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