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.

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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 ?
Myenteric reflex arcs in the gut generate peristalsis and mixing movements, designed to aid digestion and absorption, and to propel the gut contents toward the anus for expulsion.
Effects of an endoscope and magnetic field on peristalsis involving Jeffery fluid.
This initiates peristalsis and exposure of the esophageal mucosa to saliva rich in bicarbonate.
Tasawar Hayat said that the influential topics cover a wide spectrum of subjects including peristalsis, blood flow, gliding motility of bacteria, mathematical modeling, mathematical methods, industrial and environmental heat and mass transfer, deformable porous media, MHD, theology and the mechanics of the porous substrate.
Factors predisposing individuals to GERD include (1) decreased esophageal sphincter pressure, (2) diminished esophageal clearance resulting from defective peristalsis, (3) delayed gastric emptying or abnormal gastric contractility, (4) decreased salivary flow, and (5) increased gastric acid production.
These are also involved in the regulation of physiological functions like gastrointestinal peristalsis.
Lower esophageal sphincter (LES) pressure and percent relaxation, mean peak esophageal body contractions, and percent of swallows with abnormal peristalsis were quantified.
1982) and facilitate their colonization in the small intestine by preventing intestinal peristalsis from removing the ETEC (Isaacson et al.
It is secreted by the enterochromaffin cells of the microvilli and it promotes peristalsis in the GIT.
age-induced decrease in peristalsis, (11) which significantly slows the elimination of enteric pathogens.
Anyway, the boffins say, "When a piece of food is swallowed that is too large for the natural peristalsis of the oesophagus to move the food quickly into the stomach, it applies pressure on the phrenic nerve, invoking the hiccup reflex.
Finally, during the esophageal phase (figure 4), the food or liquid reaches the esophagus, the muscle at the top (called the upper esophageal sphincter) relaxes, and the food is squeezed by peristalsis through to the stomach.