Quote from RNRabbit2be75
I'm having a difficult time understanding this....thanks in advance....
From inside the capillaries, think of hydrostatic pressure as the 'pushing force', pushing the fluid out of the capillaries. It's the result of the actual pressure of the fluid on the capillary walls.
Oncotic pressure, also called 'colloid osmotic pressure', is the 'pulling force', pulling fluids from the surrounding tissue into the capillaries. It's the result of a difference in the concentration of solutes in the fluid inside the capillaries as opposed to outside them, because water will naturally seek a state of balance in the concentration of solute (particles).
As fluid leaves the capillaries as a result of hydrostatic pressure, albumin and other large proteins cannot pass through the capilary walls. This results in a greater concentration of solutes inside the capillaries as opposed to outside of them, and the oncotic pressure rises, pulling more water into the capillaries in order to balance the solute concentration.
Whenever hydrostatic pressure is greater than oncotic pressure, fluid will leave the capillaries, whenever the onctoic pressure is greater than the hydrostatic pressure fluid will enter the capillaries.