mom sectionmom sectionIn mammals, including humans, blood courses through the circulatory system, being pumped by a four-chambered heart. When returning to the heart, after delivering nutrients and oxygen to all parts of the body, blood is depleted in oxygen. The lungs are continuously extracting oxygen from the atmosphere to replenish the blood. But in order for this replenishment to take place, the circulatory system must have a way of sending the blood to the lungs to pick up a new supply of oxygen. The heart and a system of arteries and veins perform this function.
Learn about the varying rules of hearts in this free card playing video.
