Lub-dub Sound !!link!! ✦ ❲EXTENDED❳

The mitral and tricuspid valves (atrioventricular valves) snap shut to prevent blood from flowing back into the atria. 2. The "Dub" (S2)

The second sound, known as , is the "dub." This sound signifies the beginning of ventricular diastole , the period when the heart relaxes and refills with blood. lub-dub sound