A2 Biology: Kidney Failure

If the kidney fails - unable to remove urea - not going through osmoregulation

3 main causes:

• Diabetes mellitus
• hypertension
• infections

Use of dialysis

Dialysis removes waste, salts and excess fluids from the blood by passing over a dialysis membrane. Dialysis membrane is partially permeable and contains the perfect plasma, so it has right amount of glucose, water and other substances but not urea. Urea is passed through into the dialysis membrane by diffusion.

Methods of control:

• Haemodialysis - blood from vein is passed through a machine which contains  artificial dialysis membrane and returns back into the blood. Heparin is added to act as an anticoagulant.

• Peritoneal dialysis - filters the body's abdominal membrane. A permanent tube is implant into the abdomen and dialysis solution is poured in to fill up the space between abdomen wall and organs. Several hours later this solution is drained from the abdomen.

• Kidney transplant - is a major surgery where a kidney from a healthy willing relative donor or a healthy kidney from a deceased person is implanted in and is attached to the blood supply and bladder. The old kidney remains in the body unless it is cancerous or likely to cause an infection. The patient would have to take immunosuppressants for life as the new organ would be treated as a foreign object and this would prevent it from being rejected.