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1
The Basics
This physiologic delay in conduction is essential to allow the atria
to finish contracting before the ventricles begin to contract. This
clever electrical wiring of the heart permits the atria to empty their
volume of blood completely into the ventricles before the ventricles
contract.
Like the sinus node, the AV node is also under the influence of
the autonomic nervous system. Vagal stimulation slows the current
even further, prolonging the delay, whereas sympathetic stimulation
accelerates the current through the AV node.
B
A
Conduction pause
at the AV node
AV node
(
A
) The wave of depolarization is briefly held up at the AV node. (
B
)
During this pause, the EKG falls silent; there is no detectable electrical
activity.