Which part of the ECG represents ventricular depolarization?

• A. The P wave
• B. The T wave
• C. The QRS complex
• D. The ST segment

Answer: (C)

The QRS complex represents ventricular depolarization on an ECG. During this phase, electrical impulses travel through the ventricles, leading to their contraction and the ensuing ejection of blood into the arteries. The QRS complex is characterized by a rapid series of sharp deflections that reflect this fast-moving electrical activity as the ventricles are activated.

Ventricular depolarization is crucial for understanding how heartbeats function, as it initiates the pumping action of the heart. The length and morphology of the QRS complex can provide valuable insights into the heart's condition, such as potential abnormalities in conduction pathways or ventricular hypertrophy.

In contrast, the P wave signifies atrial depolarization, marking the contraction of the atria, while the T wave reflects ventricular repolarization, the phase when the ventricles reset their electrical state after contraction. The ST segment serves as a period of electrical neutrality following the QRS complex, before the next depolarization event. Understanding these distinctions is essential for accurate ECG interpretation.