Anatomic.us > Digestive System

Ileum

The word Ileum itself is of Latin origin. Including Mammals, Reptiles, Birds and higher vertebrates, Ileum is the final section of small intestine. Separated from Colon by the Ileocecal valve (ICV) Ileum follows Jejunum and Duodenum.

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Ileum


ANATOMY

It is found in the Pelvis and the lower part of the Peritoneal Cavity. The length of Ileum in humans is from 2 meter to 4 meter and the pH level is in between 7 and 8 which is neutral or slightly Alkaline.

There is no definite distinction between Ileum and Jejunum but there are some differences to distinguish both i.e.

  • Ileum has more fat than Jejunum in the Mesentery.

  • Ileum is supplied with Mesenteric and Antimesenteric vascular supply while Jejunum has only Mesenteric Vascular supply.

  • In the Mucous membrane of the lower Ileum has Lymphoid Tissues known as Peyer’s Patches (Lymphoid Nodules containing large number of Lymphocytes and other cells of Immune system).

  • Mesentery of Ileum is attached to the right side of Aorta.

 

DEVELOPMENT

In the fetus Ileum is connected to Navel (Belly button, scar on the Abdomen) by Vitelline Duct  (Omphalomesenteric Duct).

 

BLOOD SUPPLY

Ileum’s blood supply comes from the branches of Superior Mesenteric Artery (SMA). These branches originate from left side of the SMA and running through the mesentery reach the Intestinal Wall. In addition to the main blood supply Ileum is supplied by Ileocolic Artery near the Ileocecal Junction. The veins of Ileum are in correspondence to the arteries and drain into Superior Mesenteric Vein.

 

LYMPH DRAINAGE

Lymphatic from Ileum after passing through a number of Intermediate Mesenteric Nodes drain into the Superior Mesenteric Nodes.

 

INNERVATION

Innervations to Ileum are supplied with both Sympathetic and Parasympathetic fibers coming from Superior Mesenteric Plexus.

 

FUNCTION

The main function of Ileum is to absorb the vitamin B12 and Bile Salts and also whichever nutrients of digested food not absorbed by Jejunum. The wall of the Ileum has folds, each of which has finger like projections known as Villi. The Epithelial cells lining these Villi have large number of Microvilli themselves. That’s why Ileum has the large surface area for absorption of Enzymes molecules and other products of digestion. Cells of Ileum secrete various hormones into the blood i.e.

  • Gastrin

  • Secretin

  • Cholecystokinin

Lining of the Ileum also secretes enzymes responsible for the Protein and Carbohydrate digestion into the Lumen of intestine. These enzymes are as follows.

  • Protease Enzyme

  • Carbohydrase Enzyme

 

PATHOLOGY

Patients suffering from Ulcerative Colitis (UC) develop inflammation in the distal Ileum caused by Backwash of the Cecal Contents (Backwash Ileitis). In 2% humans the Vitelline duct fails to close resulting in condition named as Meckel’s Diverticulum (bulge in the small intestine at the time of birth).

 



ANATOMY

It is found in the Pelvis and the lower part of the Peritoneal Cavity. The length of Ileum in humans is from 2 meter to 4 meter and the pH level is in between 7 and 8 which is neutral or slightly Alkaline.

There is no definite distinction between Ileum and Jejunum but there are some differences to distinguish both i.e.

  • Ileum has more fat than Jejunum in the Mesentery.

  • Ileum is supplied with Mesenteric and Antimesenteric vascular supply while Jejunum has only Mesenteric Vascular supply.

  • In the Mucous membrane of the lower Ileum has Lymphoid Tissues known as Peyer’s Patches (Lymphoid Nodules containing large number of Lymphocytes and other cells of Immune system).

  • Mesentery of Ileum is attached to the right side of Aorta.

 

DEVELOPMENT

In the fetus Ileum is connected to Navel (Belly button, scar on the Abdomen) by Vitelline Duct  (Omphalomesenteric Duct).

 

BLOOD SUPPLY

Ileum’s blood supply comes from the branches of Superior Mesenteric Artery (SMA). These branches originate from left side of the SMA and running through the mesentery reach the Intestinal Wall. In addition to the main blood supply Ileum is supplied by Ileocolic Artery near the Ileocecal Junction. The veins of Ileum are in correspondence to the arteries and drain into Superior Mesenteric Vein.

 

LYMPH DRAINAGE

Lymphatic from Ileum after passing through a number of Intermediate Mesenteric Nodes drain into the Superior Mesenteric Nodes.

 

INNERVATION

Innervations to Ileum are supplied with both Sympathetic and Parasympathetic fibers coming from Superior Mesenteric Plexus.

 

FUNCTION

The main function of Ileum is to absorb the vitamin B12 and Bile Salts and also whichever nutrients of digested food not absorbed by Jejunum. The wall of the Ileum has folds, each of which has finger like projections known as Villi. The Epithelial cells lining these Villi have large number of Microvilli themselves. That’s why Ileum has the large surface area for absorption of Enzymes molecules and other products of digestion. Cells of Ileum secrete various hormones into the blood i.e.

  • Gastrin

  • Secretin

  • Cholecystokinin

Lining of the Ileum also secretes enzymes responsible for the Protein and Carbohydrate digestion into the Lumen of intestine. These enzymes are as follows.

  • Protease Enzyme

  • Carbohydrase Enzyme

 

PATHOLOGY

Patients suffering from Ulcerative Colitis (UC) develop inflammation in the distal Ileum caused by Backwash of the Cecal Contents (Backwash Ileitis). In 2% humans the Vitelline duct fails to close resulting in condition named as Meckel’s Diverticulum (bulge in the small intestine at the time of birth).

 

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