What does the ileum do in digestion system?

The ileum is the final portion of the small intestine, located between the jejunum and the large intestine (colon). It plays several important roles in the digestive process:

1. Absorption of Nutrients:

The primary function of the ileum is to absorb essential nutrients from the partially digested food chyme that enters from the jejunum. The majority of water, electrolytes (sodium, potassium, and chloride), vitamins, and minerals are absorbed in the ileum. It also actively absorbs bile salts, vitamin B12, and some carbohydrates (sugars) that were not broken down in the previous parts of the small intestine.

2. Absorption of Fats:

The ileum is responsible for most of the fat absorption that occurs in the small intestine. Fats are broken down into fatty acids and monoglycerides by enzymes produced by the pancreas and the small intestine itself. These breakdown products, along with bile salts, form micelles that aid in the absorption of fats through the intestinal wall.

3. Absorption of Bile Salts:

The ileum plays a crucial role in recycling bile salts, which are necessary for the digestion and absorption of fats. Bile salts are synthesized in the liver and stored in the gallbladder. They help in emulsifying fats, breaking them down into smaller droplets for better digestion by enzymes. Once the micelles release their fatty acid cargo into the intestinal wall, the bile salts are reabsorbed in the ileum.

4. Peristalsis and Segmentation:

The ileum, like other regions of the small intestine, exhibits peristaltic movements to propel the chyme along its length. Peristalsis involves coordinated muscle contractions and relaxations that push the chyme forward. Additionally, the ileum undergoes segmentation, which involves localized contractions and relaxations that mix the intestinal contents, promoting further digestion and absorption.

5. Immune Function:

The ileum contributes to the immune defense system of the digestive tract. Peyer's patches, which are lymphoid tissues found in the ileum, contain immune cells that help protect against harmful bacteria, viruses, and other foreign substances that may enter the digestive system.

Overall, the ileum is a vital component of the digestive system, playing a crucial role in the absorption of essential nutrients, fats, and bile salts. Its functions are critical for the efficient digestion and utilization of the nutrients present in our food.