The brain is in charge of all the things the body does. Your brain keeps your body alive, makes your heart pump blood, your lungs breathe air, makes your muscles move, controls thinking and senses, etc.
Your heart is always working. It pumps blood to your head, arms, legs and all the inside parts. The body needs this blood because it carries oxygen for energy, the nutrients from digested food for health and collects waste the body does not use for elimination.