Biology 2100 Human Physiology Name: KEY C. Iltis SLCC March 8, 2000 Midterm Examination #2 Multiple Choice Questions (2 POINTS EACH) 1. When glucose levels are above 100 mg/dl, which of the following is true? a. Glucagon is released from alpha cells of the pancreas b. Insulin is released from alpha cells of the pancreas c. Glucagon is released from beta cells of the pancreas d. Insulin is released from beta cells of the pancreas e. Somatostatin is released from delta cells of the pancreas 2. The zona glomerulosa of the adrenal cortex produces: a. mineralcorticoids b. glucocorticoids c. androgens d. A and B e. B and C 3. Which of the following hormones stimulates development of mammary glands and production of milk? a. gonadotropin b. FSH c. LH d. prolactin e. oxytocin 4. Mineralcorticoid is to aldosterone as glucocorticoid is to: a. epinephrine b. insulin c. cortisol d. testosterone e. progesterone 5. Which of the following hormones acts on Interstitial cells of Leydig in the male to increase production of testosterone? a. GnRH b. epinephrine c. LH d. Prl e. FSH 6. Which of the following hormones stimulates ovulation in females? a. GnRH b. epinephrine c. LH d. Prl e. FSH 7. Which of the following is a change that may be caused by a hormonal stimulus? a. the stimulation of a genetic event (transcription) resulting in protein synthesis b. an increase in enzymatic activity c. a change in membrane potential d. activation of a G protein within the plasma membrane e. all of the above are correct 8. NSAIDs such as aspirin and ibuprofen act as anti-inflammatory agents by inhibiting the production of chemical agents that are: a. derivatives of tyrosine b. derivatives of arachidonic acid c. derivatives of retinoic acid d. derivatives of phospholipase C e. derivatives of prostacyclins 9. An individual motor neuron and all the fibers it innervates is called a: a. motor unit b. neuromuscular unit c. neuromuscular junction d. motor junction e. neuromuscular bundle 10. Inadequate intake of this mineral in the diet causes goiter a. sodium b. iron c. iodine d. potassium e. calcium 1
11. Angiotensin II: a. stimulates kidney cells to release aldosterone b. stimulates kidney cells to release renin c. stimulates the liver to release more angiotensinogen d. inhibits ADH release from the posterior pituitary e. none of the above are correct 12. Growth Hormone: a. release is stimulated by GnRH b. secretion results in a decrease in muscle mass c. promotes long bone growth d. all of the above e. a and c only 13. ADH a. increases urine production b. promotes dehydration c. is produced in the posterior pituitary d. is inhibited by alcohol e. all of the above are correct 14. The supraoptic and paraventricular nuclei are located in the: a. posterior pituitary b. adrenal medulla c. anterior pituitary d. hypothalamus e. thalamus 15. The only amine hormone which acts like a steroid is: a. TH b. ACTH c. GH d. ADH e. epinephrine 16. Which of the following are hormones whose release is stimulated by stress? a. epinephrine b. cortisol c. norepinephrine d. aldosterone e. all of the above 17. Which of the following endocrine glands is composed of BOTH neural and epithelial tissue? a. Hypothalamus b. Islets of Langerhans c. adrenal glands d. Thyroid gland e. both A and C are correct 18. In circumstances where the body requires increased response to a particular circulating hormone, the target cells may synthesize more receptors for that hormone and place them on the cell surface. This process is known as: a. a sensitivity reaction b. downregulation c. stressor regulation d. upregulation e. facilitation 19. Eicosanoids do NOT include: a. thromboxanes b. prostaglandins c. hydrocortisones d. leukotrienes e. all of the above ARE classified as eicosanoids 20. which of the following is the limiting factor which determines the duration of a muscle twitch? a. type of myosin ATPase b. strength of the stimulus c. length of the muscle fiber d. amount of sarcoplasmic reticulum e. none of the above 21. Immediately following the arrival of a stimulus at a neuromuscular junction there is a short period called the period during which the events of excitation-contraction coupling occur. a. contraction b. relaxation c. latent d. refractory e. twitch 2
22. A kinase is: a. an enzyme that splits ATP b. an enzyme that phosphorylates ATP c. an enzyme that phosphorylates proteins d. an enzyme that cleaves proteins. 23. Which of the following categories of chemical messengers act as paracrine agents? a. prostaglandins b. thyroid hormones c. steroid hormones d. catecholamines e. tyrosine derivatives 24.Which of the following is NOT a common second messenger within cells? a. G protein b. IP3 c. camp d. DAG e. Calcium 25. camp is: a. Formed from ATP by the enzyme adenylyl cyclase b. Generated intracellularly via a G-protein linked system. c. Responsible for activating protein kinases within a cell. d. All of the above are correct. e. Only A and C are correct. 26. The hormone secreted by the parafollicular cells of the thyroid is: a. T3 & T4 b. vasopressin c. calcitonin d. thymosin e. parathormone 27. Which of the following hormones is NOT produced by the anterior pituitary? a. LH b. FSH c. GH d. ADH e. ACTH 28. Individuals with type II diabetes: a. have an absolute requirement for insulin injections b. don t produce adequate amounts of insulin. c. have insulin receptors that are unresponsive to insulin d. may often control their disease by diet and exercise e. both c and d are correct 29. The anterior pituitary is often referred to as the master endocrine gland. What gives this small gland this distinction? a. It is the only gland producing catecholamines b. Its products regulate the release of hormones by other endocrine glands c. Its products stimulate sperm production in the testes. d. Its products control the phases of the menstrual cycle in females e. Both c and d are correct Questions 30-34: Match the definition in Column A with the corresponding word from Column B. Column A Column B 30. A contraction in which the muscle shortens e a. isometric 31. A contraction in which the muscle lengthens b b. eccentric 32. A contraction in which the muscle does not change length a c. tetanic 33. The type of contraction which follows a single action potential d d. twitch 34. The type of contraction which follows a series of action e. concentric potentials delivered at a rapid rate to the muscle. c 3
35. A force-velocity relationship for skeletal muscle demonstrates that: a. When muscle force is maximal, muscle velocity is zero. b. There is an inverse relationship between muscle force and velocity of contraction c. When muscle velocity is maximal, muscle force is zero. d. all of the above e. a and c only Matching (1 POINT EACH) Answer the following questions on the BACK of your scantron form. Match the correct muscle fiber type in column 2 with the description in column 1. The answers in column 2 will be used more than once. Column 1 Column 2 51. Rely primarily on glycolysis for energy production. c A. Type I 52. Rely primarily on oxidative metabolism for energy production. a B. Type IIa 53. Rely both on glycolysis and oxidative metabolism for energy production. b C. Type IIb 54. Have the fastest myosin ATPases. c 55. Have an abundant sarcoplasmic reticulum. c 56. Compose the smallest motor units. a 57. Are abundant in postural muscles. a 58. A high percentage of these fibers would be found in sprinters. c 59. Have fast myosin ATPases and are highly resistant to fatigue. b 60. Would be the last fiber types to be recruited during a muscular contraction. c 4
Essay/Short Answer Questions (6 points) 1. The graph below is a recording of a muscle twitch. In the spaces provided, label the periods A, B and C. Then, in the space below, describe the intracellular events which are occurring during each of the labeled phases. A B C A = Latent Period Description of events: The events of excitation-contraction coupling are taking place, leading to the release of Calcium from the SR. B = Period of Contraction Description of events: Crossbridges are cycling and the muscle is producing force. C = Period of Relaxation Description of events: Calcium is being pumped back into the sarcoplasmic reticulum. 5
(8 points) 2. Below is a typical force-length graph for skeletal muscle. For each of the major portions of the graph, explain why the force is rising, falling or staying the same in terms of what is happening at the level of the individual sarcomere. A. 60-80 percent of resting length. (Why is the force zero at 60% resting length?) Muscle force is low because of a low number of cross-bridges that can interact. In addition, some crossbridges are attached to the wrong actin filament so are pulling the wrong direction. At 60% of resting length the force is zero because the thin filaments have run into the Z lines and there are not enough active crossbridges to create significant force. B. 80-100 percent of resting length. The overlap of thick and thin filaments is greater than at 60 80% of resting length so muscle force has increased significantly. However, there is still a suboptimal overlap between thick and thin filaments so force is not maximal. C. 100-120 percent of resting length. (Why is the force maximal in this range?) Maximal force is produced by the muscle due to optimum overlap of thick and thin filaments. This sarcomere length corresponds to the normal resting length of the muscle in vivo. Because the largest number of crossbridges are able to produce force with this amount of overlap, the muscle force is maximal. D. 120-180 percent of resting length. (Why is the force zero at 180 percent resting length?) The sarcomere is so long that there is little overlap between thick and thin filaments, so less force is produced. AT 180% of resting length there is no overlap between thick and thin filaments. Thus, muscle force is zero. 6
(6 points) 3. Describe the camp second messenger system for hormone action. Begin with hormone/receptor binding and end with phosphorylation of a protein within the cell. In addition to describing the process in words, draw a diagram depicting the process. See your notes for the answer to this question. 7
(5 points) The following four questions relate back to Essay Question #3 and second messenger systems. 4. What class of hormone works via the camp second messenger mechanism? Peptides & amines 5. Where in the process described above does amplification occur? Answer: The steps including activation of adenylyl cyclase, the camp dependent protein kinase, etc. 6. Why is amplification important? Answer: It allows the binding of a single hormone molecule to result in the phosphorylation of thousands of proteins within the cell. 7. What TWO classes of hormones do NOT act via second messenger systems? a. Thyroid hormones b. Steroid hormones 8