Why do some people need to use a dialysis machine? Explain the principle involved in it. (AS1)

Some people need to use the dialysis machine as the kidneys of those people are unable to work efficiently due to some diseased condition or kidney damage. Thus to rid the body of nitrogenous wastes the dialyzer is used which works as an artificial kidney.

The principle behind the working of the dialyzer is diffusion of solutes and ultrafiltration of fluid across a semi-permeable membrane. This is the same principle followed by the nephrons of the kidney for the production of urine.