Why do you need different circuits of blood vessels in your body?

Pulmonary Circulation and Systemic Circulation: The Routes and Function of Blood Flow. Blood must always circulate to sustain life. It carries oxygen from the air we breathe to cells throughout the body. The pumping of the heart drives this blood flow through the arteries, capillaries, and veins. without these we wouldnt have blood to live.

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i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

i would say it is