The repolarization phase of cardiac cycle is represented by which portion of a ECG

Options

A. P
B. QRS
C. S
D. T

Answer

To determine which portion of the ECG represents the repolarization phase of the cardiac cycle, we can analyze the different components of the ECG waveform.

### Step-by-Step Solution:

1. **Understanding the ECG Waves**: The ECG (electrocardiogram) consists of several waves, including the P-wave, QRS complex, and T-wave. Each of these waves corresponds to different electrical activities of the heart.

2. **Identifying the P-Wave**: The P-wave represents atrial depolarization, which is the electrical activity that leads to the contraction of the atria. Since this wave is associated with depolarization, it does not represent repolarization.

**Hint**: Remember that depolarization refers to the contraction phase of the heart.

3. **Analyzing the QRS Complex**: The QRS complex represents ventricular depolarization, which is the electrical activity that leads to the contraction of the ventricles. Like the P-wave, this complex is also related to depolarization and not repolarization.

**Hint**: The QRS complex is crucial for understanding how the ventricles contract.

4. **Considering the S-Wave**: The S-wave is part of the QRS complex and also represents ventricular depolarization. Therefore, it cannot represent repolarization.

**Hint**: The S-wave is included in the QRS complex, so it shares the same function.

5. **Identifying the T-Wave**: The T-wave represents ventricular repolarization, which is the phase where the ventricles relax after contraction. This is the electrical activity that signifies the heart is returning to its resting state.

**Hint**: Look for the wave that indicates the heart is relaxing, which is associated with repolarization.

6. **Conclusion**: Based on the analysis of the ECG components, the repolarization phase of the cardiac cycle is represented by the T-wave.

### Final Answer:
The repolarization phase of the cardiac cycle is represented by the **T-wave** in an ECG.