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41 Cards in this Set
- Front
- Back
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Depolarization and repolarization are _________ events.
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electrical
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Contraction and relaxation are __________ events.
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mechanical
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A negatively charged rested cell is called what?
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polarized
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During cell recovery, sodium and potassium ions are shifted back to their original places by way of the _______.
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sodium-potassium pump
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Depolarization should result in what?
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muscle contraction
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Repolarization should result in what?
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muscle relaxation
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The QRS complex on the EKG represents what?
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depolarization
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What does the P wave represent?
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atrial contraction
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Define: Repolarization
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when the heart recovers electronically
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Define: Depolarization
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contraction of cardiac cells
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What does the QRS wave represent?
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ventricular contraction
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What does the T wave represent?
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ventricular relaxation
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Which wave only occurs occasionally in some patients?
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the U wave
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What is a baseline?
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the flat line that separates the various waves
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What is the Inherent (escape) rate for the sinus node
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60-100 beats per minute
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What is the Inherent (escape) rate for the AV junction
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40-60 beats per minute
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What is the Inherent (escape) rate for the Ventricle
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20-40 beats per minute
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Cardiac cells at rest are electrically ___________
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polarized
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Depolarization and repolarization are what kind of events?
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electrical
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List the 4 characteristics of heart cells.
Which are electrical and which are mechanical? |
automaticity - electrical
conductivity - electrical excitability - electrical contractility - mechanical |
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what is automaticity
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the ability to create an impulse without outside stimulation
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what is conductivity
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the ability to pass impulses to neighboring cells
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what is excitability
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the ability to respond to stimulus by depolarizing
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what is contractility
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the ability to contract and do work
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Specialized electrical cells called pacemaker cells in the heart are arranged in a system of pathways called the ____________.
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Conduction system
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What is the primary function of the conduction system?
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to transmit minute electrical impulses from the SA node to the atria and ventricles, causing them to contract
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In normal conduction, which pacemaker is dominant?
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SA node
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What is escape?
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when the dominant pacemaker slows down or fails and the lower site becomes the pacemaker
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What are the four structures that make up the hearts conduction system?
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SA node (sinoatrial)
AV node (atrioventricular), bundle of his right and left bundle branches |
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What are the two types of cardiac cells?
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Myocardial cells
Specialized cells |
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What are myocardial cells responsible for?
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contraction and relaxation
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What are the specialized cells responsible for?
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generation and conduction of electrical impulses
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What are the major electrolytes that affect cardiac function?
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sodium (NA+)
potassium (K+) Calcium (CA+) |
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absolute refractory period
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no stimulus can cause depolarizaion - occurs at onset of the QRS to the peak of the T wave
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relative refractory period
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strong stimulus will result in depolarization - occurs during the down slope of the T wave
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superonormal refractory period
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weak stimulation can cause depolarization
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what is the PR interval?
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distance between the P wave and QRS
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what is the ST segment?
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flat line between the QRS and T wave
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what is the baseline?
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flat line between the T wave of one beat and the P wave of the next beat
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what is usurpation?
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when a lower pacemaker takes control and becomes the new pacemaker at a faster rate
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List the phases of Acton Potential
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phase 4 - cardiac cells at rest
phase 0 - depolariztion - releases energy (QRS) phase 1 & 2 - early repolarization (ST segment) phase 3 - rapid repolarization (P wave) |
