Heart sound notes first year mbbs physiology

Heart sounds are audible vibrations produced by blood flowing through the heart's chambers as the valves open and close. The sounds are often described as a "lub-dub" rhythm: First heart sound (S1) This sound occurs when the mitral and tricuspid valves close, and is associated with the beginning of ventricular systole. S1 is usually high-pitched and split. Second heart sound (S2) This sound occurs when the aortic and pulmonary valves close. S2 is usually louder, crisper, and shorter than S1. Other heart sounds include: Third heart sound (S3): This sound indicates a transition from rapid to slow ventricular filling. Fourth heart sound (S4): This abnormal sound occurs when the atria contract forcefully, but the ventricles don't comply.