Which ECG complex represents ventricle contraction?

Which ECG complex represents ventricle contraction?

• A. The P wave represents atrial contraction
• B. The QRS complex represents ventricle contraction
• C. The T wave represents ventricle relaxation
• D. The PR interval represents atrial relaxation

Answer: (B)

Ventricular contraction is triggered by ventricular depolarization, which appears as the QRS complex on the ECG. This rapid spike shows the electrical impulse spreading through the ventricles, prompting them to contract (systole). The P wave above it reflects atrial depolarization and atrial contraction. The T wave after represents ventricular repolarization, meaning the ventricles are relaxing. The PR interval is the time from the start of atrial depolarization to the start of ventricular depolarization and includes the AV node delay, not a contraction by itself.

Ventricular contraction is triggered by ventricular depolarization, which appears as the QRS complex on the ECG. This rapid spike shows the electrical impulse spreading through the ventricles, prompting them to contract (systole). The P wave above it reflects atrial depolarization and atrial contraction. The T wave after represents ventricular repolarization, meaning the ventricles are relaxing. The PR interval is the time from the start of atrial depolarization to the start of ventricular depolarization and includes the AV node delay, not a contraction by itself.