VISCERAL REFLEXES

From Big Medical Encyclopedia

VISCERAL REFLEXES (Latin viscera of an interior) — reflexes which begin or come to an end on internals.

Distinguish reflexes viscerovisceral (from one internal body on another), vistsero-somatic (from internals on skeletal muscles) and somato-visceral (e.g., from skin receptive fields on internals). On V. N. Chernigovsky's classification, rubles are subdivided by V., besides, on system and interfaced. The reflexes covering bodies of a certain system, napr, reaction of all digestive tract at irritation of a mucous membrane of a stomach belong to system. Reflexes in which excitement as a result of irradiation covers bodies of various systems belong to interfaced.

Threshold irritations for system reflexes are lower, than for interfaced. E.g., increase in pressure in a bladder at first causes reflex changes of sphincters of an urethra and a bubble and only then changes the level of the general blood pressure. The sensitive terminations of any body can become a reflexogenic zone B. of river. Centrifugal part B. of river is made by sympathetic or parasympathetic nerves (see. Autonomic nervous system ). V.'s short circuit by the river happens at the different levels of a nervous system. Some V. ruble become isolated in a nearby ganglion of the autonomic nervous system, napr, reflexes on motility of intestines at irritation of one of its sites. The reflexes which are becoming isolated in a spinal cord are called spinal V. of river, napr, increase in a blood-groove in one kidney at its restriction in another. At the spinal level reflexes from the somatic afferent terminations on internals and blood vessels can also become isolated.

In a myelencephalon numerous reflex arcs of systems of digestion, breath, blood circulation (bulbar reflexes) become isolated.

In the middle of the last century the German physiologist F. L. Holtz opened the bulbar reflex which is expressed in braking of cordial activity at stretching of walls of a stomach, intestines or mesentery.

Some V. ruble become isolated in overlying departments of c. N of page, especially in a hypothalamus which participates in regulation of various visceral functions. Selective sensitivity of hypothalamic neurons to changes of temperature, osmotic pressure of a blood plasma, content of glucose in it etc. allows this education to participate in special type B. of the ruble providing constancy of internal environment of an organism. The responses arising at the same time can include a humoral link of regulation (see. Neurohumoral regulation ).

Participation of subcrustal educations and a cerebral cortex in V. of river allows to speak about the interoceptive analyzer (see. Interoception ) as sets of the nervous structures participating in the analysis of the nervous signals going from internals and exerting powerful impact on activity of internals (see. Limbic system ). The majority of visceral functions is subject to uslovnoreflektorny regulation (see. Conditioned reflex ). It must be kept in mind what an effector in similar reflexes can be as muscular (a myocardium or unstriated muscles of sphincters), and ferruterous fabric. Some V. of river are followed by change of level of exchange processes of internals.

Century of river can matter in clinic. E.g., at overflow of a stomach, especially people, inclined to completeness, can have pains in heart because of a reflex spasm of coronary vessels, change of pulse and blood pressure.


Bibliography: Babkin P. S. Reflexes and their clinical value, M., 1973; Bulygin I. A. Switching and receptor function vegetative gangliyev, Minsk, 1964, bibliogr.; Kulayev B. S. Reflexogenic zone of heart and self-control of blood circulation, L., 1972, bibliogr.; The p e r N and about in with to and y V. N. Interoretseptora, M., 1960, bibliogr.; BenzingerT. H. Heat regulation, homeostasis of central temperature in man, Physiol. Rev., v. 49, p. 671, 1963, bibliogr.; K o r n e r P. I. Integrative neural cardiovascular control, ibid., v. 51, p. 312, 1971, bibliogr.; Kuntz A. The autonomic nervous system, Philadelphia, 1945, bibliogr.

I. M. Rodionov.

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