RETSIPROKNOST (Latin reciprocus which — is returned, the return, mutual) — one of physiological mechanisms of coordination of activity of nerve centers providing mutual, opposite directed regulating influence on functions of bodies and fabrics.
For the first time the reciprocal relations between a muscle of heart and muscular elements of a wall of arteries were described in 1866 by I. F. Tsion; E. Goering and Breyer (J. Breuer, 1868) showed R. in work of a respiratory center; Meltzer and Kronekker (S. J. Meltzer, H. Kronecker, 1883) opened reciprocal braking at implementation of the act of swallowing, and H. E. Vvedensky (1896) established
R. at the level of a cerebral cortex. The mechanism of a reciprocal innervation of skeletal muscles was for the first time explained with I. M. Sechenov's pupil P. A. Spiro (1874) and in details analyzed by the English physiologist Ch. Sherrington (1906).
R. at the level is the most studied spinal cord (see), providing mutually opposite activity of skeletal muscles. At implementation by an organism of strictly coordinate motive acts (walking, run, swimming, hackling, swallowing, etc.) the spinal centers of antagonistic muscles are in opposite functional states (see. Movements ). E.g., excitement of group of the motor-neurons causing reduction of flexor muscles is followed by reciprocal braking of other group of motor-neurons that leads to relaxation of extensor muscles.
Direct research of processes excitement (see) and braking (see) in single nervous cells, carried out by means of microelectrodes, allowed to explain the neurophysiological mechanism P. It is shown, in particular, that the afferent nerve fibrils going from proprioceptors of skeletal muscles signal in a spinal cord about degree of their stretching and on one branch of an axon cause the excitement of motor-neurons leading to reduction of extensor muscles. The second branch of an axon of a sensory neuron through an internuncial inhibitory neuron at the same time brakes the motor-neurons providing an innervation of flexor muscles of a joint. The similar mechanism P. is described in other structures of c. N of page: thalamus, hippocampus, reticular formation, cranked bodies, cerebellum and bark of big hemispheres. So, the mechanism of change of a breath and exhalation includes R. between the inspiratory and expiratory centers. The river is characteristic of the centers of hunger and saturation, and also of pressor and depressor departments of a vasomotor center.
R.'s disturbances are most often observed at the diseases connected with poisoning with toxic drugs (e.g., strychnine) or with infectious diseases (e.g., tetanus), to-rye are followed by functional disturbances of c. N of page.
Bibliography: Beritashvili I. S. General physiology of a muscular and nervous system, t. 2, M., 1966; Granite P. Bases of regulation of movements, the lane with English, M., 1973; Sherrington H. Integrative activity of a nervous system, the lane with English, JI., 1969; Ekkls D. Brake ways of the central nervous system, the lane with English, M., 1971, bibliogr.; With at about n E. u. Ludwig of Page F. W. Die Reflexe eines der sensiblen Nerven des Herzens auf die motorischen der Blutgefasse, Arb. physiol. Anst. Lpz., Bd 1, S. 128, 1867.
Yu. A. Fadeyev.