Small intestine The soupy mixture called chyme spurts from the stomach through a sphincter into the small intestine. An adult's small intestine is about 23 feet long and is divided into three sections: the first 10 to 12 inches form the duodenum; the next 10 feet form the jejunum; and the final 12 feet form the ileum. The inner surface of the small intestine contains numerous fingerlike projections called villi . Each villus has projections of cells called microvilli to increase the surface area. Most chemical digestion takes place in the duodenum. In this region, enzymes digest nutrients into simpler forms that can be absorbed. Intestinal enzymes are supplemented by enzymes from the pancreas , a large, glandular organ lying near the stomach. In addition, bile enters the small intestine from the gall bladder to assist in fat digestion.
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