Thestomach is part of thedigestive system. It is an internal organ between theesophagus and thesmall intestines. The stomach is the third stage in the digestive process. It holdsfood after ingestion. Food in the stomach then passes through to thesmall intestine where most of the food'snutrition is absorbed.
The stomach containshydrochloric acid ofpepsin made by stomachcells. As a useful side-effect, the acid killsbacteria in the food. However, its main function is to help the protein-digestingenzymes calledproteases work. In general, the food is churned, squeezed and mixed. This prepares it for digestion. The partially digested food is called chyme.
The stomach acid may cause problems. It can makepeptic ulcers worse. It can also causeheartburn—pain in the chest when acid from the stomachrefluxes (backs up into) the oesophagus. These can usually be treated by neutralizing the acid.Vomiting occurs when food goes back up the oesophagus and out the mouth. Vomiting can be asymptom of disease.
Stomachs of other mammals work differently to human stomachs.Ruminants, for example, have a stomach with multiple compartments.In that system, food goes through the first part of the digestive system twice, and the work of digesting the grass is done bybacteria.
