Progressive wavelike muscle contractions in the esophagus, stomach, and intestines, and sometimes in the ureters and other hollow tubes. The waves can be short, local reflexes or long, continuous contractions along the length of the organ. In the esophagus, peristaltic waves push food into the stomach. In the stomach, they help mix stomach contents and propel food to the small intestine, where they expose food to the intestinal wall for absorption and move it forward. Peristalsis in the large intestine pushes waste toward the anal canal and is important in removing gas and dislodging potential bacterial colonies.
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Peristalsis is the rhythmic contraction of smooth muscles to propel contents through the digestive tract. The word is derived from New Latin and comes from the Greek peristaltikos, peristaltic, from peristellein, "to wrap around," and stellein, "to place."
In much of the gastrointestinal tract, smooth muscles contract in sequence to produce a peristaltic wave which forces a ball of food (called a bolus while in the esophagus and gastrointestinal tract and chyme in the stomach) along the gastrointestinal tract. Peristaltic movement is initiated by circular smooth muscles contracting behind the chewed material to prevent it from moving back into the mouth, followed by a contraction of longitudinal smooth muscles which pushes the digested food forward.
In the esophagus, two types of peristalsis occur.
As opposed to the more continuous peristalsis of the small intestines, fecal contents are propelled into the large intestine by periodic mass movements. These mass movements occur one to three times per day in the large intestines and colon, and help propel the contents from the large intestine through the colon to the rectum.