Ileum

Eva Rudolf-Müller is a freelance writer in the medical team. She studied human medicine and newspaper sciences and has repeatedly worked in both areas - as a doctor in the clinic, as a reviewer, and as a medical journalist for various specialist journals. She is currently working in online journalism, where a wide range of medicine is offered to everyone.

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The ileum is the last section of the small intestine after the jejunum. With a length of about three meters, it makes up three fifths of the entire small intestine. In the ileum, as in the rest of the small intestine, digestive processes take place and also the absorption of water and bile acids. Read all about the ileum!

What is the ileum?

The ileum (ileum) covers about the last three meters of the five to six meters long small intestine. It begins after the jejunum (empty intestine), from which it is not clearly delimited.

Like the jejunum, the ileum is attached to the posterior abdominal wall by the mesentery and winds in numerous freely movable loops down to the lower right in the lower abdomen. There the ileum ends with the Bauhin's valve, which represents the transition into the large intestine (more precisely into the appendix = cecum).

In principle, the wall of the ileum is constructed in the same way as that in the rest of the small intestine. However, it is less thick and has fewer folds of the mucous membrane (Kerckring folds) and villi - the inner surface and thus the resorption area is not as enlarged as in the jejunum. This is also not necessary because most of the usable food components are already absorbed into the blood in the duodenum and jejunum.

Instead, the ileum has more lymph follicles (Peyer's plaques) that are supposed to ward off germs ingested with food.

What is the function of the ileum?

Like the rest of the small intestine, the ileum is involved in the absorption of nutrients, albeit to a lesser extent. In the ileum, those substances that could not be absorbed in the duodenum and jejunum are absorbed: electrolytes, vitamins and trace elements.

In the terminal ileum (the last ten to 15 centimeters of the ileum) the reabsorption of the bile acids takes place, which were produced by the liver and packed in the bile and released into the duodenum for fat digestion. After the bile acids have been reabsorbed, they return to the liver via the blood (enterohepatic circulation).

In addition, cobalamin (vitamin B12) is absorbed from food in the terminal ileum.

The ileum also absorbs much of the water that is ingested with food, as well as all digestive secretions that are secreted into the stomach and small intestine. The rest is absorbed in the colon.

Meckel's diverticulum

In about two percent of all people, the ileum has a finger-shaped protuberance on the intestinal wall, about 60 centimeters in front of the Bauhin's valve. This so-called Meckel's diverticulum is the remainder of the embryonic yolk duct that led from the intestine to the navel.

What problems can the ileum cause?

Crohn's disease is a chronic inflammatory bowel disease that can occur in both the large and small intestines. In around 30 percent of the sick, only the ileum is affected.

In the case of an intestinal obstruction, the food pulp can no longer be transported in the intestine - either due to a mechanical obstacle (mechanical ileus) or intestinal paralysis (paralytic ileus). About two thirds of all intestinal occlusions affect the small intestine.

Celiac disease is a genetic intolerance to gluten, the gluten protein in cereals. The immune system of those affected is hypersensitive to gluten with chronic inflammation and destruction of the villi in the small intestine.

A vitamin B12 deficiency can cause anemia (pernicious anemia). It is caused by a resorption disorder in the terminal ileum, which can be caused by inflammation or medication.

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