The second heart sound is caused by
The second is a shorter, high-pitched “dup” (second sound), caused by vibrations associated with closure of the aortic and pulmonary valves just after the end of ventricular systole.
Closure of the aortic and pulmonary valves.
Vibrations in the ventricular wall during systole.
Ventricular filling.
Closure of the mitral and tricuspid valves.