The end of ventricular systole of a cardiac cycle in ECG is marked by

Options

A. QRS complex
B. P wave
C. Q wave
D. T wave

Answer

To determine what marks the end of ventricular systole in a cardiac cycle as represented in an ECG, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Cardiac Cycle**: The cardiac cycle consists of various phases, including atrial contraction, ventricular contraction (systole), and relaxation (diastole). In an ECG, these phases are represented by different waves.

2. **Identifying the Waves**: In an ECG, the main waves are:
- **P wave**: Represents atrial depolarization (contraction of the atria).
- **QRS complex**: Represents ventricular depolarization (contraction of the ventricles).
- **T wave**: Represents ventricular repolarization (relaxation of the ventricles).

3. **Locating Ventricular Systole**: Ventricular systole begins with the QRS complex, which indicates the depolarization of the ventricles. This is when the ventricles contract to pump blood out of the heart.

4. **Identifying the End of Ventricular Systole**: The end of ventricular systole is marked by the repolarization of the ventricles, which is represented by the T wave. This indicates that the ventricles are relaxing after contraction.

5. **Conclusion**: Therefore, the end of ventricular systole in a cardiac cycle is marked by the **T wave**.

### Final Answer:
The end of ventricular systole of a cardiac cycle in ECG is marked by **D, T wave**.

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