VESTIBULAR REACTIONS

From Big Medical Encyclopedia

VESTIBULAR REACTIONS — the reactions of an organism arising in response to adequate (inertial and gravitational forces) and not adequate (temperature, electric current) of irritation of a vestibular analyzer.

Thanks to existence of two systems of receptor formations of a vestibular analyzer — otolitovy and kupulo-endolymphatic (semicircular channels of a labyrinth of an inner ear) — there is a differentiated perception of forces generating rectilinear including the gravity, and curvilinear accelerations, so-called labyrinth reactions are carried out. Limit of sensibilitys of receptors of otolitovy system are estimated in 0,001 — 0,03 g, receptors of semicircular channels — within 0,12 — 2 hails/sec. 2 lasting influence of 0,15 sec. The exception is represented by Coriolis's accelerations (see. Coriolis acceleration ), which, despite their classification as rectilinear accelerations, have low thresholds of stimulation of vestibuloretseptor: 0,006 — 0,06 m/s 2 . There is a basis to believe that in process of increase of power of irritation differentiation between two receptor systems of a labyrinth becomes less natural. Extensive nervous bonds vestibular analyzer (see) with cortical and subcrustal representations of different types of sensitivity, and also with the centers of the autonomic nervous system provide variety of manifestations of vestibular reactions. Allocate 3 types of vestibular reactions: somatic, touch and vegetative. The first are the main, evolutionarily fixed and determining the main function of a vestibular analyzer by saving the space provision. Spinal reflexes of cross-striped muscles, reflexes of more high levels of c concern to them. the N of page directed to the preservations of a tone of muscles and balances normalizing a pose and providing coordination of movements. Carry to somatic reflexes also vestibular nystagmus (see).

Touch (cortical) reactions arise at a certain intensity of irritations and are expressed by feeling of dizziness, various illusory feelings of own space situation or surrounding objects relatively each other. They korrigirutsya by ideas of an uslovnoreflektorny visual vertical.

Vestibulo-vegetativnye reactions represent a complex of reflexes, various on the functional manifestations, in which implementation the autonomic nervous system takes part.

In normal conditions vestibulo-vegetative reactions provide the level of exchange processes necessary at present in muscular system. The regulating impacts of a vestibular analyzer on a condition of internal environment of an organism are proved (in particular, on system of coagulability of blood).

However at long influence of vestibular irritations, especially sign-variable accelerations, failure of adaptable mechanisms of the autonomic nervous system with emergence of pathological reactions in the form of a symptom complex of a disease of movement (kinetoza, a motion sickness, sea, air, space, transport diseases) is possible. Manifestations: the condition of discomfort, disturbance of haemo circulation, is preferential in vessels of a brain (early manifestations), disturbance of cordial activity (reduction of a stroke output of heart), breath, emergence of perspiration, blanching, nausea, vomiting, up to a collapse (see. Vestibular symptom complex , Motion desease ).

The pathogenetic basis of a disease of movement at sign-variable accelerations is made by disturbances of functional relationship of the structures forming a vestibular analyzer with other formations of c. N of page, including those which are responsible for regulation of vegetative functions.


Bibliography: Grigoriev Yu. G., Farber Yu. V. and Volokhovan. A. Vestibular reactions (Methods of a research and influence of various environmental factors), M., 1970, bibliogr.; M about of e of N d the island and M. R's h. Reflex interaction of locomotory and visceral systems, L., 1957, bibliogr.; Razumev in A. N. and A. A Thorns. Nervous mechanisms of vestibular reactions, M., 1969, bibliogr.; X and l about in K. L. Function of an organ of equilibrium and disease of movement, L., 1969, bibliogr.

M. D. Yemelyanov.

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