CAPILLARIES 2 Flashcards
abnormalities in fluid exchange leads to what?
oedema / swelling
what does fluid movement across capillary walls depend on
balance between hydraulic and oncontic pressures across the capillary wall
when large molecules can not pass through the membrane what happens
-they exert an osmotic pressure termed oncotic pressure which creates a suction force to move fluid into capillary
when fluid moves across membrane into interstitial space due to blood flow what does it exert
hydraulic pressure
what four pressures determine filtration rate
osmotic pressure
-plasma proteins ( pi p)
-interstitial proteins ( pi i)
hydrostatic pressure
-capillary blood pressure (Pc)
-interstitial fluid pressure (Pi)
overview of the role of lymphatic circulation
returns excess tissue fluid/solutes back to the cardio-vascular system
about 8 litres per day are filtered
overall control of extracellular fluid balance depends on?
-capillary filtration
-capillary reabsorption
-lymphatic system
what starling factors determine changes in fluid balance
-circulation
-interstitial fluid
-lymphatic system
what does increased Pc give ( capillary pressure )
oedema
what is oedema
excess fluid within interstital space
causes of oedema
-increased capillary pressure
-decreased plasma protein oncotic pressure
-inflammatory response
-lymphatic problems
what does low protein oedema lead to
-malnutrition/malabsorption
not enough protein intake to make plasma proteins
-reduced plasma proteins concentration
-reduced plasma oncotic pressure
-fluid efflux from capillaries into interstitial fluid
-leads to oedema
what causes inflammation
-increased Lp
-increased protein permeability
-chemicals
-infection
what triggers swelling
local chemical mediators of inflammation , this causes a large increase in capillary permeability
2 lymphatic problems
-filariasis/elephantitis -nematode infestation , larvae migrate to lymphatic system and mate to form nests which block lymph drain
-lymphoedema - caused by surgery to treat testicular cancer
