Decoding the Cardiac Conduction System and ECG

The cardiac conduction system includes the SA node, AV node, AV bundle, and Purkinje fibers, which coordinate heartbeats. The SA node acts as the heart's pacemaker, initiating electrical impulses that cause atrial contraction. The AV node delays these impulses to ensure proper blood flow before ventricular contraction. The AV bundle and Purkinje fibers distribute signals to the ventricles. An ECG records these electrical activities, with specific waves representing different phases of the cardiac cycle, such as the P wave for atrial depolarization and the QRS complex for ventricular depolarization.

What is the primary function of the SA node?

• It records the heart's electrical activity.

• It serves as the heart's natural pacemaker.

• It conducts impulses to the apex of the heart.

• It delays electrical impulses to the ventricles.

Where is the AV node located?

• Within the ventricular myocardium.

• At the apex of the heart.

• On the other side of the right atrium, near the AV valve.

• Near the entrance of the superior vena cava.

Which component of the cardiac conduction system serves as the electrical gateway to the ventricles?

• SA node

• AV node

• Purkinje fibers

• Bundle of His

What is the primary purpose of the delay caused by the AV node?

• To initiate the heartbeat.

• To synchronize the heartbeat with the respiratory rate.

• To allow the ventricles to fill with blood before they contract.

• To ensure the atria contract before the ventricles.

What is the role of the AV bundle?

• To initiate the heartbeat.

• To repolarize the ventricles.

• To delay electrical impulses.

• To conduct impulses to the bundle branches.

How do Purkinje fibers contribute to the heart's function?

• By acting as the heart's natural pacemaker.

• By delaying electrical impulses to the ventricles.

• By spreading impulses throughout the ventricular myocardium.

• By recording the heart's electrical activity.

What does the P wave on an ECG represent?

• Ventricular depolarization.

• Atrial depolarization.

• Ventricular repolarization.

• The delay of electrical impulses at the AV node.

What event does the QRS complex on an ECG mark?

• The firing of the SA node.

• Ventricular relaxation.

• Atrial repolarization.

• The firing of the AV node and ventricular depolarization.

What is the significance of the S-T segment on an ECG?

• It marks the delay of electrical impulses at the AV node.

• It reflects the plateau in the myocardial action potential.

• It indicates the heart's natural pacemaking activity.

• It represents atrial repolarization.

What does the T wave on an ECG indicate?

• The delay of electrical impulses at the AV node.

• Ventricular depolarization.

• Atrial depolarization.

• Ventricular repolarization.