Atrioventricular (AVN) and sinoatrial (SAN) nodes were retrospectively delineated according to published guidelines on the simulation computed tomography scans of 12 breast cancer patients having undergone conserving surgery and adjuvant locoregional volumetric modulated arc therapy. (allenpress.com)
The compact portion of the atrioventricular (AV) node is a superficial structure located just beneath the RA endocardium, anterior to the ostium of the coronary sinus, and directly above the insertion of the septal leaflet of the tricuspid valve. (medscape.com)
The slow-conducting SA and AV nodes take developmental origin from the slow-conducting embryonic inflow tract and atrioventricular canal region. (medscape.com)
Right atrium3
Node of specialized tissue lying near the bottom of the right atrium that fires an electrical impulse across the ventricles, causing them to contract. (encyclopedia.com)
The SA node is located less than 1 mm from the epicardial surface, laterally in the right atrial sulcus terminalis at the junction of the anteromedial aspect of the superior vena cava (SVC) and the right atrium (RA). (medscape.com)
The normal cardiac impulse of the vertebrate heart originates in the pacemaker cells of the sinoatrial node, located in the right atrium. (medscape.com)
Tissue2
The sinoatrial (SA) node is a spindle-shaped structure composed of a fibrous tissue matrix with closely packed cells. (medscape.com)
The human SA node contains a more than 3-fold greater density of beta-adrenergic and muscarinic cholinergic receptors than the adjacent atrial tissue. (medscape.com)
Atrioventricular6
The compact portion of the atrioventricular (AV) node is a superficial structure located just beneath the RA endocardium, anterior to the ostium of the coronary sinus, and directly above the insertion of the septal leaflet of the tricuspid valve. (medscape.com)
At the same time, it depolarizes the atrioventricular (AV) node. (socratic.org)
From the AV node, a tract of conducting fibers called the atrioventricular bundle or bundle of His runs through the cardiac muscle to the top of the interventricular septum. (socratic.org)
Here, we demonstrate that circadian clocks within the brain and heart set daily rhythms in sinoatrial (SA) and atrioventricular (AV) node activity, and impose a time-of-day dependent susceptibility to ventricular arrhythmia. (nih.gov)
Critically, the balance of circadian inputs from the autonomic nervous system and cardiomyocyte clock to the SA and AV nodes differ, and this renders the cardiac conduction system sensitive to decoupling during abrupt shifts in behavioural routine and sleep-wake timing. (nih.gov)
Tissues2
The current passes from the SA node, through the special tissues of the atria, and into the AV node . (medicinenet.com)
The same discharges then pass through the AV node to reach the ventricles, traveling through the special tissues of the ventricles and causing the ventricles to contract. (medicinenet.com)
Tract2
The middle internodal tract begins at the superior and posterior margins of the sinus node, travels behind the SVC to the crest of the interatrial septum, and descends in the interatrial septum to the superior margin of the AV node. (medscape.com)
The posterior internodal tract starts at the posterior margin of the sinus node and travels posteriorly around the SVC and along the crista terminalis to the eustachian ridge and then into the interatrial septum above the coronary sinus, where it joins the posterior portion of the AV node. (medscape.com)
Atria5
Once an impulse is initiated by the SA node, the impulse spreads out over both atria, causing them to contract simultaneously. (socratic.org)
The AV node serves as a relay station between the atria and the ventricles. (medicinenet.com)
Signals from the atria must pass through the AV node to reach the ventricles. (medicinenet.com)
The electrical discharges from the SA node causing the atria to contract and pump blood into the ventricles. (medicinenet.com)
The rapid and irregular discharges from the atria then pass through the AV node and into the ventricles, causing the ventricles to contract irregularly and (usually) rapidly. (medicinenet.com)
The anterior internodal pathway begins at the anterior margin of the SA node and curves anteriorly around the SVC to enter the anterior interatrial band, called the Bachmann bundle (see the image below). (medscape.com)
Neurotransmitters modulate the SA node discharge rate by stimulation of beta-adrenergic and muscarinic receptors. (medscape.com)
the frequency with which the SA node discharges determines the rate at which the heartbeats. (medicinenet.com)
During exercise or excitement, the frequency of discharges from the SA node increases, increasing the rate in individuals who are in good clinical health. (medicinenet.com)
Superior1
This band continues to the left atrium (LA), with the anterior internodal pathway entering the superior margin of the AV node. (medscape.com)
Lower1
At rest, the frequency of the discharges originating from the SA node is low, and the heartbeats at the lower range of normal (60 to 80 beats/minute). (medicinenet.com)