First 207 words of the document:
People whose kidneys do not function properly die because toxic
substances accumulate in their blood.
Their lives can be saved by using dialysis machines or having a
healthy kidney transplanted.
A healthy kidney produces urine by:
first filtering the blood
reabsorbing all the sugar
reabsorbing the dissolved ions needed by the body
reabsorbing as much water as the body needs
releasing urea, excess ions and water as urine
Sugar and dissolved ions may be actively absorbed against a
People who suffer from kidney failure may be treated either by
using a kidney dialysis machine or by having a healthy kidney
In a dialysis machine a person's blood flows between partially
The dialysis fluid contains the same concentration of useful
substances as the blood. This ensures that glucose and useful
mineral ions are not lost.
Urea passes out from the blood into dialysis fluid.
Treatment by dialysis restores the concentrations of dissolved
substances in the blood
to normal levels and has
to be carried out at
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A kidney transplant enables a diseased kidney to be replaced with
a healthy one from a donor.
However, the donor kidney may be rejected by the immune
system unless precautions are taken.
To prevent rejection of the transplanted kidney:
a donor kidney with a `tissuetype' similar to that of the
recipient is used
the recipient is treated with drugs that suppress the immune
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The patient must undergo
irradiation of the bone marrow
The patient must be kept in
hospital in sterile conditions for
some time after the transplant
There is a shortage of donors
Here is a diagram showing how normal kidneys function:…read more