How does food become nutrients the body can use?

Food travels through a tube from the mouth to the stomach and intestines. Digestion breaks food into smaller parts. Absorption is different: small nutrients cross the small-intestine wall into the body. The gut tube and the blood route are separate. Blood can then carry absorbed nutrients toward body cells. Muscular contractions move and mix food along the digestive tract. Mechanical actions and digestive chemicals break large food molecules into smaller components. The small intestine provides an extensive surface for absorption. Many nutrients pass into blood, which carries them toward body tissues; some fats first enter lymph. The large intestine recovers water before remaining material is eliminated.