Explain the processes that lead to the exocytosis of neurotransmitter from a presynaptic cell. which components are recycled? which ion is important in triggering exocytosis?

1)In exocytosis: The neurotransmitter is produced, vesicles are formed around the neurotransmitters to be released and they fuse with the outer membrane of the presynaptic cell.  Then, their contents (neurotransmitters) are secreted into the synaptic cleft.

2) the compounds recycled: Vesicles.
The membranes formed from old vesicles become part of the presynaptic membrane and new vesicles surge from that area of the membrane. These new vesicles are refilled with more neurotransmitters.

3) Calcium ions.
Action potentials open calcium channels that are in the membrane of the presynaptic cell, which causes the Ca+ ions to move to inside the cell . Calcium ions trigger the release of neurotransmitter from the vesicles into the synaptic cleft.