Which structure delays electrical impulses to coordinate atrial and ventricular contraction?

Which structure delays electrical impulses to coordinate atrial and ventricular contraction?

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

Answer: (D)

The delay in coordinating atrial and ventricular contraction occurs at the AV node. After the impulse starts in the atria, it travels to the AV node, which slows conduction significantly. This brief pause lets the atria finish contracting and filling the ventricles before the signal moves on to the ventricles for a synchronized, strong contraction. The AV node’s slow conduction is what creates that essential delay, while the SA node sets the beat as the natural pacemaker and the Purkinje fibers along with the Bundle of His rapidly propagate the impulse to the ventricles for quick, coordinated contraction.

The delay in coordinating atrial and ventricular contraction occurs at the AV node. After the impulse starts in the atria, it travels to the AV node, which slows conduction significantly. This brief pause lets the atria finish contracting and filling the ventricles before the signal moves on to the ventricles for a synchronized, strong contraction. The AV node’s slow conduction is what creates that essential delay, while the SA node sets the beat as the natural pacemaker and the Purkinje fibers along with the Bundle of His rapidly propagate the impulse to the ventricles for quick, coordinated contraction.