The atrioventricular node (abbreviated AV node) is an area of specialized tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse
from the atria to the ventricles.
The AV node may also be (rarely) referred to as the Aschoff-Tawara node.[1]
Function
The AV node receives two inputs from the atria: posteriorly via the crista
terminalis, and anteriorly via the interatrial septum.[2]
An important property that is unique to the AV node is decremental conduction, in which the more frequently the node is
stimulated, the slower it conducts. This is the property of the AV node that prevents rapid conduction to the ventricle in cases
of rapid atrial rhythms, such as atrial fibrillation or atrial flutter.
The atrioventricular node delays impulses for ~0.1 second before allowing impulses through to the His-Purkinje conduction
system, which spreads impulses to the ventricular walls. The reason it is important to delay the cardiac impulse is to ensure
that the atria have ejected their blood into the ventricles before the ventricles contract.[3]
Blood supply
The blood supply of the AV node is from a branch of the right coronary artery
in 85% to 90% of individuals, and from a branch of the left
circumflex artery in 10% to 15% of individuals. When the RCA supplies the AV node, the coronary system is said to be
"right dominant," and when the AV node is supplied by the LCX, the system is "left dominant."
See also
References
- ^ synd/454 at Who Named It
- ^ ACC/AHA/ESC Guidelines for the Management of Patients with Atrial
Fibrillation - Executive Summary (Full text)
- ^ Campbell, N., & Reece, J. (2002). Biology. 6th ed. San Francisco:
Benjamin Cummings.
External links
|
Anatomy of torso,
cardiovascular system: heart |
| Structures |
atria (interatrial septum, musculi pectinati) • ventricles (interventricular septum, trabeculae carneae,
chordae tendinae, papillary muscle) • valves • cusps |
| Regions |
base • apex • grooves (coronary/atrioventricular, interatrial, anterior interventricula, posterior
interventricular) • surfaces (sternocostal, diaphragmatic) • borders (right,
left) |
| Right
heart |
(vena cavae, coronary sinus) →
right atrium (auricle,
fossa ovalis, limbus of fossa
ovalis, crista terminalis, valve of the inferior vena cava, valve of
the coronary sinus) → tricuspid valve → right ventricle (conus arteriosus, moderator band/septomarginal trabecula) → pulmonary valve → (pulmonary
artery and pulmonary circulation) |
| Left
heart |
(pulmonary veins) → left atrium (auricle) → mitral valve → left ventricle → aortic valve (aortic sinus) → (aorta and systemic circulation) |
| Layers |
pericardium
(sinus) • epicardium • myocardium • endocardium • cardiac skeleton (fibrous trigone, fibrous rings) |
| Conduction system |
Cardiac
pacemaker • SA node • AV node• bundle of His • Purkinje fibers |
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