Ileum

The final section of the small intestine, critical for nutrient absorption and digestion.

The ileum is the third and final part of the small intestine, following the jejunum. It is approximately 2 to 4 meters long and plays a vital role in the absorption of nutrients, bile salts, and vitamins, particularly B12. The ileum ends at the ileocecal valve, where it connects to the large intestine. Its walls are lined with numerous villi that increase the surface area for nutrient absorption.

Terminologia Anatomica

ileum

System

Digestive system

Function

The primary function of the ileum involves the absorption of various nutrients that remain after digestion in the earlier sections of the small intestine. It is particularly significant for absorbing vitamin B12 and bile acids, which are recycled back to the liver. The ileum also helps in the absorption of fatty acids and monoglycerides resulting from fat digestion, as well as other essential vitamins and minerals. Moreover, the ileum plays a vital role in the immune response, housing Peyer's patches—aggregated lymphoid tissue that monitors intestinal bacteria and prevents the growth of pathogenic bacteria in the intestines, showcasing its function beyond digestion.

Location

Situated in the lower part of the abdomen, the ileum extends from the jejunum to the cecum of the large intestine, located in the right iliac fossa. It occupies the right lower quadrant of the abdominal cavity and loops around the other structures of the small intestine, making its exact positioning somewhat variable depending on individual anatomy. The ileocecal valve, which controls the flow of material from the ileum into the cecum, marks its termination.

Did You Know?

The ileum contains specialized cells called enterocytes that are responsible for nutrient absorption.
Peyer’s patches in the ileum play a significant role in the immune system, acting as a barrier against pathogens.
Unlike the rest of the small intestine, the ileum has a more extensive blood supply to effectively absorb nutrients into the bloodstream.