dialyses

the use of a semipermeable MEMBRANE to separate large and small molecules by selective diffusion. Starch and PROTEINS are large molecules while salts, glucose and AMINO ACIDS are small molecules. If a mixture of large and small molecules is separated from distilled water by a semipermeable membrane, the smaller molecules diffuse into the water, which is itself replenished. This principle is the basis of the artificial KIDNEY , which, because a patient's blood is processed, is known as HAEMODIALYSIS .