Final answer:
During the PR interval of an ECG, electrical conduction from atrial depolarization to the start of ventricular depolarization is represented, starting with the P wave and ending at the QRS complex.
Step-by-step explanation:
Electrocardiograms (ECGs) provide a visual representation of the electrical activity happening in the heart. During the PR interval, there is a depiction of the electrical conduction from the beginning of atrial depolarization to the start of ventricular depolarization. This interval includes the P wave, which represents atrial depolarization, and is followed by the PR segment leading to the QRS complex, indicating the initial ventricular depolarization. If there is a delay in the electrical impulse from the sinoatrial (SA) node to the atrioventricular (AV) node, it would be visible in the PR interval.
Moreover, it is important to note that atrial contractions start approximately 25 ms after the P wave begins. The QRS complex signals the depolarization of the ventricles, which requires a stronger electrical signal due to the ventricles' larger muscle mass.