Question

The diagram given here is the standard ECG of a normal person. The P-wave represents the

• A. Contraction of both the atria
• B. Initiation of the ventricular contraction
• C. Beginning of the systole
• D. End of systole

Answer 1

The Correct Option is A

To understand the given question, let's analyze the components of a standard ECG (Electrocardiogram) and identify the significance of each wave:

1. P-wave: This wave represents the electrical activity associated with the contraction of the atria. During the P-wave, both right and left atria depolarize and prepare to contract, pushing blood into the ventricles. Hence, the P-wave specifically signifies the contraction of both the atria.
2. QRS complex: This part of the ECG indicates the depolarization of the ventricles, leading to their contraction. It signifies the beginning of ventricular contraction.
3. T-wave: Represents the repolarization (relaxation) of the ventricles. It generally occurs after the QRS complex.

Now, let's evaluate the provided options:

• Contraction of both the atria: Correct answer, as explained above, the P-wave represents this action.
• Initiation of the ventricular contraction: This is represented by the QRS complex, not the P-wave.
• Beginning of the systole: Generally related to the onset of ventricular contraction (QRS complex), not the atrial contraction.
• End of systole: Associated with the T-wave, marking the end of ventricular activity.

Therefore, the correct answer is Contraction of both the atria.