Regurgitation and rumination

[Michiko]

Regurgitation is the spitting up of food from the esophagus or stomach without nausea or forceful contractions of the abdominal muscles. Rumination is regurgitation with no apparent physical cause.
A ring-shaped muscle (sphincter) between the stomach and esophagus normally helps prevent regurgitation. Regurgitation of sour-tasting or bitter-tasting material can result from acid coming up from the stomach. Regurgitation of tasteless fluid containing mucus or undigested food can result from a narrowing (stricture) or a blockage of the esophagus or from an abnormal pouch in the esophagus called a Zenker diverticulum. The blockage may result from acid damage to the esophagus, ingestion of caustic substances, cancer of the esophagus, or abnormal nerve control that interferes with coordination between the esophagus and its sphincter at the opening to the stomach (achalasia).