The presynaptic terminal is the part of the neuron that releases neurotransmitters. It contains synaptic vesicles filled with neurotransmitters. When an action potential arrives at the presynaptic terminal, it triggers the opening of voltage-gated calcium channels. The influx of calcium ions causes the synaptic vesicles to fuse with the presynaptic membrane and release their contents into the synaptic cleft through a process called exocytosis.
