N471 Exam 3 Review QUESTIONS WITH ANSWERS,

N471 Exam 3 Review QUESTIONS WITH |\ |\ |\ |\ |\ |\




ANSWERS

What do ECG's do? - CORRECT ANSWERS ✔✔detect abnormal
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transmission of cardiac impulses through the conductive tissue; |\ |\ |\ |\ |\ |\ |\ |\


diagnose specific abnormalities by evaluating electrical activity of
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the myocardium
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What will an ECG tell you? - CORRECT ANSWERS ✔✔1. Size of
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heart
2. Orientation of heart
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3. Rhythm disturbances
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4. Injury, ischemia, or infarct
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5. Electrolyte abnormalities
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6. Drug toxicity
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What are the parts of the myocardium conduction system and
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the rates of nodes? - CORRECT ANSWERS ✔✔- SA node: rate=60-
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100 bpm |\




- Internodal fibers
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- AV node "Junction": rate=40-60 bpm
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- Bundle of His
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- Bundle branches
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-Perkinje fibers |\

,What does the bundle of His do? - CORRECT ANSWERS
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✔✔conducts impulses to bundle branch system |\ |\ |\ |\ |\




what do the bundle branches do? - CORRECT ANSWERS
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✔✔conducts impulses through ventricles |\ |\ |\




what do the perkinje fibers do? - CORRECT ANSWERS
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✔✔conducts impulses into subendocardial layers; depolarize from
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endocardium to epicardium
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What does the T wave represent? - CORRECT ANSWERS
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✔✔repolarization of ventricles |\ |\




What does the p wave represent? - CORRECT ANSWERS ✔✔atrial
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contraction (depolarization) |\




If the T wave is the repolarizing of the ventricle, where is the
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repolarizing of the atria? - CORRECT ANSWERS ✔✔Lost in the
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QRS complex
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What do all heart cells have? - CORRECT ANSWERS ✔✔a
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membrane potential which is simply a difference in electrical
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charge across a semi-permeable membrane
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What are the two phases of potentials? - CORRECT ANSWERS
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✔✔Resting membrane potential (RMP) or action potential
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,What are the two stages of action potentials? - CORRECT
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ANSWERS ✔✔depolarization and repolarization
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What is automaticity? - CORRECT ANSWERS ✔✔the ability to
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spontaneously depolarize |\




what is rhythmiticity? - CORRECT ANSWERS ✔✔the ability to
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depolarize regularly |\




What is refractoriness? - CORRECT ANSWERS ✔✔the state of a
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cell during repolarization when cells cannot depolarize regardless
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of the intensity of the stimulus or require a much greater
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stimulus than normal |\ |\




What is the Na+ concentration like? - CORRECT ANSWERS
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✔✔greater outside the cell than inside |\ |\ |\ |\ |\




what is the K+ concentration like? - CORRECT ANSWERS
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✔✔greater inside the cell than outside |\ |\ |\ |\ |\




What causes changes in resting membrane potential? - CORRECT
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ANSWERS ✔✔chemical, electrical, or mechanical stimulation
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What are the two types of cells in action potential? - CORRECT
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ANSWERS ✔✔Myocardial cell and pacemaker cell
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, What is the process of action potential in a myocardial cell? -
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CORRECT ANSWERS ✔✔1. Stimulus hits the resting membrane
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2. Influx of Na+ produces rapid depolarization
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3. Initial repolarization as some K+ leaves the cell
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4. Slow influx of Ca+ keeps inside positive (Ca entering the cell
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provides for release of intra-cardiac Ca stores and muscle
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contraction)
5. Repolarization phase; inactivation of slow Ca channel begins
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preventing further influx of Ca; K+ continues to leave the cell;
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leads to cell becoming more negative, leading to reestablishment
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of the RMP
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6. Excess Na+ that entered the cell during depolarization is
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removed via the Na-K Pump; inside the cell returns to a negative
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state and outside a positive in preparation for the next stimulus
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which will lead to depolarization
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What is the process of action potential in pacemaker cells? -
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CORRECT ANSWERS ✔✔1. a slow influx of Na+ results in a
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gradual incline |\




2. depolarization and repolarization occur due to a steady influx
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of Na and efflex of K in these specialized cell membranes
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*they require NO outside stimulus to depolarize spontaneously.
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What do pacemaker cells provide? - CORRECT ANSWERS ✔✔the
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electrical stimulus for depolarization of the myocardial cells
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