Body System: Circulatory SystemMain Function: Delivers oxygen and nutrients throughout the body and removes waste products.Main Organ or Part: Heart and blood vessels (arteries and veins)How do the Digestive and Circulatory Systems work together?When food is digested in the digestive system, the intestines transfer the nutrients into the blood. The circulatory system then carries these nutrients to all parts of the body to be used for energy or the creation of new cells. Without the circulatory system, the nutrients from the digestive system cannot be distributed throughout the body.