outline
- design of microcirculation
- structure and types of capillaries
- diffusion- process and factors affecting
- regulation of plasma and interstital fluid volumes (filtration) - process and factors affecting
Design of microcirculation
What is microcirculation
microcirculation are the capillaries which act as the diffusion surface capillaries has 8 micron diameter microcirculation of each organ is built for that organ
metarterioles aka throughfare vessels aka shuft allows blood to quickly run through the area
pericytes are vascular mural cells which act to help constrict capillaries
blood only remains in the capillaries for 0.5-2 secs this is enough for change also
heart and brain need lots of blood and therefore is more densely packed with capillaries
Structure and types of capillaries
capillaries hace endothelium and a basement membrane
law of laplace T = Pxr transmural pressure times radius of vessel = tendency to tear small radius mean low tendency to burst
glycocalyx prevent proteins from passing through capillaries
continuous brain heart skin muscle
fenestrated high water turnover tissues exocrine endocrine kidney joints eye choroid plexus gut mucosa
sinusoid (discontinuous) liver spleen bonemarrow
large gaps for max encahnge
Diffusion – process and factors affecting
solute exchange
diffusion
flus = (surface area/Thickness)xDiffusion constantx(partial pressure1-partial pressure2)
Effecting factors
a. Molecules Type of molecule for example proteins cannot pass through glycocalyx
size of molecule albumin cannot usually pass through capillary
metabolic demand diffusion gradients formed etc
b. Recruitment of capillaries opne extra capillaries
fluid exchange
follows starlings law of equilibrium and or bulkflow
capillary exchange depends on the hydrostatic pressure and oncotic pressure
if there is excesses in fluid exchanges different problems can occur as a result
Regulation of plasma and interstitial fluid volumes (filtration) – process and factors affecting
balancing of oncotic pressure and hydrostatic pressure