A student nurse is precepting on the cardiac unit with the charge nurse. The charge nurse is educating the student about heart sounds and asks the student nurse to describe what causes the S1 sound. Which response by the student nurse reflects an understanding of cardiac sounds?

  1. “It is caused by the mitral and tricuspid valves closing.”
  2. “It is caused by the mitral and pulmonic valves closing.”
  3. “It is caused by the pulmonic and aortic valves closing.”
  4. “It is caused by the aortic and tricuspid valves closing.”
Number 1 is correct.
Rationale: The mitral and tricuspid valves produce the S1 sound when they close. Option 3 describes the action that produces the S2 sound. Options 2 and 4 do not describe the mechanism of the S1 heart sound.