Describe the process of synaptic transmission with regard to action potentials

the action potential arrives at the terminal of the axon. The arrival of the action potential will cause voltage gated calcium ions to open allowing the calcium ions to rush into the axon terminal. The arrival of the calcium ions allow synaptic vesicles to fuse with the axon terminal membrane, releasing neurotransmitter into the synaptic cleft. The neurotransmitter (most common one being acetylcholine) diffuses across the synaptic cleft and bind with the ligand-gated ion channel. This can cause inhibitory or excitatory effects.