The Kidneys

Topics: Chronic kidney disease, Immune system, Kidney Pages: 27 (936 words) Published: April 19, 2015
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Waste removal
Several organs are important in removing waste from the body. The lungs remove
carbon dioxide.
The skin provides
a surface for small
amounts of water
and salt to move
out of the body.

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The liver
converts excess
protein into urea.
The kidneys
remove unwanted
substances such
as urea, excess
water and salt.

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What is urea?
Excess amino acids in the body are
broken down by the liver, producing
a waste substance called urea.
This process is important because
it converts toxic ammonia to urea,
which is done using carbon dioxide.
Once formed, urea is transported by the
circulatory system to the kidneys.
The kidneys filter the blood, removing
urea and excess water and salt, which
forms urine. Urine is stored in the bladder
before being excreted from the body.
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What are the different parts of a kidney?

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How does the kidney work?

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Stages in the nephron

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Controlling water content

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Regulating water content

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Analysing urine
Changes in the colour, clarity, pH and the presence of certain substances in urine can help doctors diagnose medical
conditions:
 Protein or red blood cells in
urine can indicate kidney
damage or disease, as these
substances would not normally
filter through the glomerulus.
 Glucose in urine is often an
indication of diabetes. A person
with diabetes will have a high
level of glucose in the blood.
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Which sample?

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What happens if the kidneys fail?
Humans can survive with just one functioning kidney. If both kidneys become diseased or damaged, it can be fatal.
Kidney failure can occur
due to infection, diabetes,
long-term high blood
pressure or damage in an
accident. If left untreated,
urea and other toxins can
build up in the blood,
poisoning the patient.
To counteract this, people with kidney failure can undergo
regular kidney dialysis, or receive a kidney transplant.
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What is dialysis?
Dialysis involves diverting the blood through an 'artificial kidney' machine that cleans it and returns it to the body.
What happens during kidney dialysis?
1. A tube is connected to a vein
in the patient’s arm.
2. The patient’s blood flows along
the tube, into the machine.
3. Inside the machine, the blood is pumped through semipermeable tubes surrounded by dialysis fluid. Dialysis fluid contains sodium, magnesium, calcium chloride and
potassium chloride and sodium acetate, in the same
concentrations as the blood plasma of a healthy person.
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Dialysis machine

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Disadvantages of dialysis
It is difficult to control the
diffusion of substances in a
dialysis machine as well as in
a kidney so people on dialysis
often have to carefully control
their fluid intake and diet.
Dialysis can involve a patient
going to hospital up to three
times a week and being
connected up to the dialyser
for about four hours at a time.
This could have a large
impact on a person’s lifestyle.
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What is a kidney transplant?
Kidney failure can also be treated by giving a patient a kidney transplant. This involves replacing the damaged kidney with
a healthy kidney from a donor.
Healthy organs can come from a living or recently deceased
person. Living donors are often close friends or relatives of the patient.
In the UK there is an organ donor
register. By joining this people agree to
the donation of their organs and tissue
for...
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