PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The actual muscle contraction is caused by ____
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the thick myofilament pulling the thin myofilament to the M line
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the thick filament pulling the tropomyosin to the M line
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calcium binding to troponin
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calcium returning to the terminal cisternae
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Explanation:
Detailed explanation-1: -During muscle contraction, the heads of myosin myofilaments quickly bind and release in a ratcheting fashion, pulling themselves along the actin myofilament.
Detailed explanation-2: -Thin filaments are pulled by the thick filaments toward the center of the sarcomere until the Z discs approach the thick filaments. The zone of overlap, in which thin filaments and thick filaments occupy the same area, increases as the thin filaments move inward.
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