Fluid shift across the Capillary wall and oedema Flashcards
What does blood flow in the capillary depend on
Contractile state of the arterioles
What are terminal arterioles
regional blood flow to capillary bed (CB) in most tissue
What are precapillary sphincters
regulate blood flow to capillary bed in a few tissues
What does fluid movement follow
Its pressure gradient
What does the movement of gasses and solutes follow
Ficks law of diffusion (against concentration gradient)
What do lipid soluble substances go through
Endothelial cells
What do water soluble (hydrophilic) substances go through
water filled pores
Can large molecules cross the capillary wall
Generally not
What is the trans capillary fluid flow
Passively driven by pressure gradient across the capillary wall (Stirling forces)
What is capillary hydrostatic pressure
The pressure exerted by blood in the capillaries against the capillary wall, forces fluid out of the capillary
What is the Capillary osmotic pressure
The pressure exerted by proteins in the blood in the capillary, pulls fluid into the blood
What is interstitial fluid hydrostatic pressure
The pressure of fluid in the interstitial , forces fluid back into capillary
What is interstitial fluid osmotic pressure
The pressure of the proteins in the interstitial, pulls fluid out of the capillary
Starling force favours filtration at the … end and reabsorption at the … end
Arteriolar end
Venular end
what do the signs in this equation stand for * NFP = (PC + pi) - (pC + Pi)
NFP = starling force
PC = hydrostatic pressure in the capillary
Pi = hydrostatic pressure in the interstitium
pC = oncotic pressure in the capillary
pi = oncotic pressure in the interstitium
Is the pulmonary capillary hydrostatic pressure low or high compared to the capillary osmotic pressure
Low - favours filtration
What removes any filtered fluid from the pulmonary capillaries to prevent accumulation of interstitial fluid
Lymphatic drainage
What is an oedema
Accumulation of fluid in interstitial space
What happens in pulmonary oedemas
Diffusion distance increases - gas exchange compromised
What happens in pulmonary oedema
Lung compliance decreases
What are the causes for oedema
Raised capillary hydrostatic pressure
Reduced plasma osmotic pressure
Lymphatic insufficiency
Change in capillary permeability
How does raised capillary hydrostatic pressure lead to an oedema
Arteriolar dilation
Raised venous pressure
Left ventricular failure - Pulmonary oedema
Right ventricle failure - peripheral oedema
Prolonged standing - swollen ankles
What kind of oedema does left ventricular failure lead to
Pulmonary oedema
What are the symptoms of Pulmonary oedema
Shortness of breath
How is pulmonary oedema diagnosed
crepitations in ascultation of lung bases
Chest x-ray shows haziness in perihilar region
What happens to the Renin-angiotensin-sytem in HF and what does that lead to
RAAS is up regulated resulting in more fluid retention
