Answer:
The cardiac action potential propagates more slowly in an AV node cell due to its smaller diameter and fewer gap junctions compared to atrial or ventricular myocytes. This reduced speed allows for a delay in electrical signal transmission, ensuring proper coordination of atrial and ventricular contractions. Furthermore, the AV node features a unique conduction pathway involving slower conduction through specialized transitional cells and a lower density of ion channels, resulting in a longer action potential duration and slower propagation.