Answer
Acetylcholine receptors are on membrane of the motor end plate. Acetylcholine released by exocytosis into the synaptic cleft is taken up by ( or binds to) these receptors.
Work Step by Step
The binding of ACH to acetylcholine receptors results in opening of sodium (Na+) ion channels. The entry of Na++ ions down the the sodium eletrochemical gradient makes the inside of the muscle fiber more positive and this triggers a muscle action potential (AP).
