Microcirculation Flashcards
anomalous viscocity
increase in viscosity at low flow rate
formation of Rouleaux affect on flow
at low flow rates, blood appears to have a higher resistance than at faster flow rates
Fahraeus-Lindqvist effect
viscosity of blood depends on the diameter of the tube
axial streaming
tendency of RBCs to accumulate in the rapidly flowing axial lamina
Rouleaux
chain-like aggregates of RBCs which form at low flow rates
plasma skimming
tendency of the cell free plasma to be skimmed off at a branch point of the microcirculation
cellular deformability
ability of the cell membrane to bend affecting flow in the microcirculation
four factors that determine the diffusion rat of a substance between blood and interstitial fluid
concentration difference, surface area for exchange, diffusion distance, permeability of the capillary wall to the diffusing substance
chemical potential
measure of the free energy of a solution, presence of solute on one side of the membrane lowers the chemical potential
osmotic pressure
given as the hydrostatic pressure needed to balance the movement of solute
net shifts in fluid between capillary and interstitial compartments are important for
maintenance of blood volume, interstitial fluid absorption, tissue edema formation, saliva production, sweat production, urine production
transcellular fluid movement
across the cells
paracellular fluid movement
between the cells
net filtration pressure
difference between the hydrostatic and osmotic pressure differences
hydraulic conductivity
constant of proportionality that relates the amount of flow to the net driving force
capillary hydrostatic pressure (Pc)
varies among different tissues, influenced by gravity, higher Pc favors filtration. Is 35 mm Hg at arteriolar end and 15 mm Hg at venous end.
effect of arteriolar and venular constriction and dilation on capillary hydrostatic pressure
constriction increases capillary hydrostatic pressure, dilation decreases capillary hydrostatic pressure.
capillary colloid osmotic pressure
exerts a force that favors fluid absorption, due to proteins plus the excess salt
interstitial fluid hydrostatic pressure
exerts force that drives fluid filtration in loose tissues, exerts force that drives fluid absorption in rigid enclosed compartments (bone marrow or brain)
interstitial fluid osmotic pressure
exerts force that drives filtration
starling equation predicts
filtration at the arteriolar end and absorption at the venular end of most capillary beds
lymphatic system
similar to capillaries but with one way valves, pathway for larger molecules to reenter circulatory system
edema
excess salt and water in interstitial spaces
lymphatic blockage
malignant neoplasms may cause local edema upstream of the sites of blockage
