Author Question: The second heart sound is associated with what mechanical event of the cardiac cycle? a. ... (Read 74 times)

luminitza · **on:** Jul 16, 2018

The second heart sound is associated with what mechanical event of the cardiac cycle?

a. Atrioventricular valve closure
b. Atrioventricular valve opening
c. Semilunar valve closure
d. Semilunar valve opening

Question 2

The semilunar valves close when which of the following occurs?

a. The pressures in the arteries exceed those in the ventricles.
b. The pressures in the ventricles and arteries become equal.
c. The pressures in the atria exceed those in the ventricles.
d. The pressures in the ventricles exceed those in the atria.

TheDev123 · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

ANS: C
Closure of the semilunar valves generates the second heart sound.

Answer to Question 2

ANS: A
Toward the end of systole, as repolarization starts (indicated by the T wave), the ventricles begin to relax. Consequently, ventricular pressures drop rapidly. When arterial pressures exceed those in the relaxing ventricles, the semilunar valves shut.