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What are the 4 properties of the heart?
autorythmicity
contractility
excitability
conductivity
What are the parts of the electrical conducting system?
S
A node
A
V node
P
urkinje's fibers
H
IS bundle
R
ight and left bundle branches
What 2 kinds of cells make up the heart?
Mechanical cells
Cells of electrical system
The cells of electrical system are actually these
Modified cardiac muscle cells
What 2 things do interclated discs contain?
Desmosomes
- attach cells together
Gap junctions
- spread action potentials
What is the resting membrane potential in cardiac cells?
-80 to -90 mv
This ion generates resting membrane potential
K+
What is the Nernst equation?
61.5 log10 (Xo / Xi)
These are 2 types of action potentials in the heart
Fast
Slow
Which cells have
fast response
action potentials?
atrial cells
ventricular cells
His cells
Purkinje cells
Which cells have
slow action
potentials?
AV node
SA node
Fast AP
:
0= Na influx
1= Na close and open
specific
K+ channels
2= open
calcium
channels
3= close
calcium
open K+
4= rest
The refractory period spans this time
depolarization half way down repolarization
Pacemaker Potential:
1.
K+ close
, Na
f
open
2. Na
f
close,
T-calcium
open
3.
T-calcium
close,
L-calcium
open
4.
L-calcium
close,
K+ open
The suppression of all other pacemakers by the SA node is called this
overdrive suppression
Conduction of AP
1
. AP made in SA node
2. Rapid spread through atria
3
.
Delay
4. Goes through His bundle
5.
Goes through ventricles
6. Rest
These cells have the largest diameter with most of gap junctions
Purkinje cells
These cells have small diameter and less gap junctions
AV node cells
Intercalated Disc between cells
Author
Bobopudge
ID
64636
Card Set
CVR2
Description
Autorhytmicity and Conduction in the Heart
Updated
2011-03-31T10:09:22Z
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