Osmoregulation & The Kidney - Kidney Failure and Dialysis (GCSE Biology)

Kidney Failure and Dialysis

Renal Dialysis

Kidney Failure

• Kidney failure leads to a build up of toxins. When the kidney fails, it can no longer remove waste products from the body. This has dire consequences, as it could cause a build up of toxins in the body.
• Humans may need treatment for kidneys. Humans can usually survive with one functional kidney, however once both kidneys are impaired, intervention is required. Kidney treatment can come in different forms, such as kidney transplant or kidney dialysis.

Dialysis Machines

The current standard treatment is called dialysis. Dialysis involves being attached to a machine that artificially filters your blood outside of your body and it aims to balance salt and glucose concentrations.
Dialysis works by the following method:

1. Unfiltered blood is taken from the human. Dialysis works by taking unfiltered blood from the arm. This blood is then mixed with thinning agents, in order to stop clotting form occurring.
2. The blood is filtered in a dialysis machine. The blood then enters the dialysis machine. The machine contains a circuit for the blood, and a surrounding dialysis fluid. There is a semi-permeable membrane separating the blood from the dialysis fluid. This keeps the conditions similar to the nephron.
3. Waste products pass from blood to dialysis fluid. Waste products such as ions, water and urea pass into the dialysis fluid from the blood. Glucose levels are not transported to keep the required level for respiration.
4. A countercurrent system is used. Both fluids (blood and dialysis fluid) flow in opposite directions. This is known as countercurrent flow, which aids diffusion as it keeps the concentration gradient going. For example, it maintains a high concentration of urea in the blood, and a low concentration of urea in the dialysis fluid, so that urea is always moving out of the blood.

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Negatives of Dialysis

Patients are often kept on dialysis until a working kidney is ready for transplantation. Dialysis is not usually a long term solution because it has many negatives:

• Painful – dialysis is a painful process that takes a lot of time and has a

notable impact on quality of life.