Function of arteries and veins Flashcards
distensibility formula
(change in volume)/(change in pressure x original vol.)
veins are… times more distensible than arteries
- same increase in pressure would result in 8 times volume in veins
pulmonary arteries are …. times more distensible than systemic arteries
6
compliance formula
compliance = change in volume/ change in pressure or distensibilty x initial volume
compliance of systemic veins vs systemic artery
24 times (8 times distensible and 3 times the volume)
700 mls gives how much pressure in arteries
100 mmHg if vol. falls to 400 mls pressure falls to 0 2ml/mmHg
venous volume ranges
2000-3500 mls 100 ml/mmHg
venous compartment can maintain normal circulatory function with BV loss of
25%
pressure pulse velocity of transmission
3-5 m/ sec in aorta, 7-10 m/sec in large arteries, 15-35 m sec in small arteries. aortic pressure wave velocity is 15 times faster than actual blood transmission
pulse pressure =
Ps-Pd or SV/Ca
Ps=
SVxHRxSVR+ 2/3 (SV/Ca)
Pd=
SVxHRxSVR+ 1/3 (SV/Ca)
damping effect on pulse pressure
resistance to blood movement and changes in vessel compliance
RAP
0 max =20-30 min=-3 to -5.
RAP contributors
decreased by: increased contractility,decreased venous return (i.e. decreased BV, decreased venous tone, constriction of arterioles).
increased by: decreased contractility, increased venous return (increased BV, increased venous tone, dilation of arterioles)
peripheral venous pressure usually … higher than RAP
4-6. RA must rise this much before before you see rise in peripheral venous pressure
intrabdominal pressure in pregnancy tumors obesity
15-30
pressure in feet standing still
- normally 20. can lose 10 -20% of cbv in 15- 30 minutes if standing still
spleen BV
100 MLS
LIVER BV
SEVERAL HUNDRED MLS
large abdominal veins BV
approx 300 mls.
venous plexus beneath skin BV
several hundred mls
heart BV
50-100 mls
lungs BV
100-200 mls
