what system supplies oxygen to cells
What the Heart and Circulatory System Do. The circulatory system works closely with other systems in our bodies. It supplies oxygen and nutrients to our bodies by working with the respiratory system. At the same time, the circulatory system helps carry waste and carbon dioxide out of the body. Hormones â produced by the endocrine system â are also transported through the blood in the circulatory system. As the body's chemical messengers, hormones transfer information and instructions from one set of cells to another.