Circulatory system

Where is the sinoatrial (SA) node located and what is its primary function?

• In the left atrium, initiating ventricular contraction.

• In the right atrium near the superior vena cava, initiating heartbeat and determining heart rate.

• In the ventricles, delaying electrical impulses.

• In the interventricular septum, conducting impulses to the apex.

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

• To initiate all heartbeats.

• To spread electrical impulses throughout the atria.

• To delay the passage of electrical impulses to the ventricles.

• To conduct impulses to the Purkinje fibers.

After passing through the AV bundle, where do electrical impulses travel next in the heart's conduction system?

• Directly to the atria.

• To the sinoatrial node.

• To the right and left bundle branches, then Purkinje fibers.

• To the superior vena cava.

What does the QRS complex on an ECG primarily represent?

• Atrial repolarization.

• Ventricular repolarization.

• Ventricular depolarization.

• Atrial contraction.

What event in the heart's electrical cycle is represented by the P wave on an electrocardiogram (ECG)?

• Ventricular repolarization.

• Atrial depolarization.

• Ventricular contraction.

• Delay of signals at the AV node.