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24 Cards in this Set
- Front
- Back
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Av bundle
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called the bundle of his, is normally the only electrical connection between the atria and the ventricles, once an impulse enters the AV bundle, it reavels to the interventricular septum and enters the right and left bundle branches
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left bundle branch
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supplies the massive left ventricle
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Purkinje fibers
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conduct action potentials very rapidly, as fast as small myelinated axons
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ventricular contraction
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proceeds in a wave that begins at the apex and spreads toward the base
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segments
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times between waves, they extend from the end of one wave to the start of another
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intervals
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are more varible, but always include at least one entire wave
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absolute refractery period
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corresponds with the onset of the QRS complex to approciimately the peak of the T wave, cardiac cells cannot be stimulated to conduct an electrical impulse, no matter how strong the stimulus
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action potential
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a reflection of the difference in the concentration of ions across a cell memebrane at any given time
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amplitude
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the height voltage of wave form on the ECG
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arrhythmia
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absence of rhythm
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automaticity
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the ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse without being stimulated from another source
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conductivity
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the ability of a cardiac cell to receive an electrical stimulus and conduct that impulse to an adjacent cardiac cell, change activity by changing drugs
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contractility
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the ability of cardiac cells to shorten, causing cardiac muscle contraction in response to an electrical stimulus
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excitability
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the ability of cardiac muscle cells to respond to an outside stimulus
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polarized state
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period of time following repolarizing of myocardial cell (resting state) when the outside of the cell is positive and the interior of the cell is negative
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Purkinje fibers
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an elaborate web of fibers distributed throughout the ventricular myocardium
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relative refractory period
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corresponds with downslope of the T wave cardiac cells can be stimulated to depolarize if the stimulus is strong enough
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Supraventricular
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originating from a site above the ventricles
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end siatolic volume (EDV)
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the max amount of blood each ventricle contains prio to ventricular systole contraction (about 130 ml)
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Stroke volume (SV)
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the amount of blood each ventricle ejects during systole. at rest it is about 60% of the EDV (ejection fraction)
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end systolic volume (ESV)
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the amount of blood remaining in the ventricle when the semilunar valve closes at the end of the ventricular contracting abut 50 ml r 40% f the EDV
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cardiac output (CO)
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the amount of blood pumped by each ventricle in one minute
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myocardial infarction (MI)
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heart attack, part of the coronary circulation becomes blocked, and cardiac muscle cells die from lack of oxygen
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enzymes that indicate cardiac distress
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cardiac troponinT, cardiac troponin I, MB isomer
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