The Circulatory System


Heart Parts

The heart is made up of four different blood-filled areas, and each of these areas is called a chamber.The two chambers on top are called the atria (say: ay-tree-uh).If you're talking only about one, call it an atrium.The two chambers on the bottom are called the ventricles (say: ven-trih-kulz).Running down the middle of the heart is a thick wall of muscle called the septum (say: sep-tum).The atria and ventricles work as a team — the atria fill with blood, then dump it into the ventricles.Two of the heart valves are the mitral (say: my-trul) valve and the tricuspid (say: try-kus-pid) valve.The other two are called the aortic (say: ay-or-tik) valve and pulmonary (say: pul-muh-ner-ee) valve, and they're in charge of controlling the flow as the blood leaves the heart.