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Edexcel GCSE Biology · 1BI0
Edexcel 1BI0 · 7.21B Check the specification (PDF) (opens in a new tab)
Healthy kidneys remove waste substances, including urea, from the blood and help keep the body's water content balanced. In kidney failure, they can no longer do this sufficiently. Wastes may build up and water balance may be disturbed. Two treatments are , which does some of the kidneys' filtering work, and a , which provides a working kidney from a donor.
During kidney dialysis, blood passes through a dialysis machine. The blood and dialysis fluid are kept apart by a partially permeable membrane. Waste substances such as urea pass out of the blood into the dialysis fluid, and excess water can be removed. The treated blood is returned to the person. This helps restore the blood's composition and the body's water balance, but it does not make the failed kidneys work again.
Dialysis can allow a person to live in good health, but it must be carried out regularly, either through hospital visits or using a machine at home. Possible problems include infection or low blood pressure. These continuing demands matter when comparing dialysis with a transplant.
In dialysis, a partially permeable membrane separates blood from dialysis fluid while waste substances and excess water are removed from the blood.
A kidney transplant is an operation in which a healthy kidney donated by another person is given to someone with kidney failure. A donor may be living or may have died. Because a person can live with one functioning kidney, a living person may be able to donate one. If the transplant works, the donated kidney takes over the filtering role and the recipient may be able to live a normal life without regular dialysis.
Transplantation depends on finding a suitable donor kidney, and there may be a wait because too few are available. Doctors match donor and recipient tissues to reduce the risk of rejection, when the recipient's immune system attacks the donated kidney. The recipient needs immunosuppressant drugs to reduce this risk. Surgery may not be appropriate for someone too weak to undergo it. Unlike dialysis, a successful transplant can provide continuing kidney function, but it brings the demands and risks of surgery, matching and preventing rejection.
A machine removes urea and other wastes from the blood; blood and dialysis fluid are separated by a partially permeable membrane. It helps restore water balance but must be repeated. It can involve regular hospital visits or a machine at home, with risks including infection and low blood pressure.
A healthy donated kidney is provided by an operation and can restore continuing kidney function. A suitable donor may be hard to find. Tissue matching reduces rejection risk, and the recipient needs immunosuppressant drugs. Surgery may not suit a person who is too weak.
For a question asking about treatments, describe both dialysis and kidney transplantation, then link each treatment to its consequences or requirements.
Do not say dialysis cures kidney failure: it removes wastes from the blood, but treatment must be repeated.
A donated kidney must be suitable for the recipient; explain rejection risk and the need for immunosuppressant drugs.
It can see this note and what your specification asks for.
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Last updated
Kidney failure
A condition in which the kidneys can no longer remove enough waste substances, such as urea, from the blood or regulate its water content adequately.
Kidney dialysis
A treatment that uses a machine to remove waste substances and excess water from a person's blood when their kidneys cannot do so sufficiently.
Partially permeable membrane
A barrier that allows some substances to pass through but prevents others from passing through.
Kidney transplant
An operation in which a healthy kidney from a donor is placed in a person whose kidneys have failed.
Rejection
A response in which the recipient's immune system attacks a transplanted organ because it recognises it as different from the body's own tissues.
Put your knowledge into practice — try past paper questions for Biology
Kidney failure
A condition in which the kidneys can no longer remove enough waste substances, such as urea, from the blood or regulate its water content adequately.
Kidney dialysis
A treatment that uses a machine to remove waste substances and excess water from a person's blood when their kidneys cannot do so sufficiently.
Partially permeable membrane
A barrier that allows some substances to pass through but prevents others from passing through.
Kidney transplant
An operation in which a healthy kidney from a donor is placed in a person whose kidneys have failed.
Rejection
A response in which the recipient's immune system attacks a transplanted organ because it recognises it as different from the body's own tissues.