Ileum
final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds
The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum. Its main function is to absorb vitamin B12, bile salts, and whatever products of digestion that were not absorbed by the jejunum.
The ileum follows the duodenum and jejunum and is separated from the cecum by the ileocecal valve (ICV). In humans, the ileum is about 2–4 m long, and the pH is usually between 7 and 8 (neutral or slightly basic).
Ileum is derived from the Greek word εἰλεός (eileós), referring to a medical condition known as ileus.
Structure
The ileum is the third and final part of the small intestine. It follows the jejunum and ends at the ileocecal junction, where the terminal ileum communicates with the cecum of the large intestine through the ileocecal valve. The ileum, along with the jejunum, is suspended inside the mesentery, a peritoneal formation that carries the blood vessels supplying them (the superior mesenteric artery and vein), lymphatic vessels and nerve fibers.
There is no line of demarcation between the jejunum and the ileum.
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This entry incorporates text from “Ileum” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.