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Human Phys Exam 3 F07 - 1 Question 1 Question 4 Your answer...

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1 Question 1 Your answer is CORRECT. Thick filaments in skeletal muscle are composed of: a) actin b) troponin and tropomyosin c) myosin d) actin, troponin, and tropomyosin e) all of these answers Question 2 Your answer is CORRECT. In an isometric 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 3 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 4 Your answer is INCORRECT. Summation: a) Results from increases in cytosolic calcium levels. b) Pumping of calcium into the sarcoplasmic reticulum. c) Can be enhanced by allowing a cell to completely relax. d) Rarely results in tetanus. e) All of these answers. Question 5 Your answer is CORRECT. Smooth muscle is characterized by all of the following except: a) it lacks troponin b) it is multinucleated c) typically arranged in syncytia surrounding the hollow organs d) there are noncontractile intermediate filaments that attach to dense bodies within the cell e) it is under involuntary control Question 6 Your answer is CORRECT. Which of the following statements regarding skeletal muscle is not true: a) ATP in muscles cells is required for cross- bridges between actin and myosin. b) Calcium binds troponin allowing the myosin- binding site on actin to be made available. c) Calcium is stored in the sarcoplasmic reticulum. d) Skeletal muscles lack mitochondria e) None of these Question 7 Your answer is CORRECT. The T tubule is responsible for storing Ca2+ for muscle contractions. 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
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2 Question 9 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 10 Your answer is INCORRECT. The rapid rising phase of the cardiac contractile cells action potential results from the opening of voltage-gated _____ channels in the plasma membrane of the cardiac cell. a) sodium b) potassium c) calcium d) chloride e) magnesium Question 11 Your answer is CORRECT. The QRS complex represents: a) depolarization of the atria. b) depolarization of the ventricles.
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