Cardiology 7.7 Flashcards
for EC coupling what has to happen
Ca increases
AP
rise in cytoplasmic calcium is called
cytoplasmic transient (95)
relationship b/w intracellular calcium & muscle tension
very steep relationship
when cell is relaxed intracellular calcium is low
if calcium doesn’t come into cell through calcium current the SR
will not release calcium & won’t get calcium transient
the major way you vary strength of contraction of cardiac muscle
he didn’t say
describe structure of ventricular myocyte and difference b/w skeletal
SR contacts T tubule is similar to triad in skeletal muscle but is not voluminous SR - only at contact site is where it is released
draw out structure of myocyte
pg 96
in heart have calcium channels in t tubule across from
ryanodine receptors (calcium release channels)
what is a couplon
unit of Ca channels and RyRs
ryanodine receptor in cardaic vs. skeletal
ryanodine receptor is separate from calcium channel in cardiac muscle
with each beat the heart needs what that skeletal muscle doesn’t need
calcium influx with each beat
in heart if calcium isn’t released it won’t contract
how is calcium put back into SR
SERCA
beat to beat entry of calcium, with each beat in cardiac cell, how do you get calcium out
sodium calcium exchange (doesn’t need ATP)
SERCA
Calcium pump
what is most important way to get calcium out in cardiac
sodium calcium pump
does sodium calcium pump need ATP
no
how much sodium vs. calcium in pump in cardiac
3 sodium in for 1 calcium out
in cardiac muscle when you apply EPI & NE what happens regarding calcium
bigger calcium current and bigger release from SR and more forecful contraction
why does HR go up when excersie
EPI & NE released, stimulating more calcium & rate of diastolic depol increases so faster HR. force of contractino also increases b/c of bigger calcium currnet
calcium by itself is insufficient to cause
contraction
what do you need calcium to do to to cause contraction
binds to ryanadine receptor, opens, big release of calcium (calcium transient).
if you delay the rate of calcium reuptake what happens to tension
slow the rate of relaxation
if you block calcium current will not get calcium release from
SR
what happens to tension if you have EPI & NE
get faster and stronger rate of tension (pg 100)
pressure development in left ventricle with EPI & NE
steeper rise in ventricular pressure and faster rate of decline
ECG is used to detect
problems with heart - ischemia, infarction, rate & rhythm, etc. basically electrical activity in a pt.
when pt is in ER what is first thing you do
see if their heart is working- measure ECG
slow conduction in ventricles what would get longer on ECG
QRS
the wider the QRS is reflection that
it took longer to propegate to ventricles
what are you measuring with ECG
surface potential (not transmembrane, but transmembrane is causing the surface potential to change)
right leg electrode is
ground electrode
if you just have upward signal in QRS it is
R wave
if up and down in QRS it is
R and S wave
R wave followed by S wave and then another up it is a
R prime wave
if first signal goes down in QRS it is
QS wave
if it goes down and up only it is is
QR wave
draw out the different kind of waves
pg 112
if you subtract A-B you get
inverted t wave (you don’t normally see that) you see it in atria - first one that depol are first to repol and you get inverted t wave but don’t see it b/c it’s during QRS
why do you get positive t wave
in heart epicardial cells have shorter AP duration. they’re activated later but they have shorter AP duration (pg 113 right picture) so A-B is still positive.
t wave inversion is one thing that happens during
ischemia
t wave inversion during ischemia
shortened AP duration on epicardial surface of heart
dipol is measure if
difference in one part of heart compared to another
max dipole is biggest
charge separation
little separation is
small dipole
dipole has positive and negative end and it always points towards
resting tissue
if you’re positive electrode and dipole approaching it will give
upward signal
if dipole is running parallel to orientation of electrodes get
maximum signal
positive end of dipole approaching positive end of signal get
positive wave
if dipole going toward negative electrode get
negative (downard) wave
signal ix maximum when dipole oriented parallel to
electrodes
if dipole is perpendicular to electrodes it generates what signal
isoelectric - it’s almost 0
look at pg 116
pg 116
if first cells to depol are first to repol
get inverted t wave
if second sells to depol are first to repol get
positive t wave
what are the bipolar limb leads
I
II
III
what are the unipolar limb leads
aVR
aVL
aVF
what are the chest leads
V1-6
bipolar leads I, II, III generally where do they go
right arm left arm left leg
draw out where leads I, II, III go
pg 122
