What does the "P" wave on an EKG represent?

The "P" wave on an EKG represents the depolarization of the atria. This electrical activity initiates the contraction of the atrial muscles, leading to the filling of the ventricles with blood. As the atria depolarize, this wave is produced, showing up as the first small deflection on the EKG tracing.

Understanding the function of the "P" wave is crucial, as it indicates the heart's rhythm and health. Proper atrial contraction ensures that there is an efficient flow of blood into the ventricles before they contract. This sequence of electrical events is fundamental to the heart's function and helps in diagnosing various cardiac conditions.

In contrast, other options refer to different parts of the heart's electrical activity. The depolarization of the ventricles is represented by the "QRS" complex, while the contraction of the ventricles is associated with the subsequent phases of the cardiac cycle. The AV node's activity is part of the overall conduction system but is not directly represented by the "P" wave itself. Therefore, recognizing the significance of the "P" wave is essential for understanding atrial activity in an ECG interpretation.