The sequential eventn in the heart which is cyclically repeated is called :-

Options

A. Systole of both atria
B. Diastole of both atria
C. Systoel of both ventricles
D. Cardiac cycle

Answer

**Solution:**

The question is asking about the sequential events in the heart that are cyclically repeated. The correct term for this is the **cardiac cycle**.

1. **Definition of Cardiac Cycle**: The cardiac cycle refers to the series of events that occur in the heart during one complete heartbeat. It includes both contraction and relaxation phases.

2. **Components of the Cardiac Cycle**:
- **Systole**: This is the phase where the heart muscles contract. It can be further divided into:
- **Atrial Systole**: The contraction of the atria (upper chambers) which lasts about 0.1 seconds.
- **Ventricular Systole**: The contraction of the ventricles (lower chambers) which lasts about 0.3 seconds.
- **Diastole**: This is the phase where the heart muscles relax. It can also be divided into:
- **Atrial Diastole**: The relaxation of the atria which lasts about 0.7 seconds.
- **Ventricular Diastole**: The relaxation of the ventricles which lasts about 0.5 seconds.

3. **Duration of the Cardiac Cycle**: The entire cardiac cycle lasts approximately 0.8 seconds, during which both systolic and diastolic phases occur.

4. **Conclusion**: Since the question specifically asks for the term that describes the cyclically repeated events in the heart, the answer is **cardiac cycle**.

**Final Answer**: The sequential events in the heart which are cyclically repeated is called the **cardiac cycle**.

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