The stomach is a hollow organ of the digestive system, in which food is temporarily accumulated, mechanically mixed and processed with gastric juice. The stomach produces hydrochloric acid and digestive enzymes, which create conditions for the initial digestion of proteins. An acidic environment also helps protect the body from many microorganisms ingested with food.
After partial digestion, the food mass passes in small portions to the duodenum, where digestion continues. Stomach disorders can manifest as pain or discomfort in the upper abdomen, heartburn, nausea, early satiety, and a feeling of heaviness after eating.