Colloid Osmotic Pressure

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The colloid osmotic pressure (KOD) (also oncotic pressure) is the proportion of the osmotic pressure that is caused by the colloids of a solution.

In human body fluids, such as. B. the blood plasma , the colloid osmotic pressure is mainly determined by proteins such as albumin or globulins . It is essential for maintaining the plasma volume, since in humans the vascular wall is usually well permeable for small molecular plasma components (e.g. ions), whereby the osmotic pressure difference would almost always be balanced. Since the endothelium is differently permeable to colloids, a pressure is created in the blood vessel to the plasma (intravascularly), which counteracts the natural hydrostatic pressure to the extravascular direction. The difference between these pressures (hydrostatic pressure - colloid osmotic pressure) is called the effective filtration pressure.


  • Robert F. Schmidt (ed.): Physiology of humans . 30., rework. and updated edition. Springer, Heidelberg 2007, ISBN 978-3-540-32908-4 , pp. 49 .

Individual evidence

  1. ^ R. Klinke, H. Pape, A. Kurtz & S. Silbernagl, Physiologie (6th edition), Georg Thieme Verlag. Stuttgart, 2010. ISBN 978-3-13-796006-5 , pp. 195 & 893-894.