Contractility and Cardiac Output Flashcards
What is ionotropy generally proportional to?
amt of calcium that is available to troponin on actin filaments
What is preload defined as?
left ventricular end-diastolic volume
end diastolic fiber length
What is afterload defined as?
Pressure required to open the aortic valve
What is stroke volume?
vol of blood ejected by ventricle w/ each beat
SV = EDV - ESV
What is ejection fraction?
fraction of the EDV ejected in each stroke volume
measure of efficiency and contractility
EF% = SV/EDV (usually abt 55%)
What is cardiac output?
total volume of blood ejected by ventricle per min
CO = SV*HR
What is normal ejection fraction?
55%
What is normal CO?
5 L/min
What is the frank-starling relationship for cardiac output?
the volume of blood ejected by the ventricle depends on the volume present at the end of diastole
relates length-tension to functionality
How does the EDV relate to venous return?
CO = venous return
What is the relationship btw CO and venous return?
mean systemic pressure is proportional to blood volume and preload
at equilibrium, CO = venous return
What does the cardiac function curve tell you?
represents Fank-starling relationship –> as systemic pressure increases, cardiac fxn increases
What happens to afterload if cardiac function is enhanced?
afterload decreases
What occurs in cardiac failure?
decreased inotropy
decreased vascular compliance
increased blood volume
increased SVR
