The left ventricle pumps the oxygen-rich blood to all parts of the body. Do right and left seem backward? That's because you're looking at an illustration of somebody else's heart. To think about ...

Find out about the different stages of a human ... system. What is the circulatory system? Find out how the circulatory system takes oxygen around the body. What is in your blood?

Day and night, the muscles of your heart contract and relax to pump blood throughout your body. When blood returns to the heart, it follows a complicated pathway. If you were in the bloodstream ...