PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Tropin
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ATP
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Potassium
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Myosin
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Detailed explanation-1: -The calcium ions released from endoplasmic reticulum72) bind to the calcium-binding subunit of troponin (troponin-C (TnC), ∼18 kDa), and the inhibition by troponin is neutralized to trigger muscle contraction.
Detailed explanation-2: -Troponin plays an important role during excitation-contraction coupling. During excitation, calcium ions bind to TnC; it interacts with tropomyosin to unblock active sites between the myosin filament and actin allowing cross-bridge cycling and thus contraction of the myofibrils that constitute the systole.
Detailed explanation-3: -Troponin is shown in red (subunits not distinguished). Upon binding calcium, troponin moves tropomyosin away from the myosin-binding sites on actin (bottom), effectively unblocking it.