Your blood is carried around your boddy in tubes called blood vessels. This is called the blood system or the circulatory system. The blood system is usefull for transport of oxygen from the lungs to the cells and food from the guts to your cells. Als your blood system is usefull to remove waste chemicals like carbon dioxide from the cells to the lungs and waste chemicals from the cells to your kidneys. The blood system contains arteries, veins, cappilaries, the heart, the lungs and the guts.