Identifying the atrioventricular node in the heart diagram

Steps:

• Recall the AV node is part of the heart's electrical conduction system, located in the right atrium near the tricuspid valve.
• Examine the diagram for structures between atria and ventricles, focusing on the interatrial septum.
• Identify the node as a small cluster of cells where the signal from the SA node delays before entering ventricles.
• Match the labeled position to the standard anatomical location of the AV node.

Why B is correct:

• The AV node is defined as the junctional tissue in the lower right atrium that conducts impulses to the bundle of His, matching position B on the diagram.

Why the others are wrong:

• A identifies the sinoatrial node, the heart's primary pacemaker in the upper right atrium.
• C marks the bundle of His, which carries signals through the septum to ventricles.
• D points to the Purkinje fibers, which distribute impulses in ventricular walls.

Final answer: B