Artificial kidney or Haemodialysis : It is the artificial removal of the nitrogenous wastes from the body. It is used in those patients whose kidney tubules do not function properly so that the metabolic wastes start accumulating in the blood and they need to be eliminated frequently. It can be explained in following points.

1. In the process, the blood of the patient is pumped from one of the main arteries and cooled to 0°C.

2. It is then mixed with an anticoagulant heparin and passed through cellophane tube.

3. This cellophane tube is a semipermeable membrane which allows only small molecules like urea, uric acid, creatinine and mineral ions to pass out but the macromolecules like proteins are not able to pass through it.

Fig. Diagram of Artificial Kidney

4. This cellophane tube is suspended in a salt solution which is isotonic with the blood plasma. Now, as the blood flows through this tube metabolic wastes are filtered out of the blood in the salt solution.

5. The purified blood is mixed with antiheparin to restore its normal coaguability and is then pumped into the body through a vein.