Cardiac Output Flashcards
(28 cards)
volume of blood ejected from one ventricle of the heart during one minute
cardiac output
what is the equation for cardiac output
CO = HR + SV
what is the equation for ejection fraction
EF = (EDV-ESV)/EDV
fraction of blood pumped each beat
what is normal value of ejection fraction
55-67%
what are the ways to regulate cardiac output
- preload
- afterload
- inotropic state of cardiac muscle (amount of Ca2+)
how does the heart modulate inotropic state
amount of calcium in SR
90 percent of calcium comes for the
SR
what are the physiological modulators of inotropic state
- sympathetic via activation of cAMP-> phosphory of Ca channels-> faster AP conduction
- parasympathetic via G activation-> low cAMP-> low phosphory of Ca
what does phosphorylation of phospholambam do
reduces phospholambams ability to inhibitn SERCA 2 from storing Calcium ion SR
what effect does a higher inotropic state have on ESV
decreases or lowers
what effect does a higher inotropic state have on stroke volume
increases
what are cardiac glycosides and how do they work
inhibit Na/K pump -> accumulation of Na in cell -> Na/Ca exchanger -> higher calcium inlfux, stronger contraction
what doe methylxanthines do
(caffeine) inhibit PDE -> cAMP
how can DHP channels become inhibited
ischemia (low ATP)
H+
long resting length _____ velocity
increases
stroke volume increases as _____ ______ increases
ventricular volume
what does hypertension do to the afterload
increases the afterload
T/F the length-tension relationship can compensate (in some situations) for an increase in preload
True
LVEDV stands for
left ventricular end diastolic volume = full of blood with low pressure
increased afterload, leads to a reduced SV, leads to a(n) _______ EDV
increased
increase preload = _____ SV
increase
positive inotrope = ______ SV
increase
increase afterload = ______SV
decreased
how do chronotropic effects increase the filling time
by reducing systolic time
