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GI motility uses both sustained tonic contractions, such as those of sphincters, and rhythmic phasic contractions, such as peristalsis. Interstitial cells of Cajal generate slow waves that set contraction timing, while neural and hormonal signals influence contraction force and activity. Swallowing coordinates esophageal transit with sphincter relaxation. In the stomach, receptive relaxation accommodates incoming contents, antral mixing and retropulsion help process them, and emptying is regulated at the pylorus. The small intestine mixes contents through segmentation, propels them through peristalsis, and uses the migrating motor complex during fasting. In the large intestine, haustration mixes contents and mass movements propel feces; the defecation reflex involves involuntary internal and voluntary external sphincter control.