What p wave results from?

The P wave on an electrocardiogram (ECG) represents atrial depolarization, which is the electrical activity that triggers the contraction of the atria. It occurs when the sinoatrial (SA) node generates an electrical impulse that spreads through the atria, causing them to contract and push blood into the ventricles. The P wave is typically the first deflection seen on the ECG, preceding the QRS complex.