Stomach
The stomach is part of the digestive system. It is an internal organ between the esophagus and the small intestines. The stomach is the third stage in the digestive process. It holds food after ingestion. Food in the stomach then passes through to the small intestine where most of the food's nutrition is absorbed.
The stomach contains hydrochloric acid made by stomach cells. As a useful side-effect, the acid kills bacteria in the food. However, its main function is to help the protein-digesting enzymes called proteases 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 make peptic ulcers worse. It can also cause heartburn—pain in the chest when acid from the stomach refluxes (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 a symptom 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 by bacteria.
Other words for stomach include belly and tummy.
Stomach Media
Schematic image of the blood supply to the human stomach: left and right gastric artery, left and right gastroepiploic artery and short gastric artery
The gastrointestinal wall of the human stomach
Histology of normal fundic mucosa. Fundic glands are simple, branched tubular glands that extend from the bottom of the gastric pits to the muscularis mucosae; the more distinctive cells are parietal cells. H&E stain.
Histology of normal antral mucosa. Antral mucosa is formed by branched coiled tubular glands lined by secretory cells similar in appearance to the surface mucus cells. H&E stain.
An endoscopy of a normal stomach of a healthy 65-year-old woman
Endoscopic image of a fundic gland polyp
Comparison of stomach glandular regions from several mammalian species. Frequency of glands may vary more smoothly between regions than is diagrammed here. Asterisk (ruminant) represents the omasum, which is absent in Tylopoda (Tylopoda also have some cardiac glands opening onto ventral reticulum and rumen) Many other variations exist among the mammals.
Greater omentum and stomach of humans
