 Dear students, in this topic we shall discuss the process of peristalsis in detail. Peristalsis involves the continuous contractions and relaxations of circular and longitudinal muscles of the alimenting canal which produce alternating waves of constriction and distension in the lumen. Peristalsis starts from the buccal cavity and continues along the length of esophagus to the stomach and then along the whole of the intestine till the rectum. It is a buccal cavity where the muscular wave continues till the end of rectum. This is called peristalsis. Dear students, peristalsis depends on the arrangement of smooth muscles in the alimenting canal wall. The elementary smooth musculature consists of an inner circular layer of smooth muscles and an outer longitudinal layer of smooth muscles. When the inner circular layer contracts, outer longitudinal layer relaxes. This coordination produces constriction in the lumen. When the longitudinal layer relaxes, the circular layer relaxes. Peristalsis pushes the food along the alimenting canal from the mouth to the anus. Food's movement direction is dependent on the direction of peristaltic wave. Because the root of peristalsis or the direction of this wave moves along the buccal cavity to the anus. Peristalsis induces swallowing, i.e. food is ingested and this process culminates in defecation. Dear students, if the direction of peristalsis reverses, it is called reverse peristalsis. As a result of reverse peristalsis, the luminal contents, which have gone into the digestive tract, they come back into the buccal cavity. Ruminant mammals have a common and normal process in which they can regurgitate their food, i.e. bring up the undarrested or un-chewed food for further chewing in the buccal cavity. But if this process happens in other animals, then it results in vomiting or amesis.