What establishes the capillary colloidal osmotic pressure?

Question

Quizplus · Accepted Answer

Proteins such as albumin are too large to pass through the pores of the capillary. Instead, these proteins remain in the intravascular compartment and exert osmotic pressure, which draws water and small solute molecules back into the capillaries. This plasma colloid osmotic pressure is also sometimes called oncotic pressure. Because these large proteins are negatively charged, they attract (but do not bind) an equivalent amount of cations to the intravascular compartment. These cations have the effect of increasing osmotic pressure within the capillary (Donnan effect).

What Establishes the Capillary Colloidal Osmotic Pressure