Explain the processes that lead to the exocytosis of neurotransmitter from a pre

Action potential arrives in synaptic terminal, and stimulates opening of voltage-regulated calcium channels. The resulting calcium influx triggers exocytosis of synaptic vesicle contents. The phospholipids of the vesicle membranes are recycled, either from fusion of vesicles then later formation of new vesicles from the same molecules; or from the kiss-and-run model, in which the vesicle phospholipids are not incorporated into the membrane at all, but remain as vesicles that can be refilled with neurotransmitter.

The action potential triggers the release of the neurotransmitter by the process of exocytosis.The action potential produces an influx of calcium ions through voltage-dependent, calcium-selective ion channels.Calcium ions then bind with the proteins found within the membranes of the synaptic vesicles, allowing the vesicles to "dock" with the presynaptic membrane resulting in the creation of a fusion pore.The membrane added by this fusion is later retrieved by endocytosis and recycled for the formation of fresh neurotransmitter-filled vesicles.
Ca+ ion is important for triggering the process of exocytosis.