The second heart sound (S2) occurs because of the closure of the: ...

[Awilson837]

The second heart sound (S2) occurs because of the closure of the:
 
  A. Aortic valve
  B. Tricuspid valve
  C. Aortic and pulmonic valve
  D. A and B

Question 2

The first heart sound (S1) occurs because of the closure of the:
 
  A. Aortic and mitral valves
  B. Mitral and tricuspid valves
  C. Pulmonic valve
  D. Aortic valve

[jesse.fleming]

Answer to Question 1

ANS: C
S1 is the closing of the mitral valve and with the tricuspid (T1) valve; together they are known as the atrioventricular (AV) valves. S2 is the closing of the aortic (A2) and pulmonic (P2) valves; together they are known as the semilunar valves.

Answer to Question 2

ANS: B
S1 is the closing of the mitral valve and with the tricuspid (T1) valve; together they are known as the atrioventricular (AV) valves. S2 is the closing of the aortic (A2) and pulmonic (P2) valves; together they are known as the semilunar valves.

[Awilson837]

Thanks for the timely response, appreciate it

[alvinum]

Excellent