Which statement correctly ranks conduction velocities from fastest to slowest among Purkinje fibers, AV node, atrial myocardium, and ventricular myocardium?

Which statement correctly ranks conduction velocities from fastest to slowest among Purkinje fibers, AV node, atrial myocardium, and ventricular myocardium?

• A. AV Node fastest, Purkinje slowest
• B. Purkinje fastest, AV Node slowest
• C. Atrial Myocardium fastest, Purkinje intermediate
• D. Ventricular Myocardium fastest, Atrial slowest

Answer: (B)

The thing this item tests is how slow or fast electrical impulses travel through different parts of the heart. Purkinje fibers are built for speed—they’re large in diameter with lots of electrical connections, so impulses race through them quickly. The AV node, on the other hand, is designed to slow things down to give the atria time to contract and fill the ventricles, so it has the slowest conduction. The atrial and ventricular myocardium fall in between, with atrial tissue conducting faster than ventricular tissue due to differences in cell coupling and tissue organization. So the best statement is that Purkinje fibers conduct the fastest and the AV node conducts the slowest, which matches the physiological roles of these pathways.

The thing this item tests is how slow or fast electrical impulses travel through different parts of the heart. Purkinje fibers are built for speed—they’re large in diameter with lots of electrical connections, so impulses race through them quickly. The AV node, on the other hand, is designed to slow things down to give the atria time to contract and fill the ventricles, so it has the slowest conduction. The atrial and ventricular myocardium fall in between, with atrial tissue conducting faster than ventricular tissue due to differences in cell coupling and tissue organization.

So the best statement is that Purkinje fibers conduct the fastest and the AV node conducts the slowest, which matches the physiological roles of these pathways.