Question

In ECG, the P wave corresponds to the following event

• A. Atrial depolarisation
• B. Ventricular depolarisation
• C. Atrial repolarisation
• D. Ventricular repolarisation

Answer 1

The Correct Option is D

The given question asks about the P wave in an ECG (Electrocardiogram) and its correspondence to a specific cardiac event. Let's analyze the options to identify the correct answer:

1. Atrial Depolarisation: The P wave in an ECG represents the depolarisation of the atria. This is a key phase where the atrial muscles are activated, leading to their contraction, which pushes blood into the ventricles. Therefore, this is the correct answer.
2. Ventricular Depolarisation: Ventricular depolarisation is represented by the QRS complex in an ECG, not by the P wave. Thus, this option is incorrect for the P wave.
3. Atrial Repolarisation: Atrial repolarisation is not specifically represented as a separate wave on the ECG; it occurs during the QRS complex but is masked by larger ventricular electrical activities. It is not represented by the P wave.
4. Ventricular Repolarisation: Ventricular repolarisation is shown by the T wave on an ECG, not the P wave. Hence, this is not the correct answer to what the P wave represents.

The P wave is the first deflection seen in a cardiac cycle on an ECG, and it specifically corresponds to atrial depolarisation. The reason for this correspondence is the initiation of electrical conduction in the heart, starting from the sinoatrial (SA) node, which causes the atria to depolarise and contract.

Thus, the correct answer here is: Atrial depolarisation.