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examfrom05 - Name _ NPB101-Sp05 MT2 Multiple Choice...

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Name __________________________ 1 NPB101-Sp05 MT2 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. Note: True-False answer options may be scrambled, i.e. a. False, b. True. 1. In excitation-contraction coupling in both skeletal and cardiac muscle a. ATP is required only for energizing the actin. b. ATP is required only for breaking the actin-myosin cross-bridge. c. ATP is required for both energizing the actin and breaking the actin-myosin cross-bridge. d. None of the above. 2. Statement pair #1: In skeletal muscle, excitation-contraction coupling requires the binding of calcium, released from the lateral sacs of the sarcoplasmic reticulum, to the troponin-tropomyosin complex. This binding unmasks the myosin binding site on actin. Statement pair #2: In smooth muscle, excitation-contraction coupling requires calcium that enters the muscle cell from extracellular fluid through calcium channels. The increase in sarcoplasmic calcium binds to calmodulin, and this complex triggers phosphorylation of myosin enabling myosin to bind to actin. a. Statement pairs #1 and #2 are both true. b. Statement pairs #1 and #2 are both false. c. Only Statement pair #1 is true. d. Only Statement pair #2 is true. 3. Condition: All the muscle fibers in a skeletal muscle are activated with a single stimulus. The contraction of the muscle is isometric. Question: Increasing the load on the muscle for an isometric contraction will increase the tension developed by the contracting muscle. a. True b. False
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Name: ________________________ 2 4. Condition: A muscle is stimulated and contracts isotonically against heavier loads. Question: What will happen to the velocity of shortening of the whole muscle with increases in load? a. Velocity of shortening will not change until the muscle is contracting isometrically. With an isometric contraction the velocity of shortening of the muscle becomes 0. b. The velocity of shortening will decrease becoming 0 when the muscle contracts isometrically. c. The velocity of shortening will increase until the muscle is contracting isometrically. With an isometric contraction the velocity of shortening of the muscle becomes 0. d. The velocity of shortening will decrease, but will never become 0. e. None of the above. 5. Increases in sarcoplasmic calcium in skeletal muscle increase the duration of cross-bridge cycling, while increases in sarcoplasmic calcium in cardiac muscle increase the number of cross-bridges mobilized. a. True b. False 6. Statement pair #1: The force of skeletal muscle contraction can be increased by recruiting either a large or small motor unit. The increase in force will be greater with recruitment of a large motor unit.
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This note was uploaded on 08/09/2008 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Spring '08 term at UC Davis.

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examfrom05 - Name _ NPB101-Sp05 MT2 Multiple Choice...

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