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30 Cards in this Set
- Front
- Back
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what is Depolarization
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Electrical stumulus to cells causes an influx of sodum and calcium into the cells. The two contradctile proteins, actin and myosin use their chemical energy to slide past one another.
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what is Repolarization
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When calcium and sodium are pumped back into storage after depolarization and the cell is ready to start process over.
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what is Automaticity
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initiateing impluses in heart
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what is excitability
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hearst ablility to respond to impulses
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what is conductivity
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hearts ability to transmit impulses
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what is conractility
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hear muscle response
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electrical stages of the hear
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1. Stumulus
2. depolerization 3. repolarization 4. refractory period |
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what is rhe refractory period
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period of time during the repolariztion where the cell is resistant to futher stimulation.
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what dose the refractory period prevent
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premature activation and sustained activation
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conduction system of the heart 6 parts
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SA node
intaatrial pathways AV node Bundle of HIS bundle brances purkinje fibers |
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P- Wave
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attrial contracts-depolarization
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PR- interval
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aria to av nodel- little bit of time.
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QRS
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ventricals contracting- depolarization
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what are arrhythmias
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Abnormal heart beats result form irregularities in automaticity, excitablility, conductivity, contractility.
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Types of arrhythmias are defined by
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Site of orighin and mechanism of conduction
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mechanisms of conduction
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Tachycarida, Bradycardia, flutter, fivrillation, premature, heart block
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Site of origin of arrhytmias
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Sinus, atria, AV(nodal junction), ventricles
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Things that enhance automaticity
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Lack of oxygen
Chemical toxicity stretch on fibers |
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Heart block stages
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1degree messages slower
2 degree sometimes messages get through sometimes not 3degree not getting any messages |
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what do antiarrhythmics do
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they depress automaticity, lowing conduction rates, increasing refractoriness to premature stimulation. accomplished by altering movement of one or more ions across the hear membranes.
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Indications for Antiarrhytmics
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Antiarrhythmics are selected according to type of abnormal rhythm determined by EKG
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Contraindications of antiarrhythmics
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there are no containdications to anti arrhytmics when needed to stop a fatal arrhythmia.
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Actions/ classes of Antiarrhythics: class I
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membranepstabalizing agents, work on the fast sodium channels.
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Actions/ classes of antiarrhythmics: class I A
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by blocking rapid sodium paths, delays repolarization.
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Actions/ classes of antiarrhythmics: I B
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Block sodium, but accelerate repolarization
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Action/ class of antiarrythmics: I C
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Massive blocking of sodium without much effecto on repolarization
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Action/ class of antiarrythmics: II
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beta blockers, block B receptors in the SNS
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Action/ class of antiarrhythmics: III
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prolong repolarization
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Action/class of antiarrhytmics: IV
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inhibit the slow calcium channels
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Quinidine ( Quinidex)
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Subclass: IA
Acion blocks sodium pathways to cause delayed repolarization. Indications: atrial arrhythmias for long term use Side effects Av block, hypotension, decrased cardiac output, widened QRS, low platelets, GI upset, cinchonism |
