In the human body, the site of absorption of digested food is the small intestine. How is the process of absorption carried out, and why is the absorption of digested food necessary?

The inner walls of the small intestine have villi, which are finger-like projections that increase surface area for absorption.

These villi contain blood vessels that absorb nutrients via diffusion or active transport into the bloodstream.

Absorption is necessary because digested food contains nutrients like glucose, amino acids, fatty acids, vitamins, and minerals which are required for energy, growth, and repair of the body.