and each atrium pumps blood into the ventricle below it. During ''ventricular systole'' the ventricles contract and vigorously pulse (or eject) two separated blood supplies from the heart--one to the lungs and one to all other body organs and systems--while the two atria relax (''atrial diastole''). This precise coordination ensures that blood is efficiently collected and circulated throughout the body.

The mitral and tricuspid