Duration between first and second heart sound is nearly equal to duration of

Options

A. Atrial systole
B. Atrial diastole
C. ventricular systole
D. ventricular diastole

Answer

To solve the question regarding the duration between the first and second heart sounds, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Heart Sounds**: The heart produces two primary sounds known as "lub" (S1) and "dub" (S2). The first sound (S1) is associated with the closing of the atrioventricular valves (mitral and tricuspid valves) at the beginning of ventricular contraction (systole). The second sound (S2) is associated with the closing of the semilunar valves (aortic and pulmonary valves) at the end of ventricular contraction.

2. **Duration of Heart Sounds**: The duration between the first heart sound (S1) and the second heart sound (S2) is approximately 0.20 seconds. This interval represents the time taken for the heart to complete a cycle of contraction and relaxation.

3. **Identify Cardiac Phases**: During the cardiac cycle, there are phases of systole (contraction) and diastole (relaxation) for both the atria and ventricles. The question specifically asks for the duration that is nearly equal to the interval between S1 and S2.

4. **Focus on Ventricular Phases**: The interval between S1 and S2 primarily corresponds to the duration of ventricular systole (the contraction phase of the ventricles) and the beginning of ventricular diastole (the relaxation phase). However, the question asks for a specific duration that matches this interval.

5. **Conclusion**: The duration between the first and second heart sounds is nearly equal to the duration of **ventricular diastole**. This is because after the ventricles contract (systole), they enter a relaxation phase (diastole), which is where the heart is filling with blood again.

### Final Answer:
The duration between the first and second heart sound is nearly equal to the duration of **ventricular diastole**.

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