What Is the Ileum?
The ileum in humans is the last and longest part of the small intestine. The ileum measures about 11.5 feet long (3.5 meters) and comprises about 3/5 of the length of the entire small intestine. It extends from the middle section of the small intestine (jejunum) to the ileocecal valve, which leads into the large intestine (colon).
What Is the Purpose of the Ileum?
The primary function of the ileum is to absorb nutrients from digested food (chyme).
- Vitamin B12 is absorbed
- Proteins and peptides are metabolized into amino acids
- Villi, which are finger-like projections that extend from the inner wall of the ileus, help the body absorb fatty acids and glycerol
- The digested fat is emptied into the bloodstream and is transported along with other nutrients to the liver where nutrients are absorbed by the body and toxins are removed
- The ileum secretes protease and carbohydrate enzymes which helps break down carbohydrates into simple sugars, and lipids into glycerol and fatty acids so they can be more easily absorbed by the body
- The ileum also releases certain digestive hormones, including cholecystokinin, gastrin, and secretin
- The last portion of the small intestine is the terminal ileum, which functions to absorb bile salts produced by the liver
- The muscle fibers in the ileum contract regularly (peristalsis) to push remaining undigested food into the large intestine (colon)
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