Presynaptic terminal

The Presynaptic terminal is the specialized terminus of certain axon fibers.

It is the site for neurotransmitter release across a synapse and also where the action potential terminates in adults.

Neurotransmitter release

 * 1) Action potential depolarizes cell membrane
 * 2) Voltage-gated calcium ion channels open and allow Ca+2 into the presynaptic terminal
 * 3) Calcium is a participant in an intracellular cascade which results in the activation of SNARE proteins
 * 4) Vesicles with neurotransmitters detach from the Golgi complex and are guided by a myriad of intracellular proteins
 * 5) Vesicles dock with the active zone, and fuse with the plasma membrane, exocytosing their contents within 1 millisecond - neurotransmitters - into the synaptic cleft
 * 6) Vesicles break off from the active zone in 5-20 milliseconds, returning back to the Golgi complex