Question

Why can the lubb and dup sound be heard?

Answer 1

Hint: The sounds reflect the turbulence created when the heart valves snap shut. In cardiac auscultation, an examiner may use a stethoscope to listen for these unique and distinct sounds that provide important auditory data regarding the condition of the heart.

Complete Answer:
- Heart sounds are generated by the turbulence created by blood flowing through the heart, specifically when the heart valves close. Normal heart sounds can be characterized by a "lub" "dub" that occurs with a heart beat.
- The lubb and dup sounds of the heart are monitored by the stethoscope. The first sound comes because of the closure of the atrio-ventricular valves. It happens at the opening of ventricular systole.
- The second sound of dup is of high key. It happens by the closure of the partially lunar valves in the pulmonary artery and the aorta. It opens at the opening of the ventricular diastole.

Note: In adults, there are two usual heart sounds, normally known as lub and dub that happens in series with every heartbeat. These are the first heart sound ($S_1$) and second heart sound ($S_2$), occurred by the blocking of the atrioventricular valves and partially lunar valves, respectively. In addition to these normal sounds, a variety of other sounds may be present including heart murmurs, adventitious sounds, and gallop rhythms $S_3$ and $S_4$.