Cardiac Output Flashcards
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
what do chronotropic agents do
increase speed conduciton
effect of B1 on the heart
- increase force of contraction
- increase conduction velocity
- increase speed of contraction/relaxation
- increase rate of rise of pacemaker potential
increasing the HR has what effect on stroke volume
decreases
what is the most important limiting factor for CO
mean systemic filling pressure (Psf)
