Final answer:
In a normal, healthy heart, there are two audible heart sounds: S₁ and S₂. S₁ is the sound created by the closing of the atrioventricular valves during ventricular contraction and is described as a "lub." The second heart sound, S₂, is the sound of the closing of the semilunar valves during ventricular diastole and is described as a "dub."
Step-by-step explanation:
In a normal, healthy heart, there are two audible heart sounds: S₁ and S₂. S₁ is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as a "lub," or first heart sound. The second heart sound, S₂, is the sound of the closing of the semilunar valves during ventricular diastole and is described as a "dub."
There is also a third heart sound, S3, which is rarely heard in healthy individuals. It may be the sound of blood flowing into the atria, blood sloshing back and forth in the ventricle, or tensing of the chordae tendineae. S3 is mainly heard in youth, some athletes, and pregnant individuals. If the sound is heard later in life, it may indicate congestive heart failure.