Which conduction tissue has a conduction velocity of 0.4 m/s?

Which conduction tissue has a conduction velocity of 0.4 m/s?

• A. SA node
• B. AV node
• C. Purkinje fibers
• D. Bundle of His

Answer: (B)

The key idea is that the heart uses different conduction speeds to time the sequence of beating. The AV node is designed to slow the electrical impulse, creating a deliberate delay between atrial contraction and ventricular contraction. This delay lets the atria finish filling the ventricles before the ventricles start to contract, which is crucial for efficient pumping. Among the conduction tissues, the AV node is the slowest pathway, so its conduction velocity is much slower than the Purkinje system, the bundle of His, and the muscle of the atria and ventricles. The Purkinje network conducts very rapidly to ensure the ventricles depolarize quickly and uniformly; the bundle of His is intermediate in speed; the SA node primarily provides rhythmic impulse generation and isn’t chosen for a slow conduction path between atria and ventricles. Therefore, the AV node’s relatively slow velocity makes it the correct tissue for this characteristic.

The key idea is that the heart uses different conduction speeds to time the sequence of beating. The AV node is designed to slow the electrical impulse, creating a deliberate delay between atrial contraction and ventricular contraction. This delay lets the atria finish filling the ventricles before the ventricles start to contract, which is crucial for efficient pumping.

Among the conduction tissues, the AV node is the slowest pathway, so its conduction velocity is much slower than the Purkinje system, the bundle of His, and the muscle of the atria and ventricles. The Purkinje network conducts very rapidly to ensure the ventricles depolarize quickly and uniformly; the bundle of His is intermediate in speed; the SA node primarily provides rhythmic impulse generation and isn’t chosen for a slow conduction path between atria and ventricles. Therefore, the AV node’s relatively slow velocity makes it the correct tissue for this characteristic.