Most digestion occurs when food reaches the small intestine. As food passes through the small intestine, it continues to be broken down by enzymes produced in the small intestine itself and by those produced in the liver and passed to the small intestine. The nutrients broken down by digestion are absorbed into the body through the walls of the small intestine. Blood in tiny blood vessels in the intestinal walls, called capillaries, picks up the nutrients from the digested food and takes them to cells throughout the body where they can be used. The food is continuously broken down until the nutrients are in a form that is usable by the cells of the body.