Acetylcholine receptors function as ligand-gated ion channels. Depolarization overshoot and repolarization. 2 A When Action Potential Reaches The Axon Terminal It Triggers The Download Scientific Diagram An action potential reaches the axon terminal causing voltage-gated Ca² Calcium ions enter the axon terminal leading to the release of acetylcholine via exocytosis. . What causes the inside of the membrane to reverse charge and begin the action potential. As calcium flows into the terminal the neuron releases neurotransmitters into the synaptic cleft for 1-2 milliseconds. Neurotransmitter molecules are released from the axon terminal and bind to receptors on the postsynaptic neuron causing either an inhibitory hyperpolarization or an excitatory depolarization. Voltage-gated CA2- channels. When an action potential reaches the axon terminal the depolarization causes voltage-dependent calcium gates to open. It consists of fou...