Which body system breaks down food into smaller molecules and absorbs nutrients?

• A. Circulatory system
• B. Digestive system
• C. Nervous system
• D. Endocrine system

Answer: (B)

Digestion and nutrient absorption are carried out by the digestive system. It uses both mechanical actions (like chewing and stomach muscles stirring) and chemical ones (enzymes and stomach acid) to break food into tiny molecules such as sugars, amino acids, and fatty acids. The walls of the small intestine, with their tiny finger-like villi, absorb these nutrients into the bloodstream. The circulatory system then carries them to cells throughout the body. The nervous and endocrine systems help regulate digestion, but they don’t perform the breaking-down or absorbing themselves.