peristalsis


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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
References in periodicals archive ?
Smooth muscles in the walls of the ureters send the urine in small spurts into the bladder, in a process called peristalsis.
The indicators such as duration of operation, intraoperative blood loss, time to recovery of peristalsis and pain score in the observation group were superior to those of the control group, and the difference had statistical significance (P<0.
6] Physiologically, urine flowing from the ducts of Bellini passes under active peristalsis from the minor calyces into the major calyces and hence the renal pelvis that contracts at a rate dependent on diuresis transport of urine into the upper ureter.
Peristalsis is very sensitive to salt and water imbalance in the intestinal tract.
On fluoroscopy, the lower two-thirds of the esophagus does not have peristalsis and the terminal part has a bird beak appearance.
However, the PUF was brittle material and was easily crushed into many pieces by colonic peristalsis.
Peristalsis is the involuntary muscular contraction that moves digested food matter through the intestines so it can be eliminated.
Achalasia is a condition in which there is loss of peristalsis of the smooth muscle of the esophagus, and failure of relaxation of the lower esophageal sphincter (LES).
1B) demonstrated a megaoesophagus, with irregular and abnormal peristalsis in the proximal oesophagus.
The 11 papers consider such topics as the development of the immersed finite element method, a regularization method for the numerical solution of doubly-periodic Stokes flow, motions of filaments with planar and helical bending waves in a viscous fluid, a numerical study of scaling effects in peristalsis and dynamic suction pumping, and impacts of facilitated urea transporters on the urine-concentration mechanisms in the rat kidney.
In IBS, this process, known as peristalsis, is defective, resulting in abdominal pain and bloating.
The team now plans to modify the capsule so that peristalsis, or contractions of the digestive tract, would slowly squeeze the drug out of the capsule as it travels through the tract.