Anatomy and Physiology II Practice Test 2026 - Free Anatomy Practice Questions and Study Guide

The QRS complex in an ECG tracing is a significant feature that indicates the depolarization of the ventricles. When the heart prepares for contraction, electrical impulses are generated in the heart tissue, and this electrical activity can be observed on the ECG.

During depolarization, the ventricles undergo a rapid electrical change that leads to their contraction, which is crucial for pumping blood out of the heart and into the circulation. The QRS complex reflects this process, characterized by a sharp and rapid deflection on the ECG graph.

The other options relate to different components of the cardiac cycle. For instance, depolarization of the atria is represented by the P wave, while the repolarization of the ventricles is seen in the T wave. Atrial contraction occurs following the P wave and is not specifically denoted by the QRS complex. Understanding the role of the QRS complex helps in diagnosing various cardiac conditions by assessing the electrical activity and contraction of the ventricles.