Cardiac Conduction System and ECG Basics

Flashcards cover the cardiac conduction pathway (SA node to Purkinje fibers), key ECG waves (P, QRS, T), AV node delay, and the resulting ventricular contraction.

What is the pacemaker of the heart?

The SA node (sinoatrial node) initiates the cardiac impulse.

What happens after the SA node fires in terms of atrial activity?

Impulse spreads through atrial muscle fibers causing atrial depolarization and atrial contraction.

What is the function of the atrioventricular (AV) node?

Delays conduction slightly to allow atria to finish contracting before the ventricles begin.

Where is the Bundle of His located and what does it do?

Carries the impulse into the interventricular septum.

What do the right and left bundle branches do?

Carry the impulse down the interventricular septum toward the apex.

What are Purkinje fibers responsible for?

Rapidly conduct the impulse from the bundle branches to the ventricular walls, causing ventricular contraction.

What does the P wave represent on an ECG?

Atrial depolarization spreading through the atrial contractile fibers from the SA node.

What does the QRS complex represent on an ECG?

Ventricular depolarization as the ventricular contractile fibers depolarize.

What does the T wave represent on an ECG?

Ventricular repolarization.

What is the sequence that leads to ventricular contraction after AV delay?

AV node delay followed by conduction through the Bundle of His, bundle branches, and Purkinje fibers to ventricles.

What anatomical structure connects the atria to the ventricles and helps coordinate timing?

The atrioventricular (AV) node in the septal area.

What is the end result of the conduction system activating the ventricles?

Ventricles contract and push blood toward the semilunar valves.