Which complex on an EKG represents atrial depolarization?

The P wave on an EKG represents atrial depolarization. This is an essential aspect of the cardiac cycle because depolarization of the atria initiates the contraction of the atrial myocardium, allowing blood to flow into the ventricles. The P wave is typically the first small upward deflection on the EKG tracing, reflecting the electrical impulse generated by the sinoatrial (SA) node as it spreads through the atria.

During this process, the atrial muscle fibers become positively charged, leading to contraction and subsequent blood movement into the ventricles. The P wave is distinct and precedes the QRS complex, which signifies ventricular depolarization. Understanding the significance of the P wave in the context of the cardiac cycle helps to interpret the overall rhythm and health of the heart accurately.