In the electrical conduction system of the heart, which sequence correctly describes the pathway that carries cardiac impulses from initiation to ventricular conduction?

• A. Atrioventricular (AV) node → sinoatrial (SA) node → Purkinje fibers → atrioventricular (AV) bundle (bundle of His) → bundle branches
• B. Sinoatrial (SA) node → atrioventricular (AV) node → atrioventricular (AV) bundle (bundle of His) → right and left bundle branches → Purkinje fibers
• C. Purkinje fibers → bundle branches → atrioventricular (AV) bundle (bundle of His) → atrioventricular (AV) node → sinoatrial (SA) node
• D. Sinoatrial (SA) node → Purkinje fibers → atrioventricular (AV) node → bundle branches → atrioventricular (AV) bundle (bundle of His)

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the role of the sinoatrial (SA) node as the natural pacemaker of the heart, where the electrical impulse originates to initiate the heartbeat.
2. Step 2: Recognize that the impulse travels from the SA node to the atrioventricular (AV) node, which acts as a gatekeeper to delay the signal, allowing the atria to contract before the ventricles.
3. Step 3: Identify that from the AV node, the impulse moves to the atrioventricular (AV) bundle, also known as the bundle of His, which is the only electrical connection between the atria and ventricles.
4. Step 4: Follow the pathway as the impulse travels down the right and left bundle branches, which conduct the signal through the interventricular septum toward the apex of the heart.
5. Step 5: Finally, the impulse reaches the Purkinje fibers, which distribute the electrical signal throughout the ventricular myocardium, causing the ventricles to contract and pump blood.