The stomach is a J-shaped, pouchlike organ that hangs under the diaphragm in the upper left portion of the abdominal cavity and has a capacity of about 1 liter or more. Thick folds (rugae) of mucosal and submucosal layers mark the stomach's inner lining and disappear when the stomach wall distends. The stomach receives food from the esophagus, mixes the food with gastric juice, initiates protein digestion, does a limited amount of absorption, and moves food into the small intestine.