PHYSIOLOGY
SLIDING FILAMENT MODEL
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Identify what occurs first during Phase 1 of an Action Potential of the muscular system?
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Action Potential arrives at axon terminal of motor neuron
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Calcium ion channels open and Calcium enters axon terminal
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Calcium causes Acetylcholine (neurotransmitter) to be released
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Action Potential travels across the entire sarcolemma
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Explanation:
Detailed explanation-1: -When an action potential, or nerve impulse, arrives at the axon terminal, it activates voltage-gated calcium channels in the cell membrane.
Detailed explanation-2: -In other words, the muscle fiber action potential always precedes the increase in intracellular Ca2+, which always precedes muscle contraction. One single action potential leading to an increased intracellular Ca2+ from sarcoplasmic reticulum release produces a single muscle contraction known as a twitch.
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