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 releaseEdit

  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