What happens with the ileum during digestion?

The ileum is the final section of the small intestine and plays a crucial role in the digestion and absorption of nutrients. Here's an overview of what happens in the ileum during digestion:

1. Digestion of Carbohydrates, Proteins, and Fats: The ileum receives partially digested food from the jejunum. Carbohydrates, proteins, and fats that have not been fully broken down in the previous parts of the small intestine continue to undergo digestion in the ileum. Enzymes produced by the pancreas and the lining of the ileum help break down these nutrients into smaller, absorbable molecules.

2. Absorption of Nutrients: The ileum is responsible for the majority of nutrient absorption in the small intestine. The inner lining of the ileum is covered in small, finger-like projections called villi, which increase the surface area for absorption. Nutrients such as amino acids, simple sugars, vitamins, minerals, and water are absorbed through the villi into the bloodstream.

3. Absorption of Bile Salts: Bile salts, produced by the liver and stored in the gallbladder, aid in the digestion and absorption of fats. They help break down fat molecules into smaller particles that can be more easily absorbed. In the ileum, bile salts are reabsorbed and returned to the liver through enterohepatic circulation, where they can be reused.

4. Movement of Digested Food: Peristaltic contractions, rhythmic muscle movements, help move the digested food material through the ileum. Undigested material and water move towards the large intestine (colon) for further processing and eventual elimination.

5. Immune Function: The ileum also plays a role in the immune system. It contains specialized immune cells that help protect the body against harmful bacteria and other pathogens present in the digestive tract.

After completing its functions in digestion and absorption, the remaining indigestible material passes from the ileum into the large intestine to continue the digestive process.