2.2 Synaptic Communication

The neural signal is not complete at the axon terminal. When the action potential arrives at the axon terminal it triggers a series of events that lead to the activation of synaptic vesicles. The vesicles release of their neurotransmitters into the synapse. The neurotransmitters travel across the synapse where they bind with receptors on the post-synaptic neuron. This is illustrated in Figure 2.3

The post-synaptic receptors on the receiving neuron can produce excitatory or inhibitory post-synaptic potentials which are transmitted to the cell body of that neuron and the process begins again in that neuron.

The neurotransmitters that have completed their actions and the excess neurotransmitter left in the synapse must be deactivated. This is done in one of several ways. In some cases, the neurotransmitter is broken down by enzymes. Another ways is the process of re-uptake, where the neurotransmitter is recaptured into the neuron that delivered it at a special binding site. It is then recycled to be used again. Other neurotransmitters diffuse away from the synapse. Yet others are taken up by neighboring glial cells and stored for later export to axon terminals.