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38 Cards in this Set
- Front
- Back
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What are automaticity foci?
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Focal areas of the heart that have electrical automaticity.
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Where is the SA Node located?
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In the upper-posterior wall of the RA.
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What is the sinus node?
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Another term for the SA Node.
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What is the P wave on an EKG?
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Depolarization and contraction of both atria.
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Purpose of the AV valves?
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Prevent backflow of blood and electrical insulation.
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What happens to electrical conduction in the AV Node?
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Depolarization slows down to allow blood flow into ventricles.
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How does the AV Node conduct depolarization?
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Ca++ ions.
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What is the ventricular conduction system?
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His Bundle and the Left and Right Bundle Branches.
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What type of fibers make up the ventricular conduction system?
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Purkinje fibers.
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What is the QRS complex on the EKG?
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It represents the depolarization of the ventricular myocardium and the initiation of contraction.
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What ions are used in the depolarization of the Purkinje fibers?
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Na+ ions.
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Which wave is often absent on the EKG?
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Q wave.
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What is the ST segment?
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Horizontal segment of baseline following the QRS complex.
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What happens during the ST segment?
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Initial phase of ventricular repolarization.
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What is the T wave and what is happening?
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The hump after the ST segment during which rapid ventricular repolarization occurs.
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What ions are responsible for repolarization?
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K+ ions.
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When does systole occur on the EKG?
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Begins with the QRS and persists until the end of the T wave.
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Does systole span both depolarization AND repolarization of the ventricles?
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Yes.
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What does the vertical amplitude measure on the EKG?
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Voltage.
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What is the length and width of the small boxes on the EKG graph paper?
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1mm.
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How many mm represent 1mV on the graph?
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10mm.
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How are positive (upward) deflections produced?
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Positive charge flowing toward a positive electrode.
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What is the time represented in the distance between two heavy black lines (5mm)?
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0.2 seconds.
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Each tiny square represents how much time?
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0.04 seconds.
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How many leads are there on an EKG?
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12 leads = 6 limb leads + 6 chest leads.
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How many electrodes represent each lead?
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One pair.
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What are the names of the limb leads?
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Lead I, II, III and AVR, AVL, AVF.
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Which are the bipolar leads?
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Leads I, II, III.
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Which are considered unipolar, or positive leads?
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AVR, AVL, AVF.
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Which are the "lateral" leads?
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AVL and Lead I on the left arm.
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Which are the "inferior" leads?
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Leads II, III, and AVF.
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What are the chest leads?
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6 positive electrodes positioned across the chest, centered on the AV Node.
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What is the horizontal plane?
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The plane formed by the positioning of the chest leads.
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On what side of the heart are V1 and V2 positioned?
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The right side.
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On what side of the heart are V5 and V6 positioned?
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The left side.
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Where are V3 and V4 located relative to the heart?
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Over the interventricular septum.
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In what plane are the limb leads positioned?
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Frontal plane.
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What are trunk electrodes?
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Alternative positioning of electrodes in various medical situations.
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