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An impulse (action potential) that originates from the SA node at a relative rate of 60–100 bpm is known as a normal sinus rhythm. If SA nodal impulses occur at a rate less than 60 bpm, the heart rhythm is known as sinus bradycardia. If SA nodal impulses occur at a rate exceeding 100 bpm, the consequent rapid heart rate is sinus tachycardia ...
This rate can be altered, however, by nerves that work to either increase heart rate (sympathetic nerves) or decrease it (parasympathetic nerves), as the body's oxygen demands change. Ultimately, muscle contraction revolves around a charged atom (ion) , calcium (Ca 2+ ) , [ 3 ] which is responsible for converting the electrical energy of the ...
The bundle of His (BH) [1]: 58 or His bundle (HB) [1]: 232 (/ h ɪ s / "hiss" [2]) is a collection of heart muscle cells specialized for electrical conduction.As part of the electrical conduction system of the heart, it transmits the electrical impulses from the atrioventricular node (located between the atria and the ventricles) to the point of the apex of the fascicular branches via the ...
The bundle branches were separately described by Retzer and Braeunig as early as 1904, but their physiological function remained unclear and their role in the electrical conduction system of the heart remained unknown until Sunao Tawara published his monograph on Das Reizleitungssystem des Säugetierherzens (English: The Conduction System of the Mammalian Heart) in 1906. [4]
Regardless of the pathway, as the impulse reaches the atrioventricular septum, the connective tissue of the cardiac skeleton prevents the impulse from spreading into the myocardial cells in the ventricles except at the atrioventricular node. [1] The electrical event, the wave of depolarization, is the trigger for muscular contraction.
In the heart's conduction system electrical activity that originates from the sinoatrial node (SAN) is propagated via the His-Purkinje network, the fastest conduction pathway within the heart. The electrical signal travels from the sinoatrial node, which stimulates the atria to contract, to the atrioventricular node (AVN), which slows down ...
the first "pathway" has a slow conduction velocity but shorter refractory period; the second "pathway" has a faster conduction velocity but longer refractory period. [11] An important property that is unique to the AV node is decremental conduction, [12] in which the more frequently the node is stimulated the slower it conducts.
Bachmann's bundle receives its blood supply from the sinoatrial nodal artery (right, left or both). [4]Besides Bachmann's bundle, the other three conduction tracts that constitute the atrial conduction system are known as the anterior, middle, and posterior tracts, which run from the sinoatrial node to the atrioventricular node, converging in the region near the coronary sinus.