Exam 3 – Posted Answers BISC 307L - General Physiology April 6, 2012 1. Hypercalcemia would likely result in increased… (c) a. reabsorption of Ca2+ in the kidneys. d. excitability of neurons. b. secretion of parathyroid hormone. e. osteoclast activity. c. secretion of calcitonin. 2. Which one of the following would not cause hypocalcemia? (d) a. chronic kidney failure b. a vitamin D deficiency c. damage to parathyroid glands during surgery to remove thyroid tumors d. a mutated parathyroid hormone receptor that auto-activates even in the absence of PTH 3. You and other third year medical students are accompanying the attending endocrinology physician on her rounds. She introduces you to a patient with an adenoma (tumor) of the parathyroid gland that secretes excess parathyroid hormone. To your horror, she asks you to explain to the group the symptoms this patient is likely to have. Which of the following symptoms would you expect? Note: Write as many letters in the box as you think apply, but don’t guess because points will be deducted for wrong answers. Don’t worry; you can’t get less than zero. a. hypocalcemia f. elevated free Ca2+ in cells (>10-5 M) b. kidney stones g. abnormal growth of bones c. depressed brain activity h. loss of bone density d. hyperexcitable skeletal muscles i. high levels of calcitriol in plasma e. high levels of Ca2+ in the urine j. low levels of prolactin secretion 4. Which of the following structures in men and women are least alike in function or embryological origin? (e) a. testes & ovaries d. spermatogonia & oogonia b. vas deferens & oviduct e. seminiferous tubules & vagina c. scrotum & labia majora f. sertoli cell & granulosa cell 5. Which one of the following statements about reproduction is false? (d) a. The corpus luteum secretes both estrogen and progesterone. b. The secretion of FSH in men is directly inhibited by inhibin secreted from Sertoli cells. c. The fast block to polyspermy is a Ca2+-dependent action potential that occurs in the oocyte membrane upon fertilization. Answer in box. ANS: b, c, h, i (+1 for each correct, -1 for each wrong) 4 pts. 4 pts. 3 pts. 3 pts. 4 pts.NAME__________________________________ 2 d. Once fully-formed sperm enter the epididymus for storage, they undergo capacitation, which a necessary step in preparation for fertilization. e. Baby girls are born with approximately 2 million primary follicles, each consisting of an oocyte surrounded by a single layer of granulosa cells. 6. Which one of the following statements about the endocrine control of male reproduction is true? (a) a. FSH receptors are located on Sertoli cells. b. Sertoli cells secrete testosterone. c. LH receptors are located on Sertoli cells. d. Spermatogonial cells have receptors for both FSH and LH. 7. A newly formed human zygote has a sufficient supply of energy to survive for about 1 day on its own. However, the delay between fertilization and implantation of the blastocyst can be as long as 8 days. What mechanisms sustain the zygote for such a long time? ANS: Under the influence of progesterone and estrogen (or estradiol) secreted by the corpus luteum during the second half (luteal phase) of the ovarian cycle, the uterus enters its secretory phase. During this time the endometrium and the cells lining the oviducts produce high levels of glycogen and other nutrients. Some of this is secreted in the form of a glycogen-rich mucus called uterine milk, which nourishes the embryo until implantation. 8. Which one of the following changes does not normally happen in the circulatory system of a newborn baby within a few minutes of birth? (b) a. Pulmonary vascular resistance decreases. b. Resistance of the ductus arterious decreases. c. Saturation of the blood with oxygen increases. d. Peripheral resistance increases due to elimination of the placenta. e. Pressure in the left atrium becomes higher than pressure in the right atrium. 9. A 46-year-old male patient with multiple autoimmune diseases developed an autoantibody against the FSH receptor that blocked FSH activity. Indicate whether each of the following statements is likely to be true or false by writing the word “True” or “False” in the blank. Do not write T or F. ___________ a. Plasma levels of inhibin will be higher than normal. (F) ___________ b. Plasma levels of FSH will be higher than normal. (T) ___________ c. Plasma levels of activin will be lower than normal. (T) ___________ d. The sperm count will be lower than normal. (T) 10. Shown below are two identical tubes. Tube A has a milk shake solution flowing through it, and tube B has milk flowing through it. Hydraulic pressures at the upstream and downstream ends of the tubes are indicated. Is the flow rate (volume/time) equal in both tubes, higher in tube A, or higher in tube B? Thoroughly explain your answer. Milk Shake 110 mm Hg 80 mm Hg Tube A Milk 55 mm Hg 25 mm Hg Tube B 3 pts. 6 pts. 4 pts. 4 pts. 6 pts.NAME__________________________________ 3 ANS: Flow rate is higher in tube B. Flow rate equals pressure divided by resistance. The pressure gradient is the same for both tubes, (110 - 80) = (55 – 25) = 30 mm Hg. Resistance (R) however is lower for tube B. According to Poiseuille’s Law, R = 8L / r4 or R  L / r4. Length (L) and radius (r) is the same for both tubes, but the viscosity  is lower for the milk in tube B than for the milk shake in tube A. Since resistance is proportional to viscosity, the milk in tube B encounters less resistance. 11. Which one of the following factors would decrease peripheral resistance? (c) a. dehydration b. arteriolar vasoconstriction c. decreased sympathetic nerve activity d. atheromatous plaques in systemic arteries e. increased secretion from chromaffin cells in adrenal medulla f. polycythemia vera (excessive red blood cell production in the bone marrow) 12. Each of the drugs below is potentially useful in the treatment of tachycardia (rapid heart rate) or bradycardia (slow heart rate). In each blank, write T if the drug could be used to treat tachycardia, or write B if the drug could be used to treat bradycardia. _________ a. Propranolol (a non-selective -adrenergic receptor blocker) -T _________ b. Adenosine (increases K+ permeability of sinoatrial node cells) -T _________ c. Epinephrine (natural ligand of adrenergic receptors) -B _________ d. Disopyramine (blocks