unit 3 definitions Flashcards
pulse pressure
difference between systolic and diastolic pressure (=SBP-DBP)
mean arterial pressure
average pressure driving blood forward into tissues throughout cardiac cycle (DBP +1/3(SBP-DBP))
systolic pressure
during contraction of heart, maximal arterial pressure
diastolic pressure
during relaxation of heart, minimal pressure in arteries when blood is draining off into vessels downstream
cardiac output
total volume of blood ejected by each ventricle each minute
CO=HR x SV
end systolic volume
blood left after the ventricles contract
stroke volume
volume of blood pumped by each ventricle with each heart beat
SV=EDV-ESV
end diastolic volume
blood in ventricle after it is completely filled
preload
stretch that volume of blood places on the walls of the ventricles at EDV (diastole)
afterload
resistance blood experiences as it leaves ventricle (systole)
what increases contractility
sympathetic nervous system
ejection fraction
fraction of blood pumped out with each heart beat
SV/EDV x 100
below normal means decrease in contractility
how to increase contractility
epinephrine (push epi!)
what does aldosterone do
stimulate kidney to pull sodium into it
RAAS
activated when blood pressure and volume is too low (explain how it works)
ANP (atrial natriuretic peptide)
produced by atria when blood pressure or volume is too high (explain)
vasoconstriction
constriction of blood vessel
more resistance
more difficult to flow
CO does down
if you activate SNS…
more contractility
increase in SV
increase in CO
increase in BP
vasodialation
dilation of blood vessel
less resistance
easier to flow
CO goes up
high afterload
decrease in SV, harder to flow, decrease in CO
where does the greatest change in pressure happen in respect to systemic circulation
small arteries and arterioles
total peripheral resistance
sum of all vascular resistance in systemic circulation
if TPR goes up…..
if TPR goes down….
BP goes up
BP goes down
