Does the small intestine break up molecules?

The small intestine is responsible for breaking down large, complex molecules into smaller, absorbable molecules. This is done through mechanical digestion, chemical digestion, and absorption. Mechanical digestion involves physically breaking down food into smaller pieces through chewing, muscular contractions, and the action of bile. Chemical digestion involves the use of enzymes to chemically break down carbohydrates, proteins, and fats into simpler molecules. Absorption is the process by which these simpler molecules are taken up into the bloodstream through the walls of the small intestine.