Role of motility in the upper digestive tract.

Oesophageal peristalsis is considered in relation to a central regulatory mechanism and circular smooth muscle contraction after cessation of a neural input. The roles of tonic pressure and transient inappropriate relaxation of the oesophageal sphincter in gastro- oesophageal reflux, and the return of refluxed material to the stomach by secondary peristalsis, are examined. Ingested food is accommodated through vagally mediated relaxation of the proximal stomach in response to swallowing. Gastric peristalsis contributes to the disintegration of solids and the regulation of their emptying from the stomach. In humans, vagotomy initially causes marked delay in gastric emptying, but gradual adaptation occurs and peristalsis improves. The movement of fluid across the pylorus is discussed. Duodenogastric reflux is evidently a normal event.