Synapse
Contact zone between nerve cells or between nerve cells and other cells of the body at which chemical vectors (neurotransmitters) are released from the vesicles of the presynaptic nerves. Via the neurotransmitters an excitation-producing or -inhibiting signal is transmitted to the postsynaptic cell.
The gap between presynaptic and postsynaptic membranes has a rather constant width of 16 to 30 nanometres, which is about 0.2 millionths of a millimetre or 1000 times thinner than a sheet of paper. The postsynaptic membrane contains the receptors that react like keyholes to the neurotransmitters as their keys and post-synaptically build up a new bioelectrical signal.