What is the primary function of the jejunum and ileum?

The primary function of the jejunum and ileum is absorption of digested food. These sections of the small intestine have specialized structures, such as villi and microvilli, which increase their surface area and enhance their ability to absorb nutrients effectively. The jejunum is particularly involved in absorbing carbohydrates, amino acids, and vitamins, while the ileum primarily absorbs bile acids and vitamin B12.

While the stomach and the duodenum are primarily involved in digestion and the secretion of digestive juices, the jejunum and ileum focus on transferring the nutrients from the digested food into the bloodstream, ensuring that the body receives the essential components needed for energy, growth, and cellular repair. This distinction emphasizes the specialized role of the jejunum and ileum in the digestive system, positioning them as critical sites for nutrient absorption rather than for food storage or significant digestive processes.