PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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What happens right after the muscle depolarizes?
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muscle depolarizes
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nerve depolarizes
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vesicles dump acetylcholine into the synpse
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muscle contracts
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everything resets, ready to contract again
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Explanation:
Detailed explanation-1: -Activation of the nAChR leads to an influx of cations (sodium and calcium) that causes depolarization of the muscle cell membrane. This depolarization in turn activates a high density of voltage-gated sodium channels on the muscle membrane, eliciting an action potential.
Detailed explanation-2: -Depolarization of the sarcolemma leads to opening of voltage-gated Ca2+ channels and influx of Ca2+ from the extracellular space. This Ca2+ pulse can also trigger the release of intracellular Ca2+ from the sarcoplasmic reticulum (Ca2+-induced Ca2+ release, CICR).
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