Your heart is like a pumping station for the body, delivering blood to the lungs where it’s enriched with oxygen, then forwarding the oxygenated blood to the rest of the body to nourish your cells. It’s a sophisticated engineering feat, starting with the valves that must open and close on time to keep the little pumping station operational.
The beginning of each heartbeat is marked by blood returning from the body and lungs. Two valves are located at the bottom of the heart’s upper chambers, the mitral and tricuspid valves. As the blood builds up in the upper chambers (the atria) these valves open to allow the blood to flow into the two lower chambers (the ventricles). As the ventricles contract, the mitral and tricuspid valves clamp shut. This prevents blood from flowing back into the atria.