Fluid Balance at the Capillary Level

Question 1

fluid balance at the capillary relies on a balance between what 2 opposing forces?

Answer 1

the pushing force of hydrostatic pressure and the pulling force of oncotic pressure

Question 2

how does the capillary hydrostatic pressure “push” work?

Answer 2

at the ARTERIAL end of the capillary, hydrostatic pressure is higher than oncotic pressure in the capillary so fluid gets pushed into the interstitial space

Question 3

how does the capillary colloidal osmotic pressure “pull” work?

Answer 3

towards the venous end of the capillary, much fluid has moved to the interstitial space, leaving the solutes (plasma proteins) behind
- this creates higher capillary osmotic pressure which pulls fluid from the interstitial space back to the vessel

Question 4

how does fluid get pulled into the interstitial space?

Answer 4

some particles such as glucose and electrolytes move from vessel into the interstitial space an create interstitial colloidal osmotic pressure, pulling some fluid into the interstitial space

Question 5

where is excess interstitial fluid taken up into?

Answer 5

the lymphatics and returned to central circulation

Question 6

what is fluid balance determined by?

Answer 6

push and pull of fluids across the semi permeable capillary membrane