The modern theory of cell-to-cell transmission is commonly based on idea about chemical intermediaries (transmitter agents) securing transmission between two neurons in the synaptic cleft or between the motor neuron and muscle fiber in the neuro-muscular junction. About ten millions of transmitter molecules are releasing simultaneously under the influence of the nerve impulse and then the chemical reactions are taking place. In order to describe the major events in synapse the simplified scheme is used. Kinetic equations corresponding to the scheme of biochemical reaction in synaptic cleft have non-linear form. Using some special approximations it is possible to investigate the main characteristics of such a system. Considering the synaptic transmission as the process which is isomorphic to the critical phenomena in bicorrelation function of the density ( concentration) fluctuations and determine the size of the activation zone and other critical parameters.
