A long, coiled tube where most chemical digestion and nutrient absorption take place.
Structure
The small intestine measures roughly 6 to 7 meters in adults and is divided into three sections: the duodenum, jejunum, and ileum. Its mucosa is folded into circular ridges and covered with villi and microvilli, expanding the absorptive surface to about 30 square meters.
Digestion
The duodenum receives bile from the liver and digestive enzymes from the pancreas. Enzymes break starches into simple sugars, proteins into amino acids, and fats into fatty acids and glycerol.
Absorption
Nutrients cross the villus surface into capillaries and lacteals. The jejunum handles most absorption, while the ileum recovers bile salts and vitamin B12.
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Small Intestine starts with S and ends with E. Browse other body parts along the same letter.
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