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Topic: SA node

Related Topics

Sinoatrial node

Electrical conduction system of the heart

First degree heart block

Mobitz I

Cardiac arrhythmia

Cardiology

Bradycardia

Heart

EKG

Burbot

Handloading

Procell

Marassa

Bhaisajyaguru

Phronesis

	Sinoatrial node - Wikipedia, the free encyclopedia
		The sinoatrial node (abbreviated SA node or SAN, also called the sinus node) is the impulse generating (pacemaker) tissue located in the right atrium of the heart.
		The SA node is richly innervated by vagal and sympathetic fibers.
		In the majority of patients, the SA node receives blood from the right coronary artery, meaning that a myocardial infarction occluding it will cause ischaemia in the SA node unless there is a sufficiently good anastomosis from the left coronary artery.
	en.wikipedia.org /wiki/Sinoatrial_node (481 words)

	The Sinoatrial Node
		The depolarization and repolarization of the SA node and the other elements of the heart's electical system produces a strong pattern of voltage change which can be measured with electrodes on the skin.
		The circuit involves a capacitor which is charged by the energy of a battery(roles played by the membranes of the SA node and the ion transport processes which repolarize it) and a resistor which controls the rate of flashing of the light.
		In the case of the SA node, there is input frorm the physiology of the body related to oxygen demand and other factors which control the rate of firing of the SA node and therefore the heartrate.
	hyperphysics.phy-astr.gsu.edu /hbase/biology/sanode.html (278 words)

	Heart - MSN Encarta
		Cells in the SA node generate their electrical signals more frequently than cells elsewhere in the heart, so the electrical signals generated by the SA node synchronize the electrical signals traveling to the rest of the heart.
		Impulses generated by the SA node spread rapidly throughout the atria, so that all the muscle cells of the atria contract virtually in unison.
		The impulses from the SA node are carried across this connective tissue partition by a small bridge of muscle called the atrioventricular conduction system.
	encarta.msn.com /encyclopedia_761572608_3/Heart.html (1946 words)

	Sinus Mechanisms
		Sinus rhythm is the name given to the rhythm reflecting normal electrical activity - that is, the rhythm originates in the SA node and follows the normal pathway of conduction through the atria, AV junction, bundle branches, and ventricles resulting in atrial and ventricular depolarization.
		Thought to occur due to failure of the transitional cells in the SA node to conduct the impulse from the pacemaker cells to the surrounding atrium.
		Rhythmicity of the SA node is unaffected by the SA block, thus impulses are generated regularly.
	mywebpages.comcast.net /tracyvanatta/sinusMechanisms.html (594 words)

	Node, SA definition - Medical Dictionary definitions of popular medical terms
		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 signal generated by the SA node moves from cell to cell down through the heart until it reaches the atrioventricular node (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 that slows the electrical current before the signal is permitted to pass down through to the ventricles.
	www.medterms.com /script/main/art.asp?articlekey=4574 (349 words)

	Glossary of Terms (S)
		If the SA node, the heart's natural pacemaker, loses the ability to initiate a heartbeat or increase the heart rate, the heart may not be able to respond effectively to the body's changing circulation demands.
		In response to sick sinus syndrome, other tissues in the heart often take over the role of the SA node, but at an inconsistent rate or a rate that is too slow or too fast for normal activities.
		SA node disease results in a condition called symptomatic bradycardia, in which the heart beats at less than 60 beats per minute.
	www.medtronic.com /corporate/glossary/s.html (1001 words)

	eMedicine - Sinus Bradycardia : Article Excerpt by: Mark Livingston, MD (Site not responding. Last check: 2007-11-06)
		SA block may be associated with abnormal intrinsic nodal function, a failure of the SA junction, or a failure of propagation in the surrounding tissue.
		First-degree SA block is characterized by a delay in the propagation of the action potential from the SA node to the atria.
		Second-degree SA block is characterized by an occasional dropped P wave (analogous to the dropped QRS complex of second-degree AV block), reflecting the inability of the SA node to consistently transmit an action potential to the surrounding myocardium.
	www.emedicine.com /emerg/byname/sinus-bradycardia.htm (778 words)

	Sinoatrial node Summary
		The S-A node or sino-atrial node (also spelled unhyphenated as the sinoatrial node) is a specialized area of tissue located along the upper margin of the right atrium of the heart that acts to regulate the contractions of the heart.
		The sinoatrial node (SA node) is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava.
		If the SA node doesn't function, or the impulse generated in the SA node is blocked before it travels down the electrical conduction system, a group of cells further down the heart will become the heart's pacemaker.
	www.bookrags.com /Sinoatrial_node (685 words)

	AnatomySAnode
		The SA node is located high on the right atrium close to whether the superior vena cava enters the right atrium.
		A heart controlled by the SA node is said to be in normal sinus rhythm.
		The rhythm originates from the SA node because the SA node depolarizes more frequently (60-100 beats per minute) than the AV node (40-60 beats per minute) and ventricular conducting system (30-40 beats per minute) so the AV node and ventricular conducting system are 'captured' by the sinus impulse and driven at 60-100 beast per minute.
	sprojects.mmi.mcgill.ca /cardiophysio/AnatomySAnode.htm (376 words)

	AV node definition - Medical Dictionary definitions of popular medical terms
		AV node: An electrical relay station between the atria (the upper) and the ventricles (the lower chambers of the heart).
		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.
	www.medterms.com /script/main/art.asp?articlekey=2407 (431 words)

	Gradient Model Versus Mosaic Model of the Sinoatrial Node -- Zhang et al. 103 (4): 584 -- Circulation (Site not responding. Last check: 2007-11-06)
		1% of the area of the SA node and is normally in the center of the SA node.
		SA node: in the periphery of the SA node, g
		Connexin45, a major connexin of the rabbit sinoatrial node, is co-expressed with connexin43 in a restricted zone at the nodal-crista terminalis border.
	circ.ahajournals.org /cgi/content/full/103/4/584 (2933 words)

	Department of Medicine: Cardiology
		If the SA node loses its ability to initiate a heartbeat or increase the heart rate, (sick sinus syndrome) the heart may not be able to respond effectively to the body's changing blood circulation demands.
		The electrical signal from the SA node must pass through the AV node to continue along conduction pathways to cause the ventricles to contract and pump blood out of the heart.
		The electrical signal from the SA node must pass through the AV node and continue on through the conduction pathways in the ventricles.
	www.med.miami.edu /med/cardiology/heartfaq.asp (1627 words)

	Normal heart rhythm
		The SA node consists of specialized cells that undergo spontaneous generation of action potentials at a rate of 100-110 action potentials ("beats") per minute.
		Action potentials generated by the SA node spread throughout the atria, depolarizing this tissue and causing atrial contraction.
		Abnormal cardiac rhythms may occur when the SA node fails to function normally, when other pacemaker sites (e.g., ectopic pacemakers) trigger depolarization, or when normal conduction pathways are not followed.
	www.cvphysiology.com /Arrhythmias/A002.htm (262 words)

	Children's Heart Institute \| How the Heart Works: The Heart Electric System
		The Sinus Node is considered to be the main switch of the heart which inititates the electric impulse of the heart and terminates it.
		The SA Node is also known as the normal heart pacemaker, as it sets the pace of the heartbeat.
		The AV Node is responsible for transmitting the impulse from the atria to the ventricles.
	www.childrensheartinstitute.org /educate/heartwrk/elechhse.htm (1693 words)

	Automatic External Defibrillators
		The SA node depolarizes and all the cells touching the SA node are "excited" into depolarizing, which in turn, excites all the cells touching those cells to also depolarize, yatta., yatta, yatta.
		The SA node starts all normal "beats" because it becomes excited (and depolarizes) faster than any other cardiac cell (usually between 60 and 100 times a minute.) Therefore, "Normal Sinus Rhythm" is a cardiac rate between 60 and 100 that originates from the Sinoatrial Node.
		A part of the atrioventricular node, called the AV Junction is capable of starting a depolarization wave, but its intrinsic rate is about 40 to 60 beats a minute and, again, under normal circumstances the SA node has the AV node running faster than its (AV node) intrinsic rate.
	www.emergencymedicaled.com /215AED.htm (2673 words)

	The Cardiac Cycle
		The specialised cardiac muscle of the SA node is characterised by the property of automatic self-excitation and it initiates each beat of the heart.
		Therefore, the SA node is often referred to as the pacemaker of the heart.
		Since the fibres of the SA node fuse with the surrounding atrial muscle fibres, the action potential generated in the nodal tissue spreads throughout both atria at a rate of approximately 0.3 meter per second and produces atrial contraction.
	www.jdaross.cwc.net /cardiac_cycle.htm (1160 words)

	South Afican Node
		The SA Node of the Millennium Project (MP) was formed through the facilitation of Jerome C. Glenn, Director of the MP.
		The SA Node is set up in a fairly amorphous way in the sense that it is not rooted in any one institution.
		Once the Node is established and functioning, it is the full intention of the co-chairs to extend activities into the region, beginning with Southern and East Africa where two co-chairs have extensive contacts.
	www.acunu.org /millennium/safrica-05.html (912 words)

	Glossary of Cardiovascular Terms (Site not responding. Last check: 2007-11-06)
		The bundle of His or AV bundle is the part of the Purkinje system that connects directly to the AV node.
		The SA node is the pace maker of the heart.
		In the normal heart, heart rate is under the control of the SA node and is said to be in sinus rhythm.
	lysine.pharm.utah.edu /netpharm/netpharm_00/glossary.html (3588 words)

	Ventricular rhythm
		This is an acute or transient escape from the SA node to emit ONE beat from another foci (atrial, junctional, or ventricular).
		During a sinus rhythm (originating at SA node), a momentary (transient) sinus block makes the SA node miss a cycle; therefore there is a pause and then another foci (perhaps in the atria) will emit an impulse or atrial escape beat.
		The conduction from the atria to the ventricles bypasses the AV node.
	www.unm.edu /~lkravitz/EKG/ventricular.html (542 words)

	Cardiac Dysrhythmias (Site not responding. Last check: 2007-11-06)
		The missing P wave is due to the fact that the SA node is silent and the alternate pacemakers around the SA node are also silent.
		It is absent because the signal did not originate close to the SA node and did not use a conduction pathway of a secondary pacemaker.
		The AV node cannot handle the extraordinary number of atrial impulses bombarding it with the end result that most of the impulses simply are not caught by the AV node.
	jan.ucc.nau.edu /~daa/heartlung/lectures/ekg3.html (3754 words)

	Requirement of neuronal- and cardiac-type sodium channels for murine sinoatrial node pacemaking -- Lei et al. 559 (3): ...
		this presumably corresponds to the periphery of the SA node.
		the SA node on the endocardial surface of the crista terminalis
		to be from the centre of the SA node) and in the region of the
	jp.physoc.org /cgi/content/full/559/3/835 (5618 words)

	Information on atrial fibrillation (abnormality in the heart rhythm) produced by medical doctors
		It is a small patch of cells located in the wall of the right atrium; the frequency with which the SA node discharges determines the rate at which the heart beats.
		The AV node serves as an electrical relay station between the atria and the ventricles.
		At rest, the frequency of the electrical discharges originating from the SA node is low, and the heart beats at the lower range of normal (60-80 beats/minute).
	www.medicinenet.com /atrial_fibrillation/article.htm (1204 words)

	AnatomyAVNode
		It receives impulses from the SA node and conducts them to the bundle of His.
		The electric impulse from the SA must be conducted though the AV node because the atria and ventricles are separated by a fibrous connective tissue septum that has poor conductivity.
		AV node because the atria and ventricles are separated by a fibrous connective tissue ring that has poor conductivity.
	www.technion.ac.il /~eilamp/AnatomyAVnode.html (285 words)

	The EKG Components of the Cardiac Cycle
		The SA Node is commonly referred to as the "Pacemaker" of the heart!
		The AV Node generally slows down the transmission of the signals from the SA Node, however, it has the ability to speed up or generate it's own transmissions.
		If the SA Node Fails to fire, and the AV Node fails to fire, then a response may be initiated by the ventricle(s) it'self.
	www.randylarson.com /acls/cycle.html (988 words)

	Sick Sinus Syndrome
		From the AV node, the signal is conducted along pathways that spread into the ventricles, causing them to contract and pump blood into the lungs and throughout the body.
		Sinus "pauses," or gaps between signals from the SA node, that indicate the heart is not being paced at the normal, steady rate.
		If the SA node stops working or doesn't work properly, another pacemaker at the center of the heart called the AV node may begin signaling the heart to beat.
	www.hrspatients.org /patients/heart_disorders/sick_sinus/default.asp (876 words)

	Sick Sinus Syndrome - Texas Heart Institute Heart Information Center
		The SA node is located at the top of the heart's upper-right chamber (the right atrium).
		The SA node is sometimes called the heart's "natural pacemaker." When an electrical impulse is released from the SA node, it causes the heart's upper chambers to contract.
		The SA node usually sends electrical impulses at a certain rate, but if the SA node is not working properly, the heart may beat too fast, too slow, or both.
	www.texasheartinstitute.org /HIC/Topics/Cond/sicksinus.cfm (827 words)

	Electrical conduction system of the heart - Wikipedia, the free encyclopedia
		The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to (and stimulate) the myocardium (muscle of the heart).
		As the electrical activity is spreading throughout the atria, it travels via specialized pathways, known as internodal tracts, from the SA node to the AV node.
		The distal portion of the AV node is known as the Bundle of His.
	en.wikipedia.org /wiki/Electrical_conduction_system_of_the_heart (475 words)

	Premature Ventricular Contraction Information by MedicineNet.com
		The SA node is the heart's electrical pacemaker.
		It is a small patch of cells located in the wall of the right atrium; the frequency with which the SA node discharges electricity determines the rate at which the heart normally beats.
		The electrical discharges pass from the SA node, through the special tissues of the atria into the AV node, and through the AV node to the special conduction tissues of the ventricles and causing the ventricles to contract.
	www.medicinenet.com /premature_ventricular_contractions/article.htm (495 words)

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