What does the P wave of an ECG represent?

The P wave of an ECG represents atrial depolarization, which is the electrical activity associated with the contraction of the atria, the upper chambers of the heart. When the sinoatrial (SA) node, the natural pacemaker of the heart, generates an electrical impulse, it travels through the atria, causing them to depolarize. This depolarization leads to the contraction of the atrial muscles, pushing blood into the ventricles.

Understanding this aspect of cardiac physiology is crucial, as it sets the stage for the subsequent events in the cardiac cycle, including the QRS complex, which corresponds to ventricular depolarization and contraction. In summary, the P wave is specifically tied to the initiation of the heart's contraction cycle from the atria, making it distinctly significant in the overall function of the heart.