<prompt> The second heart sound is caused byClosure of the aortic and pulmonary valves.Vibrations in the ventricular wall during systole.Ventricular filling.Closure of the mitral and tricuspid valves.  <response>: 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. 