peristalsis

peristalsis:

see digestive systemdigestive system,
in the animal kingdom, a group of organs functioning in digestion and assimilation of food and elimination of wastes. Virtually all animals have a digestive system. In the vertebrates (phylum Chordata, subphylum Vertebrata) the digestive system is very complex.
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Peristalsis

a wavelike contraction that propels the contents of tubular organs, for example, the intestine, stomach, and ureters, caudally in animals or in a downward direction in man. Peristalsis is the result of many coordinated contractions of the longitudinal and transverse muscles in the walls of a tubular organ. A single peristaltic wave takes the form of a circular constriction around the lumen that moves along the length of the organ. The walls of the organ are always slightly relaxed before the arrival of the constriction, so that the wave appears to push the contents in the direction in which it travels. Peristaltic waves follow each other continuously at a fixed rhythm and rate. In man, for example, the peristaltic rhythm of the stomach is 3 waves/min, with each wave moving at the rate of 0.5 cm/sec; intestinal peristalsis occurs at the rate of 6 waves/min.

Peristalsis is conditioned by the ability of smooth muscles to contract automatically and by the functioning of nerve plexuses in the muscles. The autonomic nervous system and humoral factors regulate peristalsis. Furthermore, the central nervous system, including the cerebral cortex, may participate in the regulation of peristalsis. This was experimentally demonstrated in animals by inducing changes in peristaltic patterns using conditioned reflexes. Observations on humans show that anger and pain inhibit peristalsis, whereas fear sometimes intensifies it; these observations are taken as further evidence that the cortex may have a role in peristaltic control. However, peristalsis is well indicated in isolated parts of the intestine. Medications and the physical and chemical properties of foods also affect peristalsis.

REFERENCES

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peristalsis

[‚per·ə′stäl·səs] (physiology) The rhythmic progressive wave of muscular contraction in tubes, such as the intestine, provided with both longitudinal and transverse muscular fibers.

peristalsis

Physiol the succession of waves of involuntary muscular contraction of various bodily tubes, esp of the alimentary tract, where it effects transport of food and waste products

Peristalsis

peristalsis

[per″ĭ-stal´sis] the wormlike movement by which the alimentary canal or other tubular organs with both longitudinal and circular muscle fibers propel their contents, consisting of a wave of contraction passing along the tube. adj., adj peristal´tic.
When food is swallowed, it passes into the esophagus. Muscular contractions in the wall of the esophagus work the food downward, pushing it into the stomach. Here peristaltic contractions not only move the food in small amounts into the intestine but also aid in the disintegration of the food and help mix it with gastric juice. Peristalsis forces the food into and through the intestine for further digestion until the food waste finally reaches the rectum, from which it is periodically discharged from the body. The waves of peristalsis are irregular; they are stronger at some times than at others. They are also weaker in some people, notably the elderly.
Although the normal peristaltic wave is downward, it is sometimes reversed. Reverse peristaltic action may be triggered by mild digestive upsets or more serious disorders, such as an obstruction in the stomach or intestines.

per·i·stal·sis

(per'i-stal'sis), The movement of the intestine or other tubular structure, characterized by waves of alternate circular contraction and relaxation of the tube by which the contents are propelled onward. Synonym(s): vermicular movement [peri- + G. stalsis, constriction]

peristalsis

(pĕr′ĭ-stôl′sĭs, -stăl′-)n. pl. peristal·ses (-sēz) The wavelike muscular contractions of the digestive tract or other tubular structures by which contents are forced onward toward the opening.

per′i·stal′tic (-stôl′tĭk, -stăl′-) adj.per′i·stal′ti·cal·ly adv.

per·i·stal·sis

(per'i-stal'sis) The movement of the intestine or other tubular structure, characterized by waves of alternate circular contraction and relaxation of the tube by which the contents are propelled onward.
Synonym(s): vermicular movement. [peri- + G. stalsis, constriction]

peristalsis

A coordinated succession of contractions and relaxations of the muscular wall of a tubular structure, such as the OESOPHAGUS, small intestine or the URETER, producing a wave-like pattern whose effect is to move the contents along.

peristalsis

the alternate contraction and relaxation of circular and longitudinal muscle which produces waves that pass along the intestine (and other tubular systems) of animals, moving the tube contents in one direction.

Peristalsis

A sequence of muscle contractions that progressively squeeze one small section of the digestive tract and then the next to push food along the tract, something like pushing toothpaste out of its tube.Mentioned in: Achalasia, Colonic Irrigation, Diffuse Esophageal Spasm, Esophageal Disorders, Heartburn, Intestinal Obstructions, Intestinal Polyps, Irritable Bowel Syndrome, Vagotomy

peristalsis

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peristalsis:

Peristalsis

REFERENCES

peristalsis

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Peristalsis

peristalsis

per·i·stal·sis

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Synonyms for peristalsis

noun the process of wavelike muscle contractions of the alimentary tract that moves food along

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