What are the functions of ileum?

The lowest part of small intestine is the ileum. The ileum is the last and longest section of the small intestine.

In ileum, the walls of the small intestine begin to thin and narrow, and blood supply is reduced. Food spends the most time in the ileum, where the most water and nutrients are absorbed.

The ileum helps to further digest food coming from the stomach and other parts of the small intestine. It absorbs nutrients (bile acid, vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. Finger-shaped structures called villi line the entire small intestine. They help absorb nutrients.

The main difference between jejunum and ileum is that jejunum absorbs fully-digested carbohydrates and proteins whereas ileum absorbs the non-absorbed particles from the jejunum.

In case of protein, it starts to break down in the stomach. Absorption of protein starts in duodenum which breakdowns protein into smaller forms called amino acids and these amino acids are finally absorbed by ileum and then they are used by different parts of the body via blood.

In the ileum, segmentation slows down and peristalsis takes over, moving food waste gradually toward the large intestine.
What are the functions of ileum?

Digestion and absorption of carbohydrates

The carbohydrates in the diet are broken down by the enzymes on the mouth, pancreas and intestinal epithelium.

Digestion resumes in the small intestine where more polysaccharide splitting enzymes from the pancreas break the carbohydrate down completely into disaccharides. The enzyme released through the common bile duct into the small intestine.

Then enzymes on the surface of the cells of the small intestine break these into simple sugars or monosaccharaides.  Maltose is split into two glucose molecules; lactose is split into one glucose and one galactose; and sucrose into one glucose and one fructose.

However the great majority of carbohydrates in human meal are digested and absorbed as glucose, if a blood glucose levels are measured before such a meal and at half hourly intervals thereafter, it would show a rise in blood glucose, peaking at about the half hour mark and returning to fasting levels almost as quickly.

If a person were to abstain from carbohydrates for considerable periods say a week, the blood glucose levels would still be normal in spite of a minimal or zero intake.

The active absorption of glucose across the intestinal mucosa is thought to be by phosphorylation in the mucosal cell.

The body’s capacity to maintain blood glucose within specific limits is achieved by a variety of hormones, the two most important of which are insulin and glucagon. Both are secreted by the pancreas into bloodstream, as required.

When the blood glucose level arises, the body adjusts by storing the excess. The frost organ to detect the excess glucose is the pancreas, which releases the hormone insulin in response.
Digestion and absorption of carbohydrates