How does absorption take place in the small intestines?

Food that was in the stomach was mechanically churned, mixed with the protein enzyme pepsin as well as hydrochloric acid. At this point in the digestive process, it is a liquid called chyme and is passed into the small intestine.

The small intestine is the site for most of the chemical digestion or hydrolysis of food as well as the absorption of nutrients into the circulatory and lymphatic systems.

The small intestine has villi, which increase surface area for the process of absorption. These are tiny finger-like projections which allow absorption through the intestinal lining. They can do this because they are thin-walled and diffusion can occur through these tiny structures.

Within each villus is a lymphatic vessel called a lacteal, which absorbs fatty acids and allows them to circulate through the lymph and eventually return to the bloodstream.  There are also blood capillaries inside the villus to absorb amino acids and glucose and other nutrients.

The combination of approximately 23 feet of small intestine lined with villi makes the process of chemical digestion and absorption very efficient and greatly increases the surface area for the important work of getting necessary nutrients to the cells of the body.