Final answer:
The P wave represents atrial depolarization, the QRS complex represents ventricular depolarization, and the T wave symbolizes ventricular repolarization on an ECG.
Step-by-step explanation:
The P-wave, QRS complex, and the T wave on an electrocardiogram (ECG) represent specific electrical activities within the heart. The P wave indicates the depolarization of the atria, which is the signal that precedes the contraction of the atria, pushing blood into the ventricles.
Following this, the QRS complex represents the depolarization of the ventricles, a much larger and stronger signal compared to the P wave due to the larger muscle mass of the ventricles. The QRS complex peaks with the R wave, signaling the ventricles to contract and pump blood to the lungs and the rest of the body.
Lastly, the T wave signifies the repolarization of the ventricles, indicating the period when the ventricles relax. The repolarization of the atria actually occurs during the QRS complex but is obscured by the larger signal of the ventricular depolarization.