In this chapter, we have discussed the cells of the nervous system (glial cells and neurons) and have looked at the components that make up a neuron in order for it to function.
Communication within the neuron happens through electrical impulses, which are triggered by neurotransmitters received from other presynaptic neurons. The resulting action potential (a change in cell voltage, because of a rapid movement of ions in and out of the cell) fires from the axon hillock, down the axon to the synaptic button.
From the synaptic button, it triggers the release of neurotransmitters from the presynaptic neuron, which diffuse across the synaptic cleft and bind to receptors on the postsynaptic neuron (communication between neurons). Most neurotransmitters’ effects are terminated by the reuptake of excess neurotransmitter from the synaptic cleft back into the presynaptic neuron. Other neurotransmitters’ activity is terminated when enzymes that bind to them break them down.
Neurotransmitters work in circuits and systems, made up of collections of neurons, and these interact to produce cognition, behaviour and experience. Drugs can influence the functioning of neurons because they mimic neurotransmitter structures. Drugs can facilitate the effects of neurotransmitters on the postsynaptic neuron (agonist) or they can inhibit the effects of neurotransmitters on the postsynaptic neuron (antagonist). Drugs can affect any of the stages involved in synaptic transmission.