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24 Cards in this Set

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