the hormone protein complex.
b. binding to protein makes the hormone more easily excreted in the urine.
c. it is usually not necessary to measure “free hormone” in the blood as all the biologic-action is in the complex.
d. binding, in some cases, provides a “reservoir” of hormone and as such can serve to “buffer” acute changes in hormone secretion by the gland.
60. Which of the following is an effect of growth hormone?
a. It sensitizes fat cells to the effect of adrenalin to increase the release of free fatty acids.
b. It sensitizes muscle to the effect of insulin to increase the uptake of glucose by these cells.
c. In excess amounts it produces a thinning of the skin and decreases the size of internal organs such as the liver, heart and kidneys.
d. It directly allows the growth of long bones in a linear fashion in children by affecting the cartilage at the growth centers of bone.
61. A man smoked for 30 years. He has developed a bronchogenic (lung) carcinoma. This tumor in this patient also produces excessive amounts of ACTH (ectopic production). In addition to the ravages produced by the carcinoma this patient might also suffer from:
a. bilateral adrenal hypoplasia with signs and symptoms of Addisons Disease.
b. polyuria and polydipsia due to elevated plasma glucose levels.
c. high serum potassium level associated with a low blood pressure.
d. high blood prolactin levels with some minimal milk production.
62. Which of the following directly stimulates release of a hormone from the anterior pituitary?
a. Hyperosmolality.
b. Somatostatin.
c. Suckling by an infant during lactation by the mother
d.
Somatomedins.
63. A man has been taking thyroxine for many years. Recently because of the feelings of fatigue and loss of appetite he doubled his dose of medication. Within four weeks:
a. he noted that he now had a great desire for warm rooms.
b. his TSH blood level was noted to be quite low.
c. his pulse was found to be in the range of 55-60 whereas it had been in the range of 80 before he changed his dose of thyroxine.
d. his blood pressure was now noted to be 100 over 90 whereas it had been in the range of 130 over 80 before he changed his dose of thyroxine.
64. Na+ coupled phosphate transport in the renal proximal tubule will be expected to decrease following:
a. vitamin D intoxication.
b. sudden Mg2+ depletion.
c. the development of vitamin D dependent osteomalacia.
d. the inadvertent removal of all four parathyroid glands.
65. Assuming a constant GFR, the filtered load of Ca2+ at the level of the renal corpuscle will be expected to increase (relative to normal) following:
a. the development of vitamin D resistant osteomalacia.
b. the development of vitamin D dependent osteomalacia.
c. the development of pseudohypoparathyroidism.
d. the inadvertent removal of all four parathyroid glands.
66. Urinary hydroxyproline is expected to increase (relative to normal) in all of the following conditions except:
a. Hypoparathyroidism.
b. Hyperparathyroidism.
c. Type I vitamin D dependent osteomalacia.
d. Type II vitamin D dependent osteomalacia.
67. Which of the following conditions involves simultaneous depression of plasma calcium and phosphate levels (i.e., hypocalcemia and hypophosphatemia)?
a. Hypoparathyroidism
b. Hyperparathyroidism
c. Vitamin D intoxication
d. Vitamin D deficiency
68. A patient with chronic hypercalcemia would benefit from which of the following?
a. Treatment with a loop diuretic like furosemide
b. Being placed on a low phosphate diet
c. Treatment with a calcitonin antagonist
d. Treatment with PTHrp
69. During a cycle of osteoclastic resorption, resorption is terminated as a result of:
a. stimulation by vitamin D.
b. release of TGFb by the osteoclast.
c. a decrease in the pH of the resorption compartment.
d. an increase in extracellular Ca2+ to levels that exceed 8 mM.
70. Osteopetrosis is a relatively rare autosomal recessive disease in which affected individuals lack the gene for carbonic anhydrase isoenzyme II. In these individuals which of the following processes will be most affected?
a. Osteoblast synthesis of non-collagenous proteins
b. Removal of mineralization inhibitors
c. Osteoclast attachment to bone surfaces
d. Acidification of the resorption compartment
71. Which of the following lab findings would be expected in a patient with secondary hyperparathyroidism associated with renal failure?
a. Hypercalcemia
b. Hhypophosphatemia
c. Elevated calcitriol
d. Elevated PTH
72. Which of the following lab findings would be expected in a patient with pseudohypoparathyroidism?
a. Low PTH
b. Elevated calcitriol
c. Hypercalcemia
d. Hyperphosphatemia
73. Which of the following could account for a situation in which a patient’s plasma total calcium concentration is low yet fails to show any signs or symptoms of hypocalcemia?
a. Alkalosis
b. A citrate blood transfusion
c. Hypoalbuminemia
d. Acute hyperphosphatemia due to a crush injury
74. The phenomena of hypocalcemic tetany is most likely attributable to which of the following?
a. A shift in the voltage dependence of Ca2+ channels
b. A shift in the voltage dependence of Na+ channels
c. An decrease in the Ca2+ permeability of axon terminals
d. A change in the Nernst equilbrium potential for Ca2+
75. In men FSH release is stimulated by:
a. activation of androgen receptors on gonadotropins.
b. increased dopamine input to GnRH-neurons of the hypothalamus.