Capillary Filtration Flashcards
features of capillaries
0.5-1mm long
5-8µ in diameter
0.2µ thick
allow for mass exchange of materials
pressure and flow of capillaries
32cm H20 at arterial end
22cm H20 at venous end
average flow velocity 700mm/sec
average transit time 0.25 - 2 seconds
what makes up capillary structure
endothelial tube
vacuoles
intercellular junctions
pericytes
2 types of capillary junctions
Gap/tight junctions
mechanisms of transport in endothelial cell
O2/CO2/solutes - diffusion
water - filtration
macromolecules - transcytosis(similar to active transport)
endothelial glycocalyx
fibrillar glycoproteins
cover intellectual gaps
important to capillary filtration
determinants of capillary filtration(starling forces)
balance of osmotic and hydrostatic pressure
how does venous pressure lead to swelling
increase venous pressure
increased hydrostatic capillary pressure
increases fluid filtration rate
tissue swells
revised model of forces on cell
hydrostatic capillary pressure opposed by interstitial pressure which is opposed by osmotic pressure exerted by endothelial glycocalyx
Starling equation
Jv = Lp .A .[(Pc- Pi) – σ(Π𝑖−Π𝑔)]
Jv: Fluid Filtration Rate
Lp: Hydraulic Conductivity
A: Capillary surface area
Pc: Hydrostatic Capillary Pressure
Pi: Hydrostatic pressure in the interstitium
Π𝑝: Plasma colloid osmotic pressure
Π𝑔: Glycocalyx osmotic pressure
σ: Reflection coefficient
reflection coefficient
how likely it is larger molecules cant make it through gap in glycocalyx
hydraulic conductivity
is affected by number of open endothelial junctions, size of intellectual cleft gaps, permeability of glycocalyx
oedma
swelling of tissue
fluid accumulates in tissue
caused by increased venous pressure NOT arteriolar
