Describe the main difference between peristalsis and segmentation
What will be an ideal response?
Peristalsis begins in the esophagus, as contractions of circular muscles prevent food from moving backward. Repeated waves of contractions follow as the circular muscles relax and the longitudinal muscles constrict and push the food forward. In the stomach, circular, longitudinal, and diagonal muscles move the food from the top of the stomach toward the pyloric sphincter at the base of the stomach. The waves of contractions in the stomach are slower than in other GI organs, as peristalsis mixes and churns the stomach contents with gastric juices until the food is liquefied. Segmentation moves the food back and forth, helping to break it down into smaller pieces while mixing it with the chemical secretions of the intestine. Segmentation differs from peristalsis in that food is shifted (rather than squeezed) back and forth along the intestinal walls. This shifting action increases the time food is in contact with the intestinal lining, moving food through the small intestine at a rate of 1 centimeter per minute.
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