Esophagus a. Transports bolus through the thoracic cavity to the stomach. Rhythmical contractions called peristalsis push food along. Heartburn occurs when stomach acid backs up into esophagus through the lower esophageal sphincter muscle. Vomiting occurs from contraction of abdominal muscles and diaphragm. Stomach a. Thick, J-shaped organ connecting esophagus to duodenum of small intestine.
Structure has deep folds that disappear as the stomach fills.
Columnar epithelial lining contains millions of gastric pits leading to gastric glands. Stomach empties in 2- 6 hours. Chyme leaves the stomach by pyloric sphincter to enter duodenum. Small Intestine a. Provides inner intestine with velvet appearance.