The ileum's the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine aren't as clear and the terms posterior intestine or distal intestine may be used instead of ileum. The ileum follows the duodenum and jejunum, and's separated from the cecum by the ileocecal valve (ICV). In humans, the ileum's about 2-4 m long, and the pH's usually between 7 and 8 (neutral or slightly alkaline). Function The func… (More on Ileum)