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Sinoatrial NodeSinoatrial BlockTachycardia, Sinoatrial Nodal ReentryLymph NodesAtrioventricular NodeBiological ClocksBradycardiaHeart AtriaAction PotentialsHeart RateHeart Conduction SystemRabbitsAtrial FunctionHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsArrhythmia, SinusModels, CardiovascularVagus NerveCyclic Nucleotide-Gated Cation ChannelsElectrophysiologySick Sinus SyndromeImpulse Control DisordersMembrane PotentialsHeart BlockAtrial Function, RightCalcium Channels, L-TypeDogsConnexinsHeartElectrocardiographyPotassium ChannelsCalcium Channels, T-TypeConnexin 43Tachycardia, SinusIon ChannelsIsoproterenolCardiac Pacing, ArtificialMicroelectrodesPatch-Clamp TechniquesMyocytes, CardiacLymph Node ExcisionMyoblasts, CardiacGuinea PigsAminophyllineElectrophysiological PhenomenaDelayed Rectifier Potassium ChannelsAdrenergic beta-AgonistsArrhythmias, CardiacBenzazepinesSodium ChannelsSentinel Lymph Node BiopsyElectric StimulationPacemaker, ArtificialAcetylcholineComputer SimulationCardiac MyosinsAutonomic Nervous SystemCalciumRyanodineAnti-Arrhythmia AgentsCardiotonic AgentsTime FactorsAging, PrematureParasympathetic Nervous SystemTachycardia, SupraventricularSarcoplasmic ReticulumSodium-Calcium ExchangerNatriuretic Peptide, C-TypeAtropineCalcium SignalingElectrophysiologic Techniques, CardiacIon Channel GatingMyocardial ContractionRyanodine Receptor Calcium Release ChannelLymphatic MetastasisPhosphodiesterase 3 Inhibitors4-Aminopyridine
HeartbeatPacemaker cellsTransmits electrical impulsesGeneratesLocated in the right atriumNatural pacemakerAtria to contractAutomaticityAction potentialsPathwaysDepolarizationTissueInitiatesOriginatesPacemakersActivatesAbnormalPurkinjeExcitationAtriumNervePathwaySinus bradycardiaContractionTravelsTachycardiaAtrial FibrillationOccursUpper chambersSends electricalInitiationCalcium influxGeneratorNormalVentricles to contractGeneticConductsInputsCellsFailsReachesMyocardiumPacing of the ventricles
Heartbeat9
  • Individuals with ankyrin-B syndrome may have problems with the sinoatrial (SA) node, which generates the electrical impulses that start each heartbeat. (medlineplus.gov)
  • If the SA node is not functioning properly, the heartbeat can be too slow (bradycardia). (medlineplus.gov)
  • Each heartbeat begins with an impulse from the heart's pacemaker (sinus or sinoatrial node). (merckmanuals.com)
  • They generate electrical impulses that initiate each heartbeat. (merckmanuals.com)
  • This node is called the pacemaker of the heart because it sets the rate of the heartbeat and causes the rest of the heart to contract in its rhythm. (kidshealth.org)
  • In a heart that works normally, the heartbeat begins in the sinoatrial node (SA node). (clevelandclinic.org)
  • For every heartbeat, each cardiac muscle cell receives electrical impulse initiated and propagated from the sinoatrial node for membrane depolarization to trigger calcium influx and additional calcium release from internal stores, that together initiate contraction. (case.edu)
  • san contains pacemaker cells which are responsible for generation of initial electrical impulse during each heartbeat. (icbcongress.com)
  • 7. Where does the normal electrical impulse originate for each heartbeat? (testbank.ltd)
Pacemaker cells3
  • The hearts pacemaker cells are organised into structures including the sinoatrial node (SAN), atrioventricular node (AVN), bundle of His, the right and left bundle branches and Purkinje fibres. (pulsenotes.com)
  • In this review, we will discuss recent discoveries that contextualize the coupled-clock system, first described in isolated SAN cells, into the complex world of SAN tissue: heterogeneous local Ca2+ releases, generated within SAN pacemaker cells and regulated by the other cell types within the SAN cytoarchitecture, variably co-localize and synchronize to give rise to relatively rhythmic impulses that emanate from the SAN to excite the heart. (bvsalud.org)
  • The normal cardiac impulse of the vertebrate heart originates in the pacemaker cells of the sinoatrial node, located in the right atrium. (medscape.com)
Transmits electrical impulses3
  • It transmits electrical impulses in the different direction along the surface of both atria. (electricalvoice.com)
  • These fibres divide into left and right bundle branches, which transmits electrical impulses to the left and right ventricles respectively. (electricalvoice.com)
  • The battery transmits electrical impulses that go through this generator to stimulate the heart to beat. (orlandocvi.com)
Generates3
  • The SAN generates electrical impulses, action potentials, at regular intervals that signal a healthy, resting heart to pump at a rate of 60 to 70 beats per minute. (nih.gov)
  • This node generates electrical impulses at a rate of 60-100 times per minute. (proacls.com)
  • However, it generates impulses at a slower pace-40-60 beats a minute. (proacls.com)
Located in the right atrium2
  • The heart's "spark plug" is an area of specialized heart tissue called the sinoatrial node (SA node), which is located in the right atrium. (health.am)
  • Normally, the electrical activity of the heart is initiated in the sinus or sinoatrial (SA) node, which is located in the right atrium (see Figure 11-2, pg. (testbank.ltd)
Natural pacemaker3
Atria to contract2
  • nbsp;Sinus or sinoatrial (SA) node starts electrical impulse which causes atria to contract, pumping blood into ventricles. (petyourdog.com)
  • The SA node sends electrical signals that cause the atria to contract (pump). (clevelandclinic.org)
Automaticity2
Action potentials1
Pathways2
  • The electrical impulse is conducted through the AV node and wire-like pathways (Purkinje fibers) to the ventricles, signaling the ventricles to contract and pump blood into the lungs and throughout the body. (health.am)
  • Each impulse travels through internodal pathways in the right and left atria and depolarizes the myocardial cells, causing the muscle in the atrium to contract. (proacls.com)
Depolarization1
  • It occurs when the rate of depolarization of the SA node falls below the rate of the AV node . (wikipedia.org)
Tissue9
  • Another option is radiofrequency catheter ablation, which heats and kills the tissue responsible for sending out the erratic impulses. (stanford.edu)
  • 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 impulse then travels into another area of specialized heart tissue called the atrioventricular node (AV node), which is located between the atria and the ventricles. (health.am)
  • The sinus (or sinoatrial) node is a small area of tissue in the wall of the right atrium. (kidshealth.org)
  • The SA node is a small mass of tissue in the atria. (clevelandclinic.org)
  • [ 1 ] The impulse is then conducted through the atrium to the atrioventricular junction from where, after a delay, the electrical signal is propagated to the ventricles along bundles of specialized conduction tissue to the distal Purkinje fibers, which ramify among the contractile myocardium. (medscape.com)
  • The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below). (medscape.com)
  • 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)
Initiates2
Originates1
  • The electrical impulse normally originates in the sinoatrial (SA) node. (mhmedical.com)
Pacemakers2
  • Pacemakers consist of a battery, an impulse generator, and wires that connect the pacemaker to the heart. (merckmanuals.com)
  • In these cases bradycardia therapy aims at restoring a regular sinus rhythm and sufficient heart rate through battery-powered devices (referred to as pacemakers or implantable pulse generators [IPG]) using small electrical impulses delivered through leads directly to the heart in an effort to stimulate heart muscle cells externally, when intrinsic stimulation fails or is unreliable. (biotronik.com)
Activates2
Abnormal6
  • Third-degree atrioventricular (AV) block, also referred to as third-degree heart block or complete heart block (CHB), is an abnormal heart rhythm resulting from a defect in the cardiac conduction system in which there is no conduction through the atrioventricular node (AVN), leading to complete dissociation of the atria and ventricles. (medscape.com)
  • VT is rapid, erratic heart beats, caused by abnormal electrical impulses that are generated somewhere within the ventricles of the heart. (petyourdog.com)
  • Abnormal rhythms (or arrhythmias ) may arise from abnormalities of impulse formation, or impulse conduction (or sometimes both). (vin.com)
  • These abnormal electrical signals can happen when there is an extra pathway between the atria and the ventricles either directly or within the AV node. (clevelandclinic.org)
  • Block within the normal conduction system is the most obvious form of abnormal impulse conduction. (mhmedical.com)
  • Re-entry , the other form of abnormal impulse conduction, is an important mechanism underlying supraventricular tachycardia in infants. (mhmedical.com)
Purkinje3
  • The AV node's impulse travels through the bundle of His and Purkinje fibers in the same way the SA node's impulse does. (proacls.com)
  • If neither the SA or AV node produces impulses properly, the Purkinje fibers will generate the impulse. (proacls.com)
  • [7] [8] In a third-degree heart block , about 61% take place at the bundle branch-Purkinje system, 21% at the AV node, and 15% at the bundle of His. (wikipedia.org)
Excitation1
Atrium7
  • The AV node receives two inputs from the right atrium: posteriorly, via the crista terminalis, and anteriorly, via the interatrial septum. (wikipedia.org)
  • A normal heart contraction begins with an electrical signal from the sinoatrial node, a group of cells in the right atrium. (stanford.edu)
  • Sinoatrial node is present in the right atrium. (electricalvoice.com)
  • The Sinoatrial node (SA node) in the right atrium works like an internal pacemaker. (proacls.com)
  • This is a safety mechanism when a lack of electrical impulse or stimuli from the atrium occurs. (wikipedia.org)
  • 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)
  • This band continues to the left atrium (LA), with the anterior internodal pathway entering the superior margin of the AV node. (medscape.com)
Nerve1
  • The SA node is densely innervated with postganglionic adrenergic and cholinergic nerve terminals. (medscape.com)
Pathway3
  • If electrical signals travel more quickly through the extra (accessory) pathway than they do through the AV node, your heart beats faster than it should. (clevelandclinic.org)
  • The atrioventricular (AV) node, His bundle, and bundle branches provide the only normal pathway for transmission of impulses between the atria and ventricles. (mhmedical.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)
Sinus bradycardia2
  • Abnormalities in impulse formation result in sinus bradycardia and tachycardia, premature atrial and ventricular contractions, and ectopic or automatic rhythms from the atria, AV node, or ventricles. (mhmedical.com)
  • The third, sick sinus syndrome , covers conditions that include severe sinus bradycardia, sinoatrial block , sinus arrest , and bradycardia-tachycardia syndrome ( atrial fibrillation , atrial flutter , and paroxysmal supraventricular tachycardia ). (wikipedia.org)
Contraction1
  • Conduction through the AV node is slowed so that atrial contraction is complete before ventricular contraction occurs. (mhmedical.com)
Travels4
  • Each time the SA node "fires," an electrical impulse is generated that travels through the right and left atria, signaling these chambers to contract and pump blood into the ventricles. (health.am)
  • From the SA node in the atria, an electrical impulse travels to the atrioventricular node (AV node). (proacls.com)
  • 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)
Tachycardia2
  • Atrioventricular nodal re-entry tachycardia, which is caused by a dual AV node physiology and AVNRT can only occur in people with it, however almost half of the population have it, though only a few of them will develop AVNRT at some point in life. (wikipedia.org)
  • These can be caused by multiple connections from the top to the bottom chambers of your heart either directly or through the AV node, resulting in tachycardia. (clevelandclinic.org)
Atrial Fibrillation1
  • 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. (wikipedia.org)
Occurs2
  • Cystic tumour of atrioventricular nodal region (CTAVN) CTAVN is of endodermal origin and occurs exclusively in the area of the AV node, tricuspid valve, and interatrial septum. (wikipedia.org)
  • This occurs only when the electrical impulses are conducted properly through the heart. (orlandocvi.com)
Upper chambers1
  • The problem stems from chaotic electrical impulses in the upper chambers - the atria - of the heart. (stanford.edu)
Sends electrical1
  • A pacemaker is a small device that sends electrical impulses to the cardiac muscle. (orlandocvi.com)
Initiation1
Calcium influx1
  • Electrical activity through the AV node depends, to a significant degree, upon calcium influx through the slow channel. (nih.gov)
Generator2
  • Through a small incision, the impulse generator, which is about the size of a silver dollar, is inserted just under the skin near the collarbone and connected to the wires. (merckmanuals.com)
  • If the SA node, the primary impulse generator, does not work properly, the AV node can send its own impulses instead. (proacls.com)
Normal6
  • The AV node lies at the lower back section of the interatrial septum near the opening of the coronary sinus, and conducts the normal electrical impulse from the atria to the ventricles. (wikipedia.org)
  • The AV node's normal intrinsic firing rate without stimulation (such as that from the SA node) is 40-60 times/minute. (wikipedia.org)
  • The heart rate, normal, slow, or fast, impulse formation may originate in pace-making cells in the sinoatrial (SA) node or ectopically [ 7 , 8 ]. (hindawi.com)
  • Normal sinus rhythm is usually not affected, but in patients with sick sinus syndrome, verapamil hydrochloride may interfere with sinus-node impulse generation and may induce sinus arrest or sinoatrial block. (nih.gov)
  • The pacemaker acts by mimicking the Sinoatrial node, generating a normal heart rate and rhythm. (orlandocvi.com)
  • An AV-junctional escape complex is a normal response that may result from excessive vagal tone on the SA node. (wikipedia.org)
Ventricles to contract2
  • Electrical impulse moves through the atrioventricular (AV) node and into the ventricles, causing the ventricles to contract and to pump blood to the lungs (right ventricle) and the body (left ventricle). (petyourdog.com)
  • The AV node carries the electrical impulses that tell the ventricles to contract. (clevelandclinic.org)
Genetic1
Conducts2
  • 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. (wikipedia.org)
  • The AVN then conducts the impulse to the His bundle. (medscape.com)
Inputs1
Cells2
Fails2
  • If the SA node fails to depolarize, the AV node can function as an escape pacemaker. (mhmedical.com)
  • [6] This is a protective mechanism for the heart, to compensate for an SA node that is no longer handling the pacemaking activity and is one of a series of backup sites that can take over pacemaker function when the SA node fails to do so. (wikipedia.org)
Reaches1
  • Once the electrical impulse reaches the AV node, it is delayed for approximately 0.1 second before it passes on into the bundle of His. (testbank.ltd)
Myocardium1
  • Autopsy examination revealed diffuse inflammation within his heart muscle (myocardium), and particularly in the hearts unique cardiac impulse conduction system (around the sinoatrial and atrioventricular nodes). (andrewbostom.org)
Pacing of the ventricles1
  • This property is important because loss of the conduction system before the AV node should still result in pacing of the ventricles by the slower pacemaking ability of the AV node. (wikipedia.org)