PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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When does myosin stop its bind, pull, release, bind, pull, release ____ cycle?
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When the calcium gets removed from the cytoplasm.
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When the myosin gets tired.
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When new ATP is produced.
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When more calcium gets released into the cytoplasm.
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Explanation:
Detailed explanation-1: -In striated muscle, calcium causes a shift in the position of the troponin complex on actin filaments, which exposes myosin-binding sites (Fig. 2A). Myosin bound by ADP and inorganic phosphate (Pi) can then form cross-bridges with actin, and the release of ADP and Pi produces the power stroke that drives contraction.
Detailed explanation-2: -Stimulation of the muscle fibre, causes a wave of depolarisation to pass down the t-tubule, and the SR to release calcium ions into the sarcoplasm. Calcium is pumped back up into the SR to lower calcium ion concentration in the sarcoplasm, to relax the muscle (turn off contraction).
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