Expert: Walter Hintz - 7/9/2010

Question
Why  the speed of cardiac impulse in perkinjee fibre is maximum about all the nodes in heart?

Answer
I am not sure what you know about purkinje fibers and the question eludes me. Let me tell the function of these nerve fibers and hen tell me if you got an answer
The impulse from the SA node cannot get directly to the ventricle because there is an insulating layer between the Atria and ventricles.  The impulse from the SA node has to pass through the AV node and has to speed up to the bottom of the ventricle. This speed up is the function of the purkinje system. The impulse must quickly reach the bottom of the ventricle so the ventricle will contract for the bottom up since the blood passes up to leave the ventricles.Otherwis the ventricle would squeeze from the top down trapping blood.