kolloidiosmottinen

Kolloidiosmoottinen paine, also known as oncotic pressure, is a specific type of osmotic pressure. It is exerted by large molecules, primarily proteins, dissolved in a fluid that cannot readily cross a semipermeable membrane. In biological systems, the most significant contributors to colloid osmotic pressure are plasma proteins, such as albumin, found in blood plasma.

This pressure plays a crucial role in fluid balance within the body. Within blood vessels, the colloid osmotic pressure exerted by plasma proteins tends to draw water from the surrounding interstitial fluid back into the capillaries. This counteracts the hydrostatic pressure, which forces fluid out of the capillaries. The balance between these two pressures, hydrostatic and colloid osmotic, determines the net movement of fluid across the capillary walls.

Disruptions to normal colloid osmotic pressure can have significant physiological consequences. For instance, a reduction in plasma protein concentration, often seen in conditions like liver disease or malnutrition, leads to a decreased colloid osmotic pressure. This can result in an accumulation of fluid in the interstitial spaces, causing edema (swelling). Conversely, abnormally high protein concentrations can also disrupt fluid balance. Understanding colloid osmotic pressure is therefore essential in fields like medicine and physiology for comprehending fluid dynamics within living organisms.