Physiology Flashcards
What is the stroke volume?
the volume ejected when the ventricular muscle contracts
What is the stroke volume equal to?
end diastolic volume - end systolic volume
What does the Frank-Starling law describe?
relationship between venous return, EDV and stroke volume
the more the ventricle is filled with blood during diastole (END DIASTOLIC VOLUME), the greater the volume of ejected blood will be during the resulting systolic contraction (STROKE VOLUME)
What is afterload?
the resistance into which heart is pumping
What happens if afterload increases?
heart unable to eject full SV, so EDV increases
What happens if afterload chronically increased?
ventricular hypertrophy
What is a positive inotropic effect?
increased force of contraction
If heart rate = 75bpm, how long does
a) diastole?
b) systole last?
a) 0.5 s
b) 0.3 s
When is aortic pressure greatest?
ejection phase of ventricular systole
When do AV valves close?
during ventricular contraction when the ventricular pressure rises higher than the atrial pressure
When do the aortic and pulmonary valves open?
When the ventricular pressure exceeds aorta/pulmonary artery pressure
What sound occurs when aortic and pulmonary valves open?
silent
When do the aortic and pulmonary valves close?
When the ventricular pressure falls below aortic/pulmonary pressure
What sound occurs when
a) AV valves close?
b) aortic and pulmonary valves close?
a) 1st heart sound (LUB)
b) 2nd heart sound (DUB)
What is the dicrotic notch?
falling aortic pressure slightly rises due to vibration from valve closing
