where is acetylcholine released from to stimulate muscle contraction
Acetylcholine When a motor neuron generates an action potential, it travels rapidly along the nerve until it reaches the neuromuscular junction, where it initiates an electrochemical process that causes acetylcholine to be released into the space between the presynaptic terminal and the muscle fiber. The acetylcholine molecules then bind to nicotinic ion-channel receptors on the muscle cell membrane, causing the ion channels to open. Calcium ions then flow into the muscle cell, initiating a sequence of steps that finally produce muscle contraction.