EXAM II Animal Physiology ZOO 428 Fall 2006

Transcription

1 V Eq EXAM II Animal Physiology ZOO 428 Fall 2006 = RT X o. ln( [ zf [ X ) RT p K[K o pna[na o pcl[cl i V = m ln i F pk[k i pna[na i pcl[cl o I = g(v m V eq. ) Q = C m V m Q Driving Force = V m V eq. 10 R2 T2 T1 = ( ) ( ) ) R 1 10 Ionic Species Cation Anion Sign of Driving Force (V m V eq. ) Direction of Ion Flow outward inward inward outward R = J/K.mol T = 310 K F = 96,500 C/mol Total: 100 Points 1. (10 points) An investigator working with an isolated neuromuscular junction preparation prepared the following solution for the extracellular fluid bathing the motor neuron as well as the innervated skeletal muscle cell: In mm the concentrations were 10 NaCl, 4 KCl, 2 CaCl 2. The solution ph was adjusted to 7.4. Solution osmolarity was adjusted by adding an appropriate amount of mannitol (a sugar that does not interfere with the experiment). The investigator then stimulated the motor neuron in order to send action potentials down the axon toward the innervated skeletal muscle cell. Based on your knowledge of muscle physiology and considering the information provided above, please state whether the skeletal muscle cell will contract when the motor neuron action potential reaches the neuromuscular junction under the above-mentioned experimental conditions. Fully support your statement. 1

2 2. (15 points) Our study of physiology this quarter has so far exposed us to at least four different types of action potentials observed in different cell types. These are action potentials seen in neurons, skeletal muscle cells, pacemaker cells of the heart sinoatrial node, as well as action potentials of typical ventricular myocytes. Use diagrams to show the general features of each of these four action potentials. For each diagram, be sure to label the following information: (i) the ion channels responsible for different phases of the action potential, (ii) the value of the membrane potential during different phases of the action potential, and (iii) the duration of the action potential. 2

3 3. (15 points) Fully explain the cross-bridge cycle. Be sure to use diagrams. 3

4 4. (15 points) Fully explain excitation-contraction coupling in cardiac muscle cells. Be sure to use diagrams. 4

5 5. (20 points) CO 2 generated by metabolically active tissue must first be transported in blood before being expired in the lungs. Fully discuss how CO 2 is transported in blood. Be sure to also explain the exchange processes that take place at the level of the systemic capillaries, as well as those at the pulmonary capillaries. 5

6 Multiple Choice 6. (1 point) Hydrostatic blood pressure is lowest in the: (A) Arteries; (B) Arterioles; (C) Capillaries; (D) Venules; (E) Veins. 7. (1 point) Which one of the following is NOT true about the action potential of a ventricular myocyte: (A) Fast voltage-gated Na channels are responsible for the spike phase; (B) Voltagegated Ca 2 channels are responsible for the plateau phase; (C) The permeability to K increases during the plateau phase; (D) Fast voltage-gated Na channels inactivate; (E) All of the above are true. 8. (1 point) During the cardiac cycle, The first heart sound is produced by the closure of the: (A) Bicuspid valve (left atrioventricular valve); (B) Tricuspid valve (right atrioventricular valve); (C) Aortic semilunar valve; (D) Pulmonary semilunar valve; (E) Both right and left atrioventricular valves. 9. (1 point) Choose the correct sequence of conduction of action potentials in the heart: (A) SA node AV node Bundle of His Purkinje fibers Bundle branches; (B) SA node AV node Bundle of His Bundle branches Purkinje fibers; (C) SA node AV node Bundle branches Bundle of His Purkinje fibers; (D) SA node AV node Purkinje fibers Bundle of His Bundle branches; (E) AV node SA node Bundle of His Bundle branches Purkinje fibers. 10. (1 point) In the pre-synaptic axon terminal of a somatic motor neuron, synaptic vesicles are concentrated in highly specialized regions referred to as the: (A) Active zone; (B) Combat zone; (C) Red zone; (D) Green zone; (E) All of the above. 11. (1 point) This band in the sarcomere unit represents the length of the thick filaments. (A) A band; (B) H band; (C) I band; (D) K band; (E) N band. 12. (1 point) How many acetylcholine molecules are required to activate each nicotinic acetylcholine receptor? (A) 1; (B) 2; (C) 3; (D) 4; (E) (1 point) The end-plate potential: (A) Is at the end of the plate; (B) Results from the activation of the nicotinic acetylcholine receptors; (C) Results from the opening of the voltagegated Na channels; (D) Results from the opening of the voltage-gated K channels; (E) All of the above. 6

7 14. (1 point) Cardiac pacemaker cells continuously receive sympathetic and parasympathetic input from the cardiovascular medullary centers of the brain stem. If the parasympathetic input is experimentally severed, which of the following will take place? (A) Heart rate will increase; (B) Heart rate will decrease; (C) Heart rate will not change; (D) Force of contraction of the heart will decrease; (E) Force of contraction of the heart will increase. 15. (1 point) Approximately, this percentage of total blood CO 2 is bound to hemoglobin: (A) 10%; (B) 20%; (C) 30%; (D) 50%; (E) 70%. 16. (1 point) In resting skeletal muscle cells, the myosin-binding site of G-actin is covered by: (A) Tropomyosin; (B) Nebulin; (C) Titin; (D) Ca 2 ; (E) ATP. 17. (1 point) Approximately this percentage of total blood can be found in the venous system of an individual at rest. (A) 5%; (B) 10%; (C) 35%; (D) 65%; (E) 95%. 18. (1 point) The optimal resting length of a skeletal muscle sarcomere allows it to generate the maximum amount of force. What is the optimal length of a typical sarcomere? (A) 2.15 Å; (B) 2.15 nm; (C) 2.15 µm; (D) 2.15 mm; (E) 2.15 m. 19. (1 point) Which of the following is a Ca 2 sensor? (A) Actin; (B) Myosin; (C) Tropomyosin; (D) Troponin; (E) Titin. 20. (1 point) Which of the following are considered structural proteins of the sarcomere? (A) Titin; (B) Nebulin; (C) Tropomyosin; (D) A and B; (E) A, B, and C. 21. (1 point) Every tropomyosin molecule spans over approximately this many G-actin molecules. (A) 1; (B) 3; (C) 7; (D) 10; (E) Which region of the ECG corresponds to the maximum opening of ventricular Na channels? (A) P wave; (B) QRS complex; (C) T wave; (D) None of the above. True or False 23. (1 point) In skeletal muscle contractions, only 80% of the Ca 2 needed for contraction comes from the sarcoplasmic reticulum. 7

8 24. (1 point) A skeletal muscle fiber is a single muscle cell. 25. (1 point) T-tubules are present in skeletal but not cardiac muscle cells. 27. (1 point) Muscarinic acetylcholine receptors found in the SA node of the heart are ligandgated K channels. 28. (1 point) Twitches of ventricular myocytes are all-or-nothing. 29. (1 point) Ca 2 -induced Ca 2 release is seen skeletal muscle cells. 30. (1 point) The Na /Ca 2 exchanger of the heart muscle is a secondary active transporter. 8