PERISTALTICS

From Big Medical Encyclopedia

PERISTALTICS (grech, peristaltikos covering, squeezing) — the rhythmic reductions of walls of a gullet, stomach, intestines, an ureter and other hollow bodies providing movement of their contents in the caudal direction.

The basis of the peristaltic movement is made by the wave of coordinate reduction of circular and longitudinal unstriated muscles extending along body. Before peristaltic reduction the wall relaxes a little that promotes movement of contents in the direction of a peristaltic wave. In a stomach and intestines peristaltic reductions accumulate on other types of muscular activity, in particular on rhythmic segmentoobrazny reductions. RITKHM and rate of propagation of peristaltic waves are not identical in various departments went. - kish. path.

The mechanism P. as coordinate reductions of longitudinal and circular layers of an unstriated muscle was studied on the example of P. of intestines. In 1899 Beyliss (W. M of Vau-liss) and AA. The Starling was found out that the answer of a small intestine to local irritation consists of the reduction arising above the place of irritation, and the relaxation which is observed below the stimulated area. This phenomenon was called by «the law of intestines». According to it P. of intestines consists in consecutive sokratitelny reactions of a wall of a gut on local incentives. Chyme (see), stimulating a wall of a gut, above the site of irritation causes its reduction, and below — relaxation; the chyme stimulates a new cycle of reduction of unstriated muscles in a new point of intestines, and thus food masses moves along intestines. Later, in 1902, U. Kennon showed that the mienteralny reflex which is carried out with the assistance of the nervous structures put in intermuscular (auerbakhovy) texture and a submucous (meyssnerovy) plexus (is the cornerstone of «the law of intestines» see. Intestines ). It was proved in experiences with suppression of a reflex by influence by cocaine or nicotine on a serous cover or novocainization of a submucosa of intestines therefore there was a disturbance of a strict orientation of the movement of waves of reduction: they began to extend both in caudal, and in the oral direction. The movement of peristaltic waves only in the caudal direction is explained, first, by existence of a gradient of frequency of spontaneous rhythmic reductions of intestines (the largest frequency of rhythmic reductions the duodenum, the smallest — ileal possesses) and, secondly, as showed P. G. The rich man (1974), maintenance of polarity (orientation) of distribution of waves pacemakers of a rhythm of intestinal reductions (see. Pacemaker ). One of such pacemakers is located in a duodenum in the place of a confluence bilious and small pancreatic channels, another — in an ileal gut.

The regulating impact on P. is exerted by century of N of page: sympathetic fibers preferential brake, parasympathetic preferential excite peristaltic activity. Respectively adrenaline and noradrenaline brake P., and acetylcholine excites P., renders two-phase effect on P. P. are influenced by also many biologically active agents — serotonin, a histamine, substance P, bradikinin (excite peristaltic activity), Pituitrinum, oxytocin (brake P.). In various departments of c. the N of page (a hypothalamus, an amygdaloid complex, limbic area) are available the centers, to-rye can excite or brake P. V of regulation of peristaltic activity also also the cerebral cortex that was confirmed on animals with method of conditioned reflexes and a wedge, observations (under the influence of fear, concern, pain P.'s character changed) participates. In a small intestine under the influence of laxatives, enemas * asphyxia the so-called prompt peristaltics (a peristaltic push) which is quickly advancing contents of a gut rdzvivatsya.

The antiperistalsis, i.e. the movement of a wave of reductions in the opposite direction is sometimes observed. Normal in a small intestine and a stomach the antiperistalsis is absent, but is fiziol, property of a large intestine, providing a delay of contents in it and the best digestion of food. The antiperistalsis of a small intestine and stomach arises owing to pathology of appropriate authority (commissure, pressure of a tumor and other reasons), and also at vomiting.



Bibliography: Klimov P. K. Functional interrelations in the alimentary system, JI., 1976; Physiology of digestion, under the editorship of A. V. Solovyov, JI., 1974; Physiology of digestion, under the editorship of V. N. Chernigovsky, page 474, JI., 1974; In and at 1 i s s W. M. a. S t and of 1 i n g E. H. The movements and the innervation of the large intestine, J. Physiol. (Lond.), v. 26, p. 107, 1901; GannonW. B. Peristalsis, segmentation and the myenteric reflex, Amer. J. Physiol., v. 30, p. 114, 1912 — 1913.


P. S. Orlov.

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