Final answer:
The difference between colloid osmotic pressure of the plasma and the interstitial fluid is termed oncotic pressure, which is essential for the reabsorption of fluid into the capillaries. It is notably influenced by the blood colloidal osmotic pressure (BCOP) and is higher than the interstitial fluid colloidal osmotic pressure (IFCOP), contributing to osmosis.
Step-by-step explanation:
The difference between colloid osmotic pressure of the plasma and the interstitial fluid is termed oncotic pressure. This oncotic pressure is crucial because it contributes to the movement of fluid from the interstitial fluid back into the capillaries, a process known as reabsorption. Osmotic pressure, which is a form of pressure that is determined by osmotic concentration gradients, draws fluid back into the capillaries when there's a difference in solute-to-water concentrations in the blood and tissue fluid.
The blood colloidal osmotic pressure (BCOP) is created by the concentration of colloidal proteins in the blood, and since these plasma proteins cannot move across the semipermeable capillary cell membrane, it remains in the plasma, resulting in the blood having a higher colloidal concentration and thus attracting water. In contrast, the interstitial fluid colloidal osmotic pressure (IFCOP) is usually very low due to the few proteins it contains.
Overall, the difference in colloidal osmotic pressure between the BCOP and the IFCOP is what accounts for the reabsorption of water from the tissue fluid back into the capillaries.