Final answer:
The majority of nutrient absorption in the small intestine occurs through the villi, which are microscopic projections in the mucosa. They contain capillaries and lacteals that transport absorbed nutrients into the bloodstream and lymphatic system.
Step-by-step explanation:
Absorption in the Small Intestine
Most absorption takes place through microscopic, fingerlike projections called villi in the mucosa of the small intestine. Each of these villi is covered with even tinier projections known as microvilli, which further increase the surface area for nutrient absorption. The villi contain networks of capillaries and lymphatic vessels, enabling the transfer of nutrients into the blood and lymphatic systems. Specifically, fats are absorbed by the lymphatic capillaries known as lacteals, while carbohydrates, proteins, and other substances pass into the bloodstream directly through the villi's capillaries.