[Verse 1] Every heart valve has a simple task to do Let the blood flow forward, block the backward too Four guardians working in perfect harmony Keeping circulation flowing naturally [Chorus] Open when it's time to go Close when it's time to hold Semilunar, AV too Forward flow and backward block That's what normal valves all do Forward flow and backward block [Verse 2] Aortic and pulmonary, semilunar style Three cusps shaped like crescents, half-moon profile When ventricles contract, pressure makes them swing When diastole arrives, they snap shut with a ring [Chorus] Open when it's time to go Close when it's time to hold Semilunar, AV too Forward flow and backward block That's what normal valves all do Forward flow and backward block [Verse 3] Mitral and tricuspid, AV design Chordae tendineae keep them in perfect line Papillary muscles anchor them in place Stop prolapse backward, keep them in their space [Bridge] S2 is the sound when semilunar close Aortic first, then pulmonary follows Split timing normal, that's the way it goes Regurgitation leaks, stenosis narrows [Verse 4] When valves start failing, hearts must work much harder Leaking blood backward or restriction's barrier Regurgitation means the valve won't hold Stenosis means it's narrow, won't unfold [Final Chorus] Open when it's time to go Close when it's time to hold Four valves working as they should Forward flow and backward block Keep the circulation good Forward flow and backward block [Outro] Simple job for every valve Forward flow and backward solve
← 1 Normal Fetal Cardiac Development | 2 Normal Four-Chamber Heart Anatomy →