Ileum

The ileum is an organ belonging to the digestive system.

Function of the ileum

The ileum is the third and final part of the small intestine that follows on directly from the jejunum and continues into the first part of the colon, the caecum. Its function is to continue to absorb nutrients, particularly water, vitamin B12, electrolytes (potassium, sodium…), and bile salts through its villi and microvilli. An ileo-caecal sphincter controls passage of the food bolus into the colon.

The ileum differs from other segments of the intestine as it contains Peyer's patches (aggregates of lymphoid tissue containing lymphocytes to provide immune protection) beneath the intestinal mucosa.

The pH of the ileum is neutral or slightly alkaline (between 7 and 8).

Structure of the ileum

The ileum is more than 4 metes long and is thinner than the jejunum. It is also paler in colour than the jejunum.

The ileum contains smooth muscles providing peristaltic movements.