venous systemvenous system tom horváth m.d. ph.d. topics 1.structural aspects 2.hemodynamic...
TRANSCRIPT
Venoussystem
TomHorváthM.D.Ph.D.
Topics
1. Structuralaspects2. Hemodynamicfunctions3. Pressure-diameterbehavior4. Centralvenouspressure&vascularfunction
Thecirculatorysystem
pulmonaryveins
systemicveins
Pressuredistribution
Distribution of total blood volume
veins64
arteries13
pulmonarycirculation
9
capillaries7
heart7
Totalbloodvolume~5.5Liter
Venousbloodvolume~3.52Liter
Hemodynamicfunctionsoftheveins
• Conduitfunction– channelbloodtowardtheheart
• Flowrectification(anti-gravitationalfunctions)– venousvalves– musclepump– abdominalpump
• Capacityfunction– bloodstorage(60-70%)
• spleen~150ml• liver~200-300ml• abdominallargeveins~300ml
Structuralaspects– arteriesvs.veins
Structuralaspects– arteriesvs.veinsII.
Arteriesandveinsunderpressure
COMPLIANCE:DV/DP
DISTENSIBILITY:DV/(DP× V0)
Flowrectification– valves– I.
Flowrectification– musclepump– II.
Flowrectification– thoraco-abdominalpump– III.
INSPIRATIONbloodflowsrapidlytowardthechest
EXPIRATIONbloodflowsslowstowardthechest
Centralvenouspressure
• Visafronte(fromthefront~RA)
• Visatergo(fromtheback~LV)
ThevascularfunctioncurveI.
Conceptof“deadpressure”a.k.a.meancirculatorypressure
• Q=5l/min• Pa =102mmHg• Pv =2mmHg• Ph =Pa - Pv =100mmHg• TPR=Ph/Q=20mmHgmin/l• C=DV/DP• Ca/Cv =1/19
ThevascularfunctioncurveII.
ThevascularfunctioncurveIII.