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GCSE Biology · key term
A repeated treatment in which a machine removes waste substances and excess water and ions from a patient's blood.
Used by AQA
Specification 4.5.3.3 · Paper 2
Revise: Treating Kidney Failure: Dialysis and TransplantsDialysis is a mechanical treatment that repeatedly cleans the blood. A kidney transplant places a functioning donor kidney in the body so that it can work continuously. Both address the consequences of kidney failure, but in very different ways.
When explaining urea removal, link the facts in a chain: the dialysis fluid contains no urea, so a concentration gradient exists and urea diffuses across the partially permeable membrane from the blood into the fluid.
Do not say that dialysis fluid contains no glucose or ions. It contains normal concentrations of glucose and useful ions, preventing their net loss; excess ions can still leave the blood.
If asked for a judgement, relate it to the patient. A transplant may offer a better long-term quality of life if a suitable kidney is available, whereas dialysis can sustain someone while they wait or when transplantation is unsuitable.
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