At what structure in the transmission sequence(cardiac cycle) is the impulse temporarily delayed? and why?

Answer 1

AV node

Cos God made it that way - or maybe we evolved that way.

In order to have effective filling of the ventricles, there is a contraction of the atria with a significant atrio-ventricular delay (you wouldn't want the ventricles to fire off in the middle of this filling now would you?). This allows the atria to load up the ventricles just prior to systole.

Answer 2

1. The impulse is delayed at the Atrioventricular node which as the name suggests lies at the point of transmission between the atria and ventricles

2. At the end of atrial systole the last 30% has just been squeezed into the ventricles. The atrioventricular valves are now beginning to close, the atria will then begin to relax and only after the valves have shut should the ventricles begin contracting. If they contract any sooner the blood will be refluxed back into the empty atria.

3. The AV node alows for a delay between the atrial contraction and ventricular contraction during which the atrioventricular valves shut and atrial relaxation can begin before isovolumetric contraction begins

4. Please refer to a good physiology book as my knowledge may lack specific detail

Answer 3

At the AV bundle or the bundle of Hiss- the transmitting zone between the auricles and ventricles.
There is a delay coz the auricular & ventricular walls lack continuity due to their muscle constitution being different.