A synapse is a place of contact of two cell membranes, ensuring the transfer of excitation from the nerve endings in excitable structures (glands, muscles, neurons). Depending on the structure of synapses divided into neurosecretory, neuromuscular, Mineralnye. Synapse consists of 2 membranes: presynaptic, which is part of the nerve endings, and postsynaptic owned excitable structure.
The transfer of excitation in the synapse is carried out by means of specific chemical mediators (see). The most common mediators are norepinephrine and acetylcholine. The structure of the synapse and the transmission mechanism of excitation determine its physiological properties: 1) the unilateral conduct of excitation, connected with allocation of a mediator only on presynaptic membrane; 2) synaptic transmission delay of excitation, connected with slow selection of the mediator and his impact on the postsynaptic membrane, it can grow with multiple passing of excitation (summation effects and facilitate); 3) a synapse has low lability and mild fatigue; 4) the chemical mechanism of excitation transfer in the synapse leads to high sensitivity of the synapse to hormones, drugs and poisons.