- Atrioventricular node
- The atrioventricular (AV) node is an electrical relay station between the atria (the upper) and the ventricles (the lower chambers of the heart). Electrical signals from the atria must pass through the AV node to reach the ventricles. The AV node is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical impulses and conducts them throughout the muscle of the heart, stimulating the heart to contract and pump blood. The SA node (SA stands for sinoatrial) is the heart's natural pacemaker. The SA node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart).
The electrical impulses are generated there. The SA node is also called the sinus node. The electrical signal generated by the SA node moves from cell to cell down through the heart until it reaches the AV node, a cluster of cells situated in the center of the heart between the atria and ventricles. The AV node serves as a gate (an "electrical relay station") that slows the electrical current before the signal is permitted to pass down through to the ventricles. This delay ensures that the atria have a chance to fully contract before the ventricles are stimulated. After passing the AV node, the electrical current travels to the ventricles along special fibers embedded in the walls of the lower part of the heart. The autonomic nervous system, the same part of the nervous system as controls the blood pressure, controls the firing of the SA node to trigger the start of the cardiac cycle. The autonomic nervous system can transmit a message quickly to the SA node so it in turn can increase the heart rate to twice normal within only 3 to 5 seconds. This quick response is important during exercise when the heart has to increase its beating speed to keep up with the body's increased demand for oxygen.
* * *atrioventricular node n a small mass of tissue that is situated in the wall of the right atrium adjacent to the septum between the atria, passes impulses received from the sinoatrial node to the ventricles by way of the bundle of His, and in some pathological states replaces the sinoatrial node as pacemaker of the heart
* * *(AV node)a mass of modified heart muscle situated in the lower middle part of the right atrium. It receives the impulse to contract from the sinoatrial node, via the atria, and transmits it through the atrioventricular bundle to the ventricles.
* * *AV node (AVN) nodus atrioventricularis.
Medical dictionary. 2011.
Look at other dictionaries:
atrioventricular node — noun a node of specialized heart muscle located in the septal wall of the right atrium; receives impulses from the sinoatrial node and transmits them to atrioventricular bundle • Hypernyms: ↑cardiac muscle, ↑heart muscle * * * noun : a small mass … Useful english dictionary
Atrioventricular node — Infobox Anatomy Name = PAGENAME Latin = nodus atrioventricularis GraySubject = GrayPage = Caption = AV node visible near bend of red line. Caption2 = Heart; conduction system Precursor = System = Artery = atrioventricular nodal branch Vein =… … Wikipedia
atrioventricular node — Anat. a small mass of muscular fibers at the base of the wall between the atria, conducting impulses received from the sinoatrial node by way of the atrioventricular bundles and, under certain conditions, functioning for the sinoatrial node as… … Universalium
atrioventricular node — AV node a mass of modified heart muscle situated in the lower middle part of the right atrium. It receives the impulse to contract from the sinoatrial node, via the atria, and transmits it through the atrioventricular bundle to the ventricles … The new mediacal dictionary
atrioventricular node — noun Date: circa 1934 a small mass of tissue in the right atrioventricular region of higher vertebrates through which impulses from the sinoatrial node are passed to the ventricles … New Collegiate Dictionary
atrioventricular node — a′trioventric′ular node n. anat. a small mass of conducting muscle fibers in the heart, at the base of the right atrium, that transmits heartbeat impulses to the ventricles • Etymology: 1930–35 … From formal English to slang
atrioventricular node — /ætrioʊvɛnˌtrɪkjələ ˈnoʊd/ (say atreeohven.trikyuhluh nohd) noun a mass of specialised conductive tissue in the heart, which transmits electrical impulses to initiate contraction; A V node … Australian English dictionary
Узел Атриовентрикулярный (Atrioventricular Node) — часть проводящей системы сердца; расположен в межпредсердной перегородке. Импульс поступает в него от синусно предсердного узла по кардиомиоцитам предсердий, а затем передается через предсердножелудочковый пучок миокарду желудочков. Источник:… … Медицинские термины
atrioventricular bundle — n BUNDLE OF HIS * * * (AV bundle, bundle of His) a bundle of modified heart muscle fibres (Purkinje fibres) passing from the atrioventricular node forward to the septum between the ventricles, where it divides into right and left bundles, one for … Medical dictionary
Atrioventricular — (having to do with an atrium and ventricle) can refer to: *Left atrioventricular opening *Atrioventricular fistula *Atrioventricular node *The term Atrioventricular valves is used to describe the mitral valve and tricuspid valve … Wikipedia