Vascular Physiology 2 Flashcards
shock: def?
inadequate BP to maintain critical organ function; usually when systolic <90 mmHg
mean BP how to calculate?
1/3 systolic + 2/3 diastolic BP
pulse pressure?
systolic minus diastolic pressure
vascular compliance: means? in arteries is proportional to?
stretchability of vessel: change in volume in response to change in pressure. to elasticity.
vascular compliance and aging? pulse pressure?
lose elasticity, more rigid collagen = less compliant, more stiff = higher systolic and lower diastolic = increased pulse pressure
tissue blood flow controlled by?
resistance leading to tissues –> small arteries can adjust flow by relaxing/constricting muscular layer. precapillary sphincters can regulate fine-tuned resistance and flow
most of resistance is in?
the arterioles
which organs have high or low resting tone? what are they sensitive to?
high = brain, heart, muscles –> not sensitive to sympathetic, sensitive to metabolic factors aka can only dilate. low = kidneys, skin, gut - sensitive to sympathetics, not to metabolic actors aka can only constrict.
3 main factors changing vessel resistance?
nerve endings, local chemicals, hormones
nerve control of vessel tone?
sympathetic ner
capillaries have ____ that allow? but not?
small gaps: fluid can diffuse in and out. not large enough to let protein leak out into tissue space
pressure at start and end of capillary? which means?
start ~40 mmHg, 20mmHg at end = 20 mmHg driving fluid into tissue space
when fluid leaves capillary, what does it leave behind? result?
leaves behind bulky proteins = oncotic force rises = sucks fluid back in
normal plasma oncotic pressure? interstitial?
plasma ~25 mmHg. interstitial 0 mmHg
net pressure driving fluid out = ?
blood pressure (out) m minus oncotic pressure (in) –> 15 mmHg at start, -5 mmHg at end
