Schematic illustration of the functional principle of dialysis, based on renal vessels. Vessel network on water and schematic section of the filtration function. Dialysis is a collective term for laboratory seperation and cleaning methods. In medicine, the term is used for therapeutic methods that remove substances from the blood that belong into the urine. In case of an acute or chronic kidney failure, a hemodialysis is performed, where the blood is cleansed outside of the body by a dialyzer and afterwards returned to the body. This way, the kidney can be detoxified. The basis of dialysis is the principle of the semipermeable membrane, where concentration differences between dissolved particles cause pressure difference, which then causes translocation of the particles that fit trough the pores of the semipermeable membrane. The bottom left of the image shows the red blood cells (erythrocytes), which initially carry green toxins. These are transported through the semipermeable membrane due to the pressure difference. On the other side, they are transported outwards by protein layer, where they dock on the free binding sides of the dialysate. The small blue particles depict water-soluble molecules, that, unlike the (here: round and red) proteins, can cross the semipermeable membrane easily. In case of a peritoneal dialysis, blood purification inside the body, the diaphragm is used as a semipermeable membrane.
