Question

Which phase of the cardiac cycle is associated with the occurrence of "LUB," the first heart sound?

A) Atrial systole
B) Ventricular systole
C) Ventricular diastole
D) Atrial diastole

Answer 1

The occurrence of the "LUB" sound in the cardiac cycle is associated with ventricular systole, which is when the ventricles contract to pump blood out of the heart.

Step-by-step explanation:

The first heart sound, often described as "LUB," is associated with ventricular systole. This is the phase of the cardiac cycle when the ventricles are contracting to pump blood out of the heart. The occurrence of this sound is due to the closing of the atrioventricular valves, particularly the mitral and tricuspid valves, as the ventricles begin to contract.

Therefore, the correct answer to the question 'Which phase of the cardiac cycle is associated with the occurrence of "LUB," the first heart sound?' is B) Ventricular systole.