Cells in the nervous system communicate with each other by means of such electrical signals of around a tenth of a volt that rapidly travel along the nerve processes. This substance affects receptors on the target cell, often by opening ion channels. The membrane potential is hereby altered so that the cell is stimulated or inhibited. The nervous system consists of a series of networks each comprised of nerve cells connected by synapses with different functions. New memory traces in the brain are for example created by altering the number of available ion channels in the synapses of a given network.
All cells function in a similar way.
In fact, life itself begins with a change in membrane potential. As the sperm merges with the egg cell at the instant of fertilization ion channels are activated. The resultant change in membrane potential prevents the access of other sperm cells. An immediate change in the shape of the molecule leads to either an opening or a closure of the ion channel. Alternatively a specific part of the molecule that senses changes in membrane potential can open or close the ion channel.