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20 Cards in this Set
- Front
- Back
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AVF Leads for ECG
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Uses L foot as the + lead and arms as the - leads.
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AVR leads for ECG
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Uses R arm as the + lead
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AVL lead for ECG
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Uses L arm as the + lead
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Autonomic Nervous System
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Controls all organs and organ systems. Consists of sympathetic and opposing parasympathetic systems.
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Sympathetic NS terminal ends secrete what?
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Nor-epinephrine an adrenaline- like neurotransmitter that activates adrenergic receptors.
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Parasympathetic NS terminal ends secrete what?
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Acetylcholine which exclusively activates cholinergic receptors.
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What does Nor-epinephrine do?
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Stimulates the Beta 1 (adrenergic) receptors stimulating the SA node to pace faster.
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Where else does N-epi work?
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AV node in conjuction w/ SA node to improve conduction and increase the myocardial contraction
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Acetylcholine does what?
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Activates the cholinergic receptors that inhibit the SA node decreasing the HR and depresses the AV node.
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What is the SA node?
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Heart's pacemaker: 60-100 bpm dominant center of automaticity
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If SA node fails what then?
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Other pacemakers w/ automaticity or ectopic foci will take over. These are in the atria, the ventricles, and the AV junction.
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Atrial automaticity rate?
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Inherent rate: 60-80 bpm
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AV junction rate?
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A slower rate: 40-60 bpm
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Ventricular rate?
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20-40 bpm
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What is Rapid Automaticity?
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Suppresses the slower rates to use the highest heart rate available.
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P wave?
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Depolarization of the atrial myocardium. Stimulus passes down the atria to the AV node where it pauses.
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Why is there a pause after the atrial depolarization?
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Allows the contraction of the atria to force the remaining blood into the ventricles.
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What is the QRS complex?
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Depolarization of the ventricles
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What is the T wave?
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The repolarization of the ventricles.
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When does the atrial repolarization take place?
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It happens during the depolarization of the ventricles and cannot be seen electrically.
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