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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.
This entry comes from Encyclopædia Britannica Concise. For the full entry on peristalsis, visit Britannica.com.