PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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What has to happen to stop the muscle contraction and cause the muscle to relax? (Select all that apply)
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Acetylcholinesterase enzymes must break down acetylcholine in synaptic cleft
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Myosin heads release actin filament
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Calcium must be pumped back into sarcoplasmic reticulum
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Tropomyosin changes shape to cover binding sites
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Explanation:
Detailed explanation-1: -This decrease in intracellular Ca concentration returns the troponin complex to its inhibiting position on the active site of actin, ending contraction as the actin filaments return to their initial position, relaxing the muscle.
Detailed explanation-2: -Tropomyosin blocks myosin binding sites on actin molecules, preventing cross-bridge formation, which prevents contraction in a muscle without nervous input. The protein complex troponin binds to tropomyosin, helping to position it on the actin molecule.
There is 1 question to complete.