Question

In a standard ECG which one of the following alphabets is the correct representation of the respective activity of the human heart?

• A. R – repolarization of ventricles
• B. P – depolarization of the atria
• C. T – end of diastole
• D. S – start of systole

Answer 1

The correct option is B

P – depolarization of the atria

The correct option is B.

Explanation for the correct option:

1. The P Wave is a small upward wave that represents electrical excitation or the atrial depolarization which leads to the contraction of both the atria.
2. It is caused by the activation of the SA node.
3. The impulses of contraction start from the SA node and spread throughout the atria.

Explanation for the incorrect option:

Option A:

1. R represents Ventricular depolarization.
2. It is caused by the impulses of the contraction from the AV node through the bundle of His and Purkinje fibers and the contraction of the ventricular muscles.

Option C:

1. The T wave is dome-shaped which represents ventricular repolarization (ventricular relaxation).
2. The end of the T-wave marks the end of systole.

Option D:

1. The S wave is a downward wave that represents Purkinje fiber's depolarization.

Final Answer: The P wave indicates depolarization of the atria.