We know that arteries from the aorta and arteries from coronary arteries supply oxygenated blood to various parts of the body. What separates these two is the coronary arteries’ ability to deliver oxygenated blood to the heart. We know that the inferior vena cava delivers deoxygenated blood to the lower (hence inferior) part of the body and that the superior vena cava delivers deoxygenated blood to the upper (superior) part of the body; they follow the same deoxygenated rule and strictly deliver nutrients to certain parts of the body.
The circulatory system moves oxygenated blood to all parts of the body. Without oxygen being carried to cells they would die thus causing the animal to die.