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THE EXCRETORY SYSTEM
Getting Rid of Wastes
Urine, blood, kidneys, quarter, urea,
urethra, bladder, process, unwanted,
organs, lungs, urination, excretion, urine,
liver, bladder, Kidneys, blood, heart,
toxic, ureters, urine, kidneys
Excretion may be defined as any process that gets rid of unwanted
products or wastes from the body. The main organs involved in
human excretion are the lungs, the liver and the _kidneys.
If you put your hands on your hips your kidneys are close to where
your thumbs are. You have two of these reddish brown, bean-shaped
organs.
Kidneys play an important role in filtering your blood. About a quarter
of the blood that your heart pumps is sent to your kidneys.
These organs filter about 50 litres of blood each hour. Your kidneys
remove waste products of chemical reactions, like urea, from your
blood. Accumulation of these substances would otherwise be toxic or
dangerous to your body. Other substances like salts and water can
also be removed if they are in excess.
Urine is produced by your kidneys. This watery fluid contains
unwanted substances. Tubes called ureters transport urine from your
kidneys to your bladder to be temporarily stored. As it fills, your
bladder expands like a balloon. It can hold about 400ml of urine.
Urination occurs when urine moves from your bladder through a tube
called the urethra_ and out of your body.
BLOOD, WATER AND URINE
Look at the table below showing a comparison between the substances in the
blood and in the urine. Construct a column graph to compare the quantity of the
substances in the blood and in the urine.
Substance
Water
Proteins
Glucose
Chloride (salt)
Urea
Blue = blood
Orange = urine
Quantity
In Blood
92
7
0.1
0.37
0.03
In Urine
95
0
0
0.6
2
THE EXCRETORY SYSTEM .
Label the diagram below of the excretory system and kidney.
kidney
ureter
bladder
urethra
POSITIONING THE EXCRETORY SYSTEM
In the diagram below draw the excretory system into the human torso below,
making sure you have drawn in the correct position.