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Chapter 5. Excitable Tissue: Muscle
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The action potential of skeletal muscle
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A. has a prolonged plateau phase.
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B. spreads inward to all parts of the muscle via the T tubules.
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C. causes the immediate uptake of Ca2+ into the lateral sacs of the sarcoplasmic reticulum.
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D. is longer than the action potential of cardiac muscle.
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E. is not essential for contraction.
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The functions of tropomyosin in skeletal muscle include
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A. sliding on actin to produce shortening.
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B. releasing Ca2+ after initiation of contraction.
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C. binding to myosin during contraction.
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D. acting as a “relaxing protein” at rest by covering up the sites where myosin binds to actin.
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E. generating ATP, which it passes to the contractile mechanism.
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The cross-bridges of the sarcomere in skeletal muscle are made up of
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The contractile response in skeletal muscle
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A. starts after the action potential is over.
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B. does not last as long as the action potential.
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C. produces more tension when the muscle contracts isometrically than when the muscle contracts isotonically.
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D. produces more work when the muscle contracts isometrically than when the muscle contracts isotonically.
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E. decreases in magnitude with repeated stimulation.
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A. are absent in cardiac muscle.
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B. are present but of little functional importance in cardiac muscle.
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C. are present and provide the pathway for rapid spread of excitation from one cardiac muscle fiber to another.
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D. are absent in smooth muscle.
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E. connect the sarcotubular system to individual skeletal muscle cells.