ANATOMY

Detailed explanation-1: -(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.

Detailed explanation-2: -Acetylcholine Opens Ion Channels on Postsynaptic Membranes The voltage-gated sodium channels also line the subneural clefts. Each acetylcholine receptor is a protein complex that has a total molecular weight of approximately 275, 000.

Detailed explanation-3: -For example, when acetylcholine is released at the synapse between a nerve and muscle (called the neuromuscular junction) by a presynaptic neuron, it causes postsynaptic Na+ channels to open.

Detailed explanation-4: -The release of acetylcholine occurs when an action potential is relayed and reaches the axon terminus in which depolarization causes voltage-gated calcium channels to open and conduct an influx of calcium, which will allow the vesicles containing acetylcholine for release into the synaptic cleft.

Detailed explanation-5: -The membrane depolarization at the synaptic cleft triggers nearby voltage-gated sodium channels to open.