The Circulatory System is the main transportation and cooling system for the body. The Red Blood Cells act like billions of little UPS trucks carrying all sorts of packages that are needed by all the cells in the body. Instead of UPS, there called RBC's. RBC's carry oxygen and nutrients to the cells. Every cell in the body requires oxygen to remain alive. Besides RBC's, there are also White Blood Cells moving in the circulatory …showed first 75 words of 885 total…

…showed last 75 words of 885 total…the opening of the Aorta that prevent the blood from backing up into the ventricle. As soon as the blood is in the aorta, there are arteries called coronary arteries that take some of the blood and use it to nourish the heart muscle. Remember: the heart is like James Brown, it's the hardest working muscle in the body (in case you don't know, James Brown says he's the hardest working man in show business).