This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Normal AV delay of 0.1 seconds is due to 
Select and explain. 
A. Decrease in amplitude of firing, B. Resistance offered by myocytes, C. Decrease in number of gap junctions, D. Lack of tight junctions
C: Decrease in number of gap junctions
Answer: C: Decrease in number of gap junctions 
Explanation: AV nodal fibers are small and have lesser gap junctions. This leads to AV nodal delay and slower conduction speed.