Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract. It starts in the esophagus where strong wave-like motions of the smooth muscle move balls of swallowed food to the stomach. There, the food is churned into a liquid mixture called chyme that moves into the small intestine where peristalsis continues.
Stretching out a piece of intestine will make it easier to see the wave-like motion. The motion mixes and shifts the chyme back and forth. This lets the bloodstream absorb nutrients through the walls of the small intestine.
In the large intestine peristalsis helps water from undigested food be absorbed into the blood stream. Then, the remaining waste products are excreted through the rectum and anus.
Review Date 8/13/2020
Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.