The marks Diastole . The ventricles relax. But wait—the blood tries to flow backward. Luckily, the pulmonary and aortic valves snap closed to stop it. That snapping echo? That’s your 'Dub.'
"The human heart doesn't sing. It knocks. Two knocks per beat. Lub... Dub. lub dub sounds systole diastole
🔊 This is the loudest sound. It happens when the ventricles contract (Systole). The mitral and tricuspid valves snap shut, pushing blood up and out to your lungs and body. Think of it as the "Push." The marks Diastole