Which part of the EKG tracing represents the atrial depolarization?

The P wave represents atrial depolarization in an EKG tracing. During this phase, the atria contract, allowing blood to flow into the ventricles. The P wave is the first positive deflection seen on the EKG, occurring as a result of the electrical impulses generated by the sinoatrial (SA) node, which spread through the atria. This depolarization is crucial because it sets the stage for the following events in the cardiac cycle, specifically the subsequent contraction of the ventricles, which is captured in the QRS complex.

In contrast, the QRS complex represents ventricular depolarization, which is a different electrical event and happens after the P wave. The T wave corresponds to ventricular repolarization, indicating that the ventricles are returning to their resting state after contraction. The baseline serves as a reference point for measuring the waves but does not represent any electrical activity itself. Understanding these components is essential for interpreting EKGs correctly and assessing heart function.