Peristalsis

A time-space diagram of a peristaltic wave after a water swallow. High-pressure values are red, zero pressure is blue-green. The ridge in the upper part of the picture is the high pressure of the upper esophageal sphincter which only opens for a short time to let water pass.

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]^{[self-published source?]} 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]

^ Wells, John C. (2008). Longman Pronunciation Dictionary (3rd ed.). Longman. ISBN 978-1-4058-8118-0.
^ Mittal, Ravinder K. (2011). Peristalsis in the Circular and Longitudinal Muscles of the Esophagus. Morgan & Claypool Life Sciences.
^ "Earthworm - Muscular System". www.angelfire.com.
^ Saga, Norihiko; Nakamura, Taro (2004). "Development of a peristaltic crawling robot using magnetic fluid on the basis of the locomotion mechanism of the earthworm". Smart Materials and Structures. 13 (3). IOP Publishing: 566–569. Bibcode:2004SMaS...13..566S. doi:10.1088/0964-1726/13/3/016. Retrieved 2024-04-06.
^ "Online Etymology Dictionary". etymonline.com. Retrieved 2016-06-30.

[1] Wells, John C. (2008). Longman Pronunciation Dictionary (3rd ed.). Longman. ISBN 978-1-4058-8118-0.

[2] Mittal, Ravinder K. (2011). Peristalsis in the Circular and Longitudinal Muscles of the Esophagus. Morgan & Claypool Life Sciences.

[3] "Earthworm - Muscular System". www.angelfire.com.

[4] Saga, Norihiko; Nakamura, Taro (2004). "Development of a peristaltic crawling robot using magnetic fluid on the basis of the locomotion mechanism of the earthworm". Smart Materials and Structures. 13 (3). IOP Publishing: 566–569. Bibcode:2004SMaS...13..566S. doi:10.1088/0964-1726/13/3/016. Retrieved 2024-04-06.

[5] "Online Etymology Dictionary". etymonline.com. Retrieved 2016-06-30.

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