Final answer:
Action potentials do pass slowly through the atrioventricular node, creating a deliberate 100 ms delay in the heart's conduction system, which allows the atria to complete contraction before the impulse travels to the ventricles.
Step-by-step explanation:
Yes, action potentials pass slowly through the atrioventricular (AV) node in the heart's conduction system. The AV node is a cluster of specialized myocardial conductive cells found in the right atrium. This structure is responsible for creating a deliberate delay in the electrical conduction from the atria to the ventricles. The reasons for this delay include the smaller diameter of the nodal cells and less efficient electrical conduction compared to other conducting cells in the heart.
The pause at the AV node is approximately 100 milliseconds (ms), which is crucial for cardiac function, as it allows the atria to complete the contraction and pump blood into the ventricles before the impulse is transmitted to the ventricular myocardium. The AV node can transmit impulses at a maximum rate of 220 per minute under extreme stimulation by the SA node.
In comparison to other parts of the cardiac conduction system, the AV node does have a slower inherent rate of firing, and the bundle branches and Purkinje fibers can fire at even slower rates if there is a blockage or absence of the upstream pathways.