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Functions in your body to keep the internal environment as constant
as possible and working effectively.
Removing Waste Products
Waste Products: Carbon dioxide (produced by respiration, leaves the
body via the lungs when we breathe out)
Urea (produced by the liver in the breakdown of excess
amino acids, removed by the kidneys in the urine,
which is temporarily stored in the bladder)
Water and ions (enters body through food and drink)
Produced: Waste product of respiration.
Where: In the cells
NB every cell in your body respires, so every cell must
Removed because: Dissolved carbon dioxide produces an acidic
Must be removed because if it remained in the
cytoplasm of the cells, the pH would become acidic.
How: Transported to the lungs and breathed out.
Produced: When excess amino acids are broken down
Where: In the liver
Removed because: Poisonous to the body.
If allowed to build up, eg if blocked by gall stones, it
can cause a person to have a yellowish tinge to the skin.
How: Passed into the blood and transported to the kidneys, where it is
filtered from the blood. Removed in the urine with excess water
and salt. Urine leaves the kidneys and is stored in the bladder, ready
to be excreted.
Water and Ions
Produced: Enter body when we eat and drink
Removed because: Too much water and ion can cause damage to the
cells by too much moving in or out of them.
How: Water - through breathing, sweating and in urine
Ions - through sweat and in urine
Controlling Body Temperature
MUST BE KEPT AT 37°C. This is because this is the temperature that
enzymes work best at.
Body temperature is controlled and monitored by the
thermoregulatory centre in the brain. This centre has receptors
sensitive to the temperature of blood flowing through the brain.
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Temperature receptors in the skin send impulses to the centre giving
it information about the skin temperature.
To cool down: Sweat glands release more sweat.
This cools the body while the sweat evaporates from
the skin using the body's heat. More water is lost when it
is hot, and more water has to be taken in (through food
and drink) to balance this out.
Hair (and fur in animals) lie flat against the skin.
To reduce heat loss (i.e.…read more