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26 Cards in this Set
- Front
- Back
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Location of the SA Node
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Upper posterior portion of the Right atrial wall of the heart, near the opening of the superior vena cava.
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Function of the SA Node
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Primary pacemaker of the heart because it normally depolarizes most rapidly.
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Normal Firing range of the SA node
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60-100 beats per minute
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Location of the Internodal pathways
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between the SA node and the AV junction.
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The internodal pathways consist of how many bands of conduction cells and where do they branch to?
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3 bands of conduction cells; branch throughout the atria
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Function of the Internodal pathways
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3 tracts that receive the electrical impulses as they leave the SA node. They distribute the electrical impulses throughout the atria and transmit the impulse from the SA node to the AV node.
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Location of Bachmann's Bundle:
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Contained in the Left atrium, it is a subdivision of the anterior internodal tract and it is a group of interatrial fibers.
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Function of Bachmann's Bundle:
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conducts electrical activity from the SA node to the Left atrium.
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Location of AV node:
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On the floor of the Right atrium just above the tricuspid valve. Located at the junction between the atria and the ventricles in the right portion of the interatrial septum, posteriorly.
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Function of the AV node:
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Delays electrical activity for approximately 0.05 second, this delay allows for atrial contraction and a more complete filling of the ventricles.
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Location of the AV junction:
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the region where the SA node joins the Bundle of His.
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Function of the AV junction:
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Similar to the SA node, AV junctional tissue contains fibers that can spontaneously depolarize and form electrical impulse that can be spread to the heart chambers- IF SA NODE FAILS OR SLOWS BELOW ITS NORMAL RANGE, THE AV JUNCTIONAL TISSUES CAN INITIATE ELECTRICAL ACTIVITY AND ASSUME THE ROLE OF A SECONDARY PACEMAKER.
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Location of the Bundle of His:
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Leads out of the AV node, is approx 15 mm's long. Lies at the top of the interventricular septum.
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Function of the Bundle of His:
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Have the ability to self-initiate electrical activity.
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Firing rate of Bundle of His/AV node:
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40-60 beats per minute
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Location of the origin of the Bundle Branches:
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Divide into 2 main sections at the top of the interventricular septum, the Right and Left Bundle branches.
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Location of the Right Bundle Branch:
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lyes beneath the endocardium; runs down the right side of the interventricular septum and terminates at the papillary muscles in the right ventricle.
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Location of the Left Bundle Branch:
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shorter than the RBB; the LBB divides into pathways that spread from the Left side of the interventricular septum and throughout the left ventricle.
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What are the 2 main divisions of the Left Bundle Branch Called?
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Fascicles
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Functions of the bundle branches:
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conduct electrical activity from the bundle of his down to the purkinje network.
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Where does the anterior fascicle carry electrical impulses to?
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the anterior wall of the left ventricle
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Where does the posterior fascicle carry electrical impulses to?
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the posterior ventricular wall of the left ventricle.
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What is the location of the purkinje's netowrk?
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the ventricles of the myocardium
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What is the function of the purkine's network?
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carry electrical impulses directly to ventricular muscle cells. Ventricular contraction is facilitated by the rapid spread of electrical impulses throughout the Left and Right Bundle Branches and purkinje fibers into the ventricular muscle.
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What is the normal firing range of the purkinge's network?
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20-40 Beats per minute.
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Explain the normal path of the heart's electrical conduction system start to finish for one beat.
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SA node produces an electrical signal --> signal spreads through the Left and Right Atria --> signal causes the atria to contract --> electrical signal reaches AV node where it pauses briefly, allowing for atrial contraction and more complete filling of the ventricles --> continues through the bundle of his and to the Left and Right Ventricles via the bundle branches --> continues all the way to the purkinje fibers --> this signal causes the ventricles to contract --> blood is then pumped out to your lungs and body
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