What is the primary function of the small intestine in the digestive system?

The primary function of the small intestine in the digestive system is chemical digestion and absorption. The small intestine is a crucial site where the majority of nutrient absorption occurs after food has been mechanically broken down in the mouth and stomach.

As food enters the small intestine, it mixes with digestive enzymes from the pancreas and bile from the liver. These substances facilitate chemical digestion, breaking down complex molecules such as carbohydrates, proteins, and fats into simpler forms that can be absorbed.

Once food is adequately digested, the walls of the small intestine—lined with tiny projections called villi and microvilli—maximize the surface area for absorption. This allows nutrients to be efficiently taken up into the bloodstream and transported to the cells throughout the body, where they are used for energy, growth, and cellular repair.

The small intestine also plays a role in regulating the flow of materials further along the digestive tract, but its primary and most critical functions center around breaking down food chemically and facilitating nutrient absorption.