What is the waveform in an ECG that represents atrial depolarization?

The P Wave is the waveform in an ECG that represents atrial depolarization. During this phase, the electrical impulse originating from the sinoatrial node causes the atria to contract, facilitating the movement of blood into the ventricles. This process is essential for effective heart function. The P Wave is typically the first deflection in the ECG tracing and is characterized by a small, rounded shape.

In contrast, the QRS Complex reflects ventricular depolarization, which occurs after atrial depolarization and is responsible for the contraction of the ventricles. The T Wave represents ventricular repolarization, or the recovery phase after contraction, while the ST Segment is the period between ventricle depolarization and repolarization, serving as a flat line in the ECG that indicates a transition between these phases. Thus, correctly identifying the P Wave as the marker for atrial depolarization is vital for understanding heart rhythm and electrical activity as it provides insight into the timing of the cardiac cycle.