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27 Cards in this Set
- Front
- Back
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What does the heart's conduction system do?
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Controls the generation and propagation of electrical signals or action potentials that cause the heart's muscles to contract and pump blood.
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How is the heart's electrical activity measured?
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Electrodes are placed on the skin from which a composite recording is produced in the form of a graph known as a Electrocardiogram abbreviated as ECG or EKG.
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In a normal heart, where does each beat originate?
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In the right atrium with an action potential from the sinoatrial node.
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The sinoartrial node is referred to as the heart's...
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The heat's natural pacemaker.
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What phase does the electrical activity of sinoatrial node induce?
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Atrial Systole
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Describe the Atrial Systole phase.
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This is where the electrical signal spreads across both atrium causing the muscles cells to depolarize and contract.
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On the ECG the atrial depolarization is represented as what?
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The P wave.
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The period of conduction that follows atrial systole and precedes the contraction of the ventricles is depicted on the ECG as?
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The PR segment.
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The PR segment on the ECG is depicted as?
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A flat line following the P wave.
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When the electrical signal leaves the atria it enters the ventricles via?
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Atrioventricular node also known as the AV node.
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Where is the atrioventricular node?
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In the interatrial septum.
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Where does the electrical signal go from the atrioventricular node?
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To the Bundle of His.
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Where does the electrical signal go after entering the Bundle of His?
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Through the bundle branches
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How is the electrical activity represented on the EKG as it travels through the Bundle of His?
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As the downward Q wave.
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How is the electrical activity represented on the EKG as it spreads through the bundle branches?
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At the upward R wave.
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How is the electrical activity represented on the EKG as it spreads through the Purkinje Fibers?
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As the downward S wave.
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Where are the Purkinje Fibers located?
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Along the ventricle walls.
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As the electrical signal spreads through the ventricle walls what do the contractile fibers do?
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Depolarized and contract rapidly.
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The depolarization and contraction of the ventricle walls induce what?
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Ventricular systole.
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How is the ventricular depolarization represented on the EKG?
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By the QRS complex.
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What else occurs during the QRS complex?
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Atrial repolarization which is hidden on the EKG by the QRS complex.
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What happens as the electrical signal passes passes out of the ventricular walls?
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The ventricular walls relax and and recover which is a state that is described as the ventricular diastole.
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How is ventricular diastole represented on the EKG
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As a dome shape T wave.
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The T wave marks what?
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Ventricular repolarization.
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What is the ST segment on the EKG?
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It is a depiction of the ventricular walls repolarization.
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What does the QT Interval represent?
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The time it takes the repolarization and depolarization to occur.
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Is an EKG a tracing of a single action potential?
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No. It is a amalgamation of the many action potentials that constitute the electrical activity of the heart.
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