What is the state of heart in the interval after end of second heart sound and before beginning of first heart sound again?

Options

A. Ventricle remain systole auricles undergo first diastole and the systole
B. Ventricle remain in diastole, auricles undergoes first diastole and then systole
C. Ventricles undergo first systole and then diastole, auricles remain in diastole.
D. Ventricles remain in diastole, auricles remain in systole.

Answer

To answer the question regarding the state of the heart in the interval after the end of the second heart sound (S2) and before the beginning of the first heart sound (S1) again, we can analyze the cardiac cycle step by step.

### Step-by-Step Solution:

1. **Understanding Heart Sounds**:
- The first heart sound (S1) is produced by the closure of the atrioventricular (AV) valves at the beginning of ventricular systole.
- The second heart sound (S2) is produced by the closure of the semilunar valves at the end of ventricular systole.

2. **Cardiac Cycle Duration**:
- The cardiac cycle lasts approximately 0.8 seconds, which can be divided into phases of systole and diastole for both the atria and ventricles.

3. **Phases of the Cardiac Cycle**:
- Atrial Systole: The atria contract and push blood into the ventricles.
- Ventricular Systole: The ventricles contract to pump blood into the arteries.
- Atrial Diastole: The atria relax and fill with blood.
- Ventricular Diastole: The ventricles relax and fill with blood.

4. **Interval After S2**:
- After S2, the ventricles are in diastole. This is the phase where the ventricles are relaxing and filling with blood from the atria.

5. **Interval Before S1**:
- Before S1, the ventricles are still in diastole, and the atria are in systole, contracting to fill the ventricles with blood.

6. **Conclusion**:
- Therefore, in the interval after the end of S2 and before the beginning of S1, the state of the heart is such that the ventricles are in diastole (relaxing and filling with blood), while the atria are in systole (contracting).

### Final Answer:
The state of the heart in the interval after the end of the second heart sound and before the beginning of the first heart sound is that the ventricles are in diastole and the atria are in systole.