PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A neurotransmitter called Acetylcholine (ACh)
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Calcium ions
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Sodium ions
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An action potential
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Detailed explanation-1: -When an action potential reaches a neuromuscular junction, it causes acetylcholine to be released into this synapse. The acetylcholine binds to the nicotinic receptors concentrated on the motor end plate, a specialized area of the muscle fibre’s post-synaptic membrane.
Detailed explanation-2: -When the nerve impulse from a motor neuron arrives at the tip of its axon, acetylcholine molecules stored there in vesicles are released into the synaptic gap. Some of these molecules then bind to nicotinic receptors: large proteins embedded in the membrane of the muscle fibre.
Detailed explanation-3: -(A) Neurotransmitter (acetylcholine, ACh) released from nerve endings binds to receptors (AChRs) on the muscle surface. The ensuing depolarization causes sodium channels to open, which elicits an action potential that propagates along the cell.