Tissue Fluid and Oedema Flashcards
what does blood flow in capillaries depend on?
contractile state of arterioles
how fast is the blood flow through capillaries described?
slow (allows time for exchange of substances)
how are exchangeable protein moved across capillaries?
vesicular transprt
how are hydrophilic substances eg Na+ moved across capillary walls?
through the water-filled pores?
how are lipid soluble substance moved across capillary wall? eg O2
diffusion across endothelial cell
why can plasma proteins not pass the capillary wall?
they are large molecules
what does NFP stand for?
Net filtration pressure
how is NFP calculated?
forces favouring filtration- forces opposing filtration
what are the forces favouring filtration?
capillary hydrostatic pressure
interstitial fluid osmotic pressure
what are the forces opposing filtration?
capillary osmotic pressure
interstitial fluid hydrostatic pressure
during a day is there more reabsorption or filtration?
filtration exceeds absorption by 2-4 litres
how is excess fluid returned to the circulation?
lymphatic system
what is Oedema?
accumulation of fluid in interstitial spaces
what is the problem with pulmonary oedema?
causes less gas exchange as the fluid increases the diffusion distance
what is the main physiological cause of Oedema?
raised venous pressure
what can pulmonary oedema be a sign for?
left heart failure
what can peripheral oedema be a sign for?
right heart failure
how does heart failure effect the Frank-Starling curve?
shifts it right (even with treatment)
stroke volume is decreased
what clinical exam findings suggest pulmonary oedema?
some shortness of breath
crepitations heard on auscultation if lung bases
CXR shows haziness in perihilar region
what is the definition of Pulmonary Oedema?
accumulation of fluid in the interstitial and intra-alveolar spaces
what biological things can cause Oedema?
lymphatic insufficiency
changes in capillary permeability (eg due to inflammation), reduced plasma osmotic pressure
