Peristalsis

Peristalsis is a type of <a href="/facts/Intestinal_motility/DPWGFxhu">intestinal motility</a>, characterized by <a href="/facts/Symmetry_in_biology/FSv5Sv4y">radially symmetrical</a> contraction and relaxation of <a href="/facts/Muscle/dmxrL8pH">muscles</a> that propagate in a <a href="/facts/Wave/fU0HH6St">wave</a> 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.
In much of a <a href="/facts/Digestive_tract/nK2zwqBS">digestive tract</a>, such as the human gastrointestinal tract, <a href="/facts/Smooth_muscle_tissue/mpcpTsHp">smooth muscle tissue</a> contracts in sequence to produce a peristaltic wave, which propels a ball of <a href="/facts/Food/RgNq6NAK">food</a> (called a <a href="/facts/Bolus_(digestion)/sTG2eKpp">bolus</a> before being transformed into <a href="/facts/Chyme/zty06x48">chyme</a> 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.
<a href="/facts/Earthworm/V7IUvWgQ">Earthworms</a> use a similar mechanism to drive their locomotion,[self-published source?] and some modern machinery imitate this design.
The word comes from <a href="/facts/Neo-Latin/mbBrTVEd">Neo-Latin</a> and is derived from the <a href="/facts/Greek_language/pzDd6eIz">Greek</a> peristellein, "to wrap around," from peri-, "around" + stellein, "draw in, bring together; set in order".

Peristalsis open-in-new

Peristalsis