Each transmitter is chemically unique although a number of transmitters are actually manufactured from other transmitters. Neurotransmitters are manufactured in the neuron cell body and transported down the axon contained in small containers called vesicles. The vesicles are moved all the way down the axon to the presynaptic terminals using a process called anterograde transport . Interestingly enough, the axons are not just hollow tubes but rather contain a large number of smaller tubules and microtubules that play a major role in the life of the cell. The result is that the interior volume of the axon is constantly busy.
Action potentials form only a part of their activities.
Once the vesicles reach the presynaptic terminals, they are held there. This process is called exocytosis . In the cleft, the chemicals attach to the cell membrane of the next neuron and alter the potential inside it. The neurotransmitters are rapidly deactivated and are then reabsorbed into the vesicles, a process called pinocytosis . One in the cell body, the chemical components are used to manufacture new transmitters.