Events in the cardiac cycle create recognizable heart sounds. What information should the nurse provide the client about the first heart sound?
A) Produced by the closure of the AV valves when the ventricles contract
B) Produced by the closure of the aortic and pulmonary semilunar valves when the ventricles relax
C) Produced when ventricular filling creates audible vibrations during the silent diastolic phase
D) Produced from turbulent blood flow through the heart's chambers and valves

Question

Quizplus · Accepted Answer

The first heart sound (S1) is produced by the closure of the atrioventricular (AV) valves (mitral and tricuspid valves) at the beginning of ventricular contraction, or systole. This sound is often described as "lub" and signifies the start of systole.

Events in the Cardiac Cycle Create Recognizable Heart Sounds