Cardiac Cycle vs Heart Sounds

A comparison of the cardiac cycle and heart sounds visually links mechanical events in the heart to what is heard through a stethoscope. The diagram aligns phases such as atrial contraction, ventricular systole, and ventricular relaxation with the familiar “lub-dub” sounds. It shows how the first heart sound corresponds to the closing of the atrioventricular valves, while the second sound marks the closure of the semilunar valves. Timing bars or waveforms often appear alongside valve positions and pressure changes, helping clarify why heart sounds occur when they do. By placing sound, motion, and pressure on the same timeline, the illustration makes it easier to understand murmurs, abnormal sounds, and how valve problems affect the cardiac cycle.