Normal heart and its section

             

             The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide. The vessels colored red indicate the transport of blood with relatively high content of oxygen and low content of carbon dioxide. Arteries carry blood away from the heart while veins carry blood into the heart. The external structures of the heart include the ventricles, atria, arteries and veins.

             

             Valves, chambers, and associated vessels of hear are seen here.