Title: 18.5: Lower Gastrointestinal Tract - Biology LibreTexts
Headings: 18.5: Lower Gastrointestinal Tract
18.5: Lower Gastrointestinal Tract
What Is It?
Organs of the Lower Gastrointestinal Tract
Small Intestine
Duodenum
Digestion of Carbohydrates in the Duodenum
Digestion of Proteins in the Duodenum
Digestion of Lipids in the Duodenum
Jejunum
Ileum
Large Intestine
Parts of the Large Intestine
Functions of the Large Intestine
Feature: My Human Body
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Content: All nutrients are absorbed into the blood except for fatty acids and fat-soluble vitamins, which are absorbed into the lymph. Although most nutrients are absorbed in the jejunum, there are a few exceptions: Iron is absorbed in the duodenum. Vitamin B12 and bile salts are absorbed in the ileum. Water and lipids are absorbed throughout the small intestine, including the duodenum and ileum in addition to the jejunum. Ileum
The ileum is the third and final part of the small intestine, directly connected at its distal end to the large intestine. The ileum is about 3 m (9.8 ft) long. Some cells in the lining of the ileum secrete enzymes that catalyze the final stages of digestion of any undigested protein and carbohydrate molecules. However, the main function of the ileum is to absorb vitamin B12 and bile salts. It also absorbs any other remaining nutrients that were not absorbed in the jejunum.