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Peristalsis

Peristalsis (/ˌpɛrɪˈstælsɪs/ PERR-ih-STAL-siss, US also /-ˈstɔːl-/ -⁠STAWL-)[1] is a type of intestinal motility, characterized by radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which is preceded by a simultaneous contraction of the longitudinal muscle and relaxation of the circular muscle in the lining of the gut.[2]

In much of a digestive tract, such as the human gastrointestinal tract, smooth muscle tissue contracts in sequence to produce a peristaltic wave, which propels a ball of food (called a bolus before being transformed into chyme in the stomach) along the tract. The peristaltic movement comprises relaxation of circular smooth muscles, then their contraction behind the chewed material to keep it from moving backward, then longitudinal contraction to push it forward.


Earthworms use a similar mechanism to drive their locomotion,[3] and some modern machinery imitate this design.[4]


The word comes from Neo-Latin and is derived from the Greek peristellein, "to wrap around," from peri-, "around" + stellein, "draw in, bring together; set in order".[5]

First, there is a primary peristaltic wave, which occurs when the bolus enters the esophagus during . The primary peristaltic wave forces the bolus down the esophagus and into the stomach in a wave lasting about 8–9 seconds. The wave travels down to the stomach even if the bolus of food descends at a greater rate than the wave itself, and continues even if for some reason the bolus gets stuck further up the esophagus.

swallowing

If the bolus gets stuck or moves slower than the primary peristaltic wave (as can happen when it is poorly lubricated), then stretch receptors in the esophageal lining are stimulated and a local reflex response causes a secondary peristaltic wave around the bolus, forcing it further down the esophagus, and these secondary waves continue indefinitely until the bolus enters the stomach. The process of peristalsis is controlled by the medulla oblongata. Esophageal peristalsis is typically assessed by performing an .

esophageal motility study

A third type of peristalsis, tertiary peristalsis, is dysfunctional and involves irregular, diffuse, simultaneous contractions. These contractions are suspect in esophageal dysmotility and present on a barium swallow as a "".[9]

corkscrew esophagus

Machinery[edit]

A peristaltic pump is a positive-displacement pump in which a motor pinches advancing portions of a flexible tube to propel a fluid within the tube. The pump isolates the fluid from the machinery, which is important if the fluid is abrasive or must remain sterile.


Robots have been designed that use peristalsis to achieve locomotion, as the earthworm uses it.[12][13]

Aperistalsis refers to a lack of propulsion. It can result from of the smooth muscle involved.

achalasia

is a slow wave of electrical activity that can initiate a contraction.

Basal electrical rhythm

is a related intestinal muscle process.[8]

Catastalsis

is a disruption of the normal propulsive ability of the gastrointestinal tract caused by the failure of peristalsis.

Ileus

the reverse of peristalsis

Retroperistalsis

are another type of intestinal motility.

Segmentation contractions

Interactive 3D display of swallow waves at menne-biomed.de

at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Peristalsis

Nosek, Thomas M. . Essentials of Human Physiology. Archived from the original on 2016-03-24.

"Section 6/6ch3/s6ch3_9"

Overview at colostate.edu