The normal AV nodal delay is: (A) 0.16 sec, (B) 0.13 sec, (C) 0.09 sec, (D) 0.03 sec
Answer is C. There is a delay of another 0.09 second in the A-V node itself before the impulse enters the penetrating poion of the A-V bundle, where it passes into the ventricles. A final delay of another 0.04 second occurs mainly in this penetrating A-V bundle, which is composed of multiplemallasciclesassing through the fibrous tissue separating the atria from the ventricles. Thus, the total delay in the A-V nodal and A-V bundle system is about 0.13 second. This delay, in q addition to the initial conduction delay of 0.03 second from the sinus node to the A-V node, makes a total delay of 0.16 second before the excitatory signal finally reaches the contracting muscle of the ventricles.Ref: Guyton and Hall textbook of medical physiology 13th edition. Page:125