Discuss motility of the digestive tract by explaining the differences between peristalsis and segmentation. Identify the roles of the four major sphincter muscles that divide the GI tract into its principal regions

Answer 1

Motility is the spontaneous movement of the GI tract muscles. Peristalsis is the wavelike muscular contractions of the GI tract that push its contents along. Segmentation is a periodic squeezing or partitioning of the intestine at intervals along its length by its circular muscles. Sphincter muscles periodically open and close, allowing the contents of the GI tract to move along at a controlled pace. The upper esophageal sphincter opens in response to swallowing; the lower esophageal sphincter (also called the cardiac sphincter) prevents reflux of stomach contents; the pyloric sphincter holds chyme in the stomach long enough to be liquefied and prevents intestinal contents from backing up into the stomach; the ileocecal valve allows the contents of the small intestine to empty into the large intestine; two sphincters of the anus prevent continuous elimination.