(N/A) The process of neurotransmitter release occurs at the synapse through the following steps:
$1$. An action potential travels down the axon to the axon terminal.
$2$. The depolarization of the membrane at the axon terminal opens voltage-gated $Ca^{2+}$ channels.
$3$. $Ca^{2+}$ ions flow into the synaptic knob,triggering the fusion of synaptic vesicles containing neurotransmitters with the presynaptic membrane.
$4$. Neurotransmitters are released into the synaptic cleft via exocytosis.
$5$. These neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane,initiating a new action potential or inhibitory response.