Atrioventricular Node and Delay of Impulse Conduction from the Atria to the Ventricles

The atrial conductive system is organized so that the cardiac impulse does not travel from the atria into the ventricles too rapidly; this delay allows time for the atria to empty their blood into the ventricles before ventricular contraction begins. It is primarily the A-V node and its adjacent conductive fibers that delay this transmission into the ventricles.

The A-V node is located in the posterior wall of the right atrium immediately behind the tricuspid valve, as shown in Figure 10-1. And Figure 10-3 shows dia-grammatically the different parts of this node, plus its connections with the entering atrial internodal pathway fibers and the exiting A-V bundle. The figure also shows the approximate intervals of time in fractions of a second between initial onset of the cardiac impulse in the sinus node and its subsequent appearance in the A-V nodal system. Note that the impulse, after traveling through the internodal pathways, reaches the A-V node about 0.03 second after its origin in the sinus node. Then there is a delay of another 0.09 second in the A-V node itself before the impulse enters the penetrating portion 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 multiple small fascicles passing 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, in 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.

Cause of the Slow Conduction. The slow conduction in the transitional, nodal, and penetrating A-V bundle fibers is caused mainly by diminished numbers of gap junctions between successive cells in the conducting pathways, so that there is great resistance to conduction of excitatory ions from one conducting fiber to the next. Therefore, it is easy to see why each succeeding cell is slow to be excited.

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Responses

  • Isacco
    What causes the delay in the impulse as it reaches AV?
    3 years ago
  • JORMA HYYPI
    What is the reason for a v nodal delay?
    3 years ago
  • Arja
    Why is there a delay in the av node?
    3 years ago
  • manfredo
    Why is conduction delay at the av node?
    3 years ago
  • Kenneth
    Why there is conduction delay of impulse at av node?
    3 years ago
  • Efisio
    Why is transmission slower within atrioventricular node?
    3 years ago
  • Omar
    Why av nodal delay occurs?
    3 years ago
  • Celedor
    Why there is conduction pause at AV node?
    3 years ago
  • andrew wallace
    Why impulses move slowly in atrioventricular node?
    3 years ago
  • PIA
    What part of conduction system is responsible for delay in impulse transmission?
    3 years ago
  • fethawi
    What is the clinical relevance of Av nodal delay?
    3 years ago
  • Kalimac
    Why is the signal delay between the atria and ventricles necessary?
    3 years ago
  • teemu
    What is advantage atrio ventricular node delay?
    3 years ago
  • Sandra
    Why does the AV node delays impulses?
    2 years ago
  • heike
    Why each successive cell is slow to be excited in internodal pathway?
    2 years ago
  • Lorenzo
    How much delay of impulse conduction occurs at the AV node?
    2 years ago
  • seppo salama
    How long is the delay at the conducting system at the AV node?
    2 years ago
  • TESMI
    Why is there delay in transmission of signal to the ventricles?
    2 years ago
  • nils
    What is delay in AV junction?
    2 years ago
  • JONAS
    Which ion is responsible foe the slowed conduction between atria and ventricles?
    2 years ago
  • Temesgen
    What is the signifigance of delying te impulse at the AVN?
    1 year ago
  • sebastian
    Why is there a delay in the heart before theimulse reaches the bundle of his?
    12 months ago
  • Ilse
    Why does the atrioventricular node delay the passage of electrical impulses to the ventricles?
    11 months ago
  • juuso
    Why dose the atrioventricular node delay passage of electrical impluses to the ventricles?
    11 months ago
  • ambessa
    Does labetalol slow conduction to av node?
    10 months ago
  • Russom
    Why does the AntrioVentricular (AV) Node pause the conduction signal for a moment?
    10 months ago
  • Lisa
    Why does a slight delay in impulse transmission occur at the atrioventricular node?
    10 months ago
  • simone
    Why there is delay in AV node to Av bundle?
    9 months ago
  • fedra
    When does the av nodal delay occur?
    9 months ago
  • Philipp
    What is the normal atrioventricular delay?
    8 months ago
  • florian
    When does cardiac impulse delayed?
    8 months ago
  • dina
    How long is the delay of impulse between the atria and ventricles?
    8 months ago
  • gerardino
    How long is the delay of impulse conduction between atria and ventricle?
    8 months ago
  • Michelina Cattaneo
    Why does the av bundle delay transmission?
    7 months ago
  • alexander fegan
    How does ach delay electrical impulse at AV?
    7 months ago
  • taylor
    Why is there a delay in the conduction system heart?
    6 months ago
  • Katariina
    Does delay occur in internodal pathways?
    6 months ago
  • zemzem
    Why does AVN delay decrease?
    6 months ago
  • ALBERT
    What is the normal total delay of the cardiac impulse in the av node and the av bundle system?
    6 months ago
  • bryan
    Do frogs have av nodal delay?
    6 months ago
  • mackenzie
    Why does conduction slow at bundle of his?
    5 months ago
  • gloria
    How long does av nodes delay impulses?
    5 months ago
  • REMIGIO SICILIANO
    What causes delay of impi;se cpmdictopm at the AV node?
    5 months ago
  • settimio
    Why is it important for ap to be delayed at the avn?
    4 months ago
  • claudia
    Why is there a slight delay before the atrioventricular valve closes?
    4 months ago
  • sophie kuester
    Why are signals delayed at av node?
    4 months ago
  • giona
    Why impulse delayed at av node?
    3 months ago
  • pekka
    Why is the conduction impulse paused at the AV Node?
    3 months ago
  • PHILIP
    What causes the delay of transmission of the depolarization from the atria to the ventricles?
    3 months ago
  • Raakel
    Which of the following receives a conductive impulse after the av node?
    3 months ago
  • faruz
    What slows sa node transmission between atria?
    2 months ago
  • Petra
    Why is the delay of the av node important?
    2 months ago
  • sophia
    What are the electrical impulses delayed at the av node?
    2 months ago
  • Alem
    Which of the following reflects the delay between the av node and the bundle of his.?
    2 months ago
  • temesgen berhane
    When impulse reaches the av node it slows before going to the?
    1 month ago
  • MEZAN
    What is the significance of delaying the impulse at the avn?
    19 days ago
  • berhane
    Which reflect the delay between the AV node and the Bundle of His?
    10 days ago

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