The first heart sound is the closing of the
A) pulmonary semilunar and aortic semilunar valves
B) tricuspid and mitral valves
C) mitral and bicuspid valves
D) tricuspid and pulmonary semilunar valves

Question

Quizplus · Accepted Answer

The first heart sound is caused by the closure of the tricuspid and mitral valves which happens when the ventricles contract and blood is pushed into the aorta and pulmonary artery. Option A is incorrect as these valves close in the second heart sound. Option C is incorrect as mitral and bicuspid valves are the same. Option D is incorrect as the pulmonary semilunar valve does not close during the first heart sound.

The First Heart Sound Is the Closing of the