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26 Cards in this Set
- Front
- Back
In general, what are the contractions of the heart made possible by?
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properties of cardiac muscle tissue and by specialized cells in the heart, known as its conducting system.
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What is meant by the heart exhibits auto/intrinsic rhythmicity?
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The heart itself (not external nerves) is responsible for initiating the heartbeat.
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What is the term used for how the heart itself is responsible for initiating the heartbeat?
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auto or intrinsic rhythmicity
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Certain cardiac muscle fibers are specialized to do what so the heart will contract, and what are they collectively called?
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Conduct muscle impulses to the contractile muscle cells of the myocardium. Collectively, the cells are part of the heart's conducting system
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What initiates the heartbeat?
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By the cardiac fibers of the sinoatrial (SA) node
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Where is the SA node located?
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posterior wall of the right atrium, adjacent to the entrance of the superior vena cava.
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What is located at the psoterior wall of the right atrium, adjacent to the entrance of the superior vena cava?
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sinoatrial node
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What do the fibers of the SA node act as?
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pacemaker, the rhythmic center that establishes the pace for cardiac activity.
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under the influence of which component of the nervous system do SA node fibers initiate impulses?
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parasympathetic autonomic motor division
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From the SA node the muscle impulses travel through what to cause contraction?
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through both atria
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How does a muscle impulse travel from the sinatrial node to the av node?
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Through cardiac muscle of both atria to cause contraction (atrial systole) and then, via an internodal conduction pathway through the fibrous skeleton, to he atrioventricular AV node
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Through which pathway does the SA node send muscle impulses to cause contraction to, and what contracts?
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internodal conduction pathway, BOTH atria contract
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Where is the AV node located?
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in the floor of the right atrium between the right AV valve and the coronary sinus.
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What prevents random nerve impulses from spreading between the atria and the ventricles?
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Fibrous skeleton
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It is only through which opening in the fibrous skeleton that muscle impulse can spread from the SA node to the AV node?
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internodal conduction pathway
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What happens to the conduction of the impulse as it travels from the atria to the ventricles, and what does this do?
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Slows conduction , providing a delay between activation and contraction of the upper and lower chambers.
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Why is a delay between activation and contraction of the upper and lower chambers important when the muscular impulse reaches the AV node?
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It allows the atria to contract first, the ventricles fill and then contract to push blood out.
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When a heart transplant is done, what important characteristic does that heart have to allow this surgery to be possible?
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intrinsic rhythmicity or autorhythmicity
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After the muscle impulse goes from the SA node through the internodal conduction pathway to the AV node where does it go?
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atrioventricular bundle AV bundle also called the Bundle of His
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What extends into the interventricular septum and then divides into one right branch and 2 left branches?
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The bundle of His
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How does the bundle of His divide?
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one right bundle branch and 2 left bundle branches
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The bundle branches conduct the impulse to conduction fibers called...? Where do these fibers begin and extend?
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Purkinje fibers, begin within the apex of the heart and extend through the walls of the ventricles.
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What are some characteristics of purkinje fibers?
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Larger than other muscle fibers, conduction is extremely rapid,
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Where does the impulse of the purkinje fibers spread?
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immediately throughout the ventricular myocardium, stimulating it to contract.
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what can monitor the electrical activity of the conduction system, or more correctly, its effects on the myocardium?
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Electrocardiography which generates an electrocardiogram
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What is an electorcardiograph?
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Monitors the electrical activity of the conduction system and its effects on the myocardium...generates an EKG or ECG
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