Cardiovascular system Flashcards
CO=
HRxSV
MAP=
DP + 1/3 PP
PP=
SP - DP
Requirements for effective cardiac function
No arrhythmia No stenosis of valves No insufficiency of valves Muscle contractions must be forceful Ventricles must fill adequately during diastole
Cardiac output
quantity of blood per unit time pumped into the aorta by the heart
also equals the quantity of blood per unit time the flows through the circulation
Stroke volume
amount of blood ejected out of each ventricle
Major determinants of stroke volume
Ventricular preload- length of muscle at onset of contraction
Ventricular afterload- tension of muscle during contraction
myocardial contractility
Variation in SV
due to cardiac filling during diastole
SV increases as EDV increases
Starlings law
Larger the ventricular EDV— the larger the stroke volume
MAP
average pressure over the entire cardiac cycle
Dichrotic notch
small dip caused by the backfilling of the aortic valve as it closes
Largest drop in MAP occurs where
across the arteriolar segment
-sight of highest vascular resistance
Short-term control of MAP
altering CO and TPR
Long-term control of MAP
altering blood volume via kidneys