Which heart sound occurs at the beginning of isovolumetric contraction?Multiple choice question.ThirdFirstSecond

Break Down the Problem

1. Identify the relevant physiological processes associated with heart sounds.
2. Understand the timing of heart sounds during the cardiac cycle.

Relevant Concepts

• The heart sounds are associated with the closing of valves:
  • First heart sound (S1): Closure of the atrioventricular (AV) valves (mitral and tricuspid).
  • Second heart sound (S2): Closure of the semilunar valves (aortic and pulmonary).
  • Third heart sound (S3): Associated with the rapid filling phase of the ventricles.

Analysis and Detail

• Isovolumetric contraction occurs immediately after the closure of the AV valves (S1) and before the opening of the semilunar valves.
• Therefore, during isovolumetric contraction, the first heart sound (S1) is what precedes this phase.

Verify and Summarize

• The first heart sound marks the onset of ventricular contraction where the ventricles begin to contract but all heart valves are closed, leading to an increase in pressure without a change in volume.

Final Answer

The heart sound that occurs at the beginning of isovolumetric contraction is the First heart sound (S1).