Blood is needed to keep us alive. It brings oxygen and nutrients to all the parts of the body so they can keep working. Blood carries carbon dioxide and other waste materials to the lungs, kidneys,  to be removed from the body. Blood also fights infections, and carries hormones around the body.

Blood Provides the Body's Cells with Oxygen and Removes Carbon Dioxide. Blood absorbs oxygen from air in the lungs. It transports the oxygen to cells throughout the body, and it removes waste carbon dioxide from the cells. In the lungs, the carbon dioxide moves from the blood to the air and is exhaled.

Blood is needed to keep us alive. It brings oxygen and nutrients to all the parts of the body so they can keep working. Blood carries carbon dioxide and other waste materials to the lungs, kidneys, to be removed from the body. Blood also fights infections, and carries hormones around the body.