Question

Conduction through which of the following is slow to allow atria to contract before the ventricles?

A) atria
B) SA node
C) AV node
D) bundle of His
E) Purkinje fibers

Answer 1

The atrioventricular node (AV node) has the slowest rate of firing in the heart conduction system, allowing the atria to complete their contraction before the ventricles.

Step-by-step explanation:

The atrioventricular node (AV node) is the component of the heart conduction system that has the slowest rate of firing. After the action potential is initiated by the sinoatrial (SA) node, it sweeps across the atria and reaches the AV node.

There is a delay of approximately 100 ms at the AV node, allowing the atria to complete their contraction before the impulse is transmitted to the ventricles through the atrioventricular (AV) bundle and the bundle branches to the Purkinje fibers.