Jejunum vs Ileum

Jejunum refers to the part of the small intestine, which lays just aside the duodenum that leads to the Ileum. The inner lining of the jejunum has a massive area of surface characterizing numerous folds, villi or projections and even microvilli on the villi. On the other hand ileum is the last and the lengthiest part in the small intestine. The ileum is 4 meters long starting from the jejunum leading all the way to the ileocecal valve. This is where the ileum conjoins with the large intestine.

Jejunum is the particular site where all the various processes of digestion and secretion of enzymes continue. Though all these processes originally start in the stomach but they continue in the jejunum. Thereon the absorption of components like amino acids (into the blood capillaries), glucose and fat (into the lymph capillaries) from the digested products also start in the jejunum. On the other hand, Ileum is the site for the assimilation of vitamin B complex or B12 and a second round of absorption of most of the coupled bile salts.

The entire bowel system in the human body which comprise the small intestine includes three distinctive parts, the duodenum, the jejunum and the ileum. The jejunum is the second part in order of occurrence and the ileum is the innermost and the third part lying just before the large intestine.

The jejunum contains minor traces of Mucosa Associated Lymph Tissue or MALT whereas the ileum contains the MALT elements in huge quantities in the structure of Peyer’s patches.

When considering split-open small intestine transplantation, drawing in from just a single donor, the jejunum is more susceptible to a successful operation and transplantation than the ileum.

The Ileum contains an increased number of arterial arcades (p < 0.0001) and arteriae recta (p = 0.02) in comparison to the jejunum. The arterial arcades in the ileum are a lot shorter and narrower than the ones present in the jejunum as well. Definite reasons for such differences are not yet known.

Summary:
1. Jejunum refers to the mid section of the small intestine while ileum is the lengthiest and the last part of the small intestine before the large intestine starts.
2. Digestion and secretion of enzymes take place in the jejunum while absorption of vitamin B ‘“complex and coupled bile salts take place in the ileum.
3. Jejunum has minor traces of Mucosa Associated Lymph Tissue while Ileum has major amounts of Mucosa Associated Lymph Tissue.

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