The neuromuscular junction is a well-studied example of a chemical synapse. which of the following statements describes a critical event that occurs at the neuromuscular junction? a) acetylcholine is released by axon terminals of the motor neuron. b) when the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal. c) acetylcholine binds to its receptor in the junctional folds of the sarcolemma. its receptor is linked to a g protein. d) acetylcholine is released and moves across the synaptic cleft bound to a transport protein.