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Action Potentials and Muscle Contraction

Muscle contraction is controlled by motor neurons that release that neurotransmitter a acetylcholine at neuromuscular junctions. Acetylcholine the diffuse across the narrow synaptic cleft, and binds to acetylcholine receptors on the membrane of the muscle cell. This results in the opening of ion channels within the receptor molecules, in such a way that a depolarizing, synaptic ion current can flow. This current triggers an all or nothing response in the form of an action potential across the plasma membrane of the muscle cell.

 

The action potential moves out in all directions from the neuromuscular junction, resulting in stimulation of the entire muscle fiber. Within a few milliseconds, the contractile mechanism responds and fiber contractile.

 



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