small intestine The part of the gut between the stomach and the large intestine, comprising consecutively the duodenum, jejunum, and ileum. ‘Small’ because it is a narrower tube, though at about twenty feet a much longer one, than the ‘large’ intestine. It is covered by a membrane of peritoneum, and receives its blood vessels and nerves via the mesentery — a flat but fatty double membrane which fans out from the back of the abdomen to the loops of the small intestine. Digestion (started in the stomach) continues here, and absorption begins of the resulting simple nutrient molecules, and of water and minerals. The lining has many folds and protrusions (villi), and secretes mucus and enzymes.

Stuart Judge

small intestine Part of the digestive system that, in humans, extends – about 6m (20ft) coiled and looped – from the stomach to the large intestine, or colon. Its function is the digestion and absorption of food. See also duodenum; ileum

small intestine The portion of the alimentary canal between the stomach and the large intestine. It is subdivided into the duodenum, jejunum, and ileum. It plays an essential role in the final digestion and absorption of food.

small in·tes·tine • n. the part of the intestine that runs between the stomach and the large intestine; the duodenum, jejunum, and ileum collectively.