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24 Cards in this Set
- Front
- Back
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How are muscle cells joined together?
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intercalated disks
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How are muscle cells held together?
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desmosomes
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How can each cardiac muscle cell spread an electrical impulse?
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gap junctions
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What are the sympathetic control receptors?
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alpha
beta- 1 beta- 2 |
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What are the parasympathetic control receptors?
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muscarinic
nicotinic |
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What is automaticity
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the ability to initiate an impulse
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What is Excitability?
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the ability to respond to an impulse
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What is Conductivity
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the ability to transmit an impulse
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What is Contractility
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the ability to shorten the cell length
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What is Action Potential?
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the difference in charge on either side of cell wall changes as ions move in and out of the cell
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What is polarized?
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when a cell has a charge farthest away from neutral
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What is depolarized?
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when a cell has a charge closest to neutral
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What is repolarizing?
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when the cell is regaining a charge away from neutral
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What is the starting state of contractile cells?
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~ -90mV
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What is the starting state of conductive cells?
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~ -60mV
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what cardiac cell types contract and make up most of the tissue?
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contractile
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What cardiac cell types rapidly conduct electrical impulses, have automaticity, but no contractility?
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conductive
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what do I(f) channels allow?
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some K+ to exit the cell
and more Na+ to enter the cell |
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What happens when more Na+ enters the cell than K+ leaves the cell?
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The cell charge becomes more positive and the cell begins to depolarize
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What is the threshold for conductive cells?
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~ -40mV
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What happens as cardiac conductive cells approach threshold?
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I(f) channels close
Ca++ channels open, resulting in a continuation of depolarization |
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What happens when cardiac conductive cells reach threshold?
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Lots of Ca++ channels open, Ca++ enters cell, developing a quick positive charge which overshoots neutral
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What happens when cardiac conductive cells reach maximum depolarization?
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Ca++ channels close, slow K+ channels open, allowing K+ to exit cell
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What happens when cardiac conductive cells reach repolarization?
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Slow K+ channels open, K+ exits cell, charge becomes less positive until it reaches -60mV where it is ready to depolarize again
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