TEST 3 A - Question 1 Your answer is CORRECT. Thin...

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Question 1 Your answer is CORRECT. Thin filaments in skeletal muscle are composed of: a) actin b) myosin c) troponin and tropomyosin d) both [a] and [c] e) all of these answers Question 2 Your answer is CORRECT. The functional unit of skeletal muscle is the: a) smallest contractile component of a muscle fiber b) area between two Z lines c) sarcomere d) all of these answers e) none of these answers Question 3 Your answer is CORRECT. In an isotonic contraction, the muscle: a) changes in length and moves the load b) does not change in length but increases tension c) never converts pyruvate to lactic acid d) rapidly resynthesizes creatine phosphate and ATP Question 4 Your answer is CORRECT. During a cross-bridge cycle in skeletal muscle, the: a) crossbridge is energized as myosin ATPase activity hydrolyzes ATP. b) myosin crossbridge is able to bind with an actin molecule when Ca2+ pulls the troponin-tropomyosin complex aside. c) linkage between actin and the myosin crossbridge is broken at the end of the crossbridge cycle as Mg2+ binds to the crossbridge d) both [a] and [b] e) all of these answers. Question 5 Your answer is CORRECT. Which is not characteristic of smooth muscle? a) it is under involuntary control b) it lacks troponin c) its contraction is initiated neurogenically d) it is found in the walls of hollow tube-like organs e) it is innervated by the ANS
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Question 6 Your answer is INCORRECT. In twitch summation: a) The muscle fiber is stimulated again before the action potential has returned to resting potential. b) The muscle fiber is stimulated again before the filaments have completely returned to their resting position. c) Stronger muscle contractions occur but stronger action potentials do not occur. d) Both [b] and [c] above e) All of these answers Question 7 Your answer is CORRECT. When a muscle fiber contracts, the I bands and H zones diminish in length, whereas the A bands move closer together but do not diminish in length. a) True b) False Question 8 Your answer is CORRECT. Calcium ions bind troponin allowing the myosin-binding site on actin to be made available in smooth muscle contraction. a) True b) False Question 9 Your answer is CORRECT. The T tubule is responsible for storing Ca2+ for muscle contractions. a) True b) False Question 10 Your answer is CORRECT. Because there are no sarcomeres, smooth muscles do not possess thick and thin filaments. a) True b) False Question 11 Your answer is CORRECT. Blood returning from the systemic circulation: a) enters the right atrium. b) enters the left atrium c) is poorly oxygenated. d) both [a] and [c] above e) both [b] and [c] above Question 12 Your answer is INCORRECT.
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The plateau of the cardiac action potential results from the opening of voltage-gated slow _____ channels in the plasma membrane of the cardiac cell. a) sodium
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TEST 3 A - Question 1 Your answer is CORRECT. Thin...

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