Homeostatis - AQA GCSE Biology Additional

Revision notes on homeostatis.

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  • Created on: 03-01-12 14:53
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For your body to work properly, the conditions inside your body
must stay constant as possible. This is done through homeostasis
Removing waste:
No matter what you are doing your cells are constantly producing
waste from chemical reactions. Some of these waste products are
poisonous and must be removed from your body.
Carbon Dioxide:
Carbon dioxide is produced in cellular respiration. If it remains
dissolved in the cytoplasm of your cells, it would affect the pH,
because dissolved Carbon Dioxide is acidic. A change in pH
causes the enzymes to become denatured and stop working.
So the carbon dioxide is moved out of your cells and into your
blood stream. Your blood carries it back to your lungs where you
breathe it out.
It is produced in liver when excess amino acids are broken down
and converted into urea. Urea is passed into your bloodstream
and then filtered out by your kidneys. It is removed in your urine
with excess water and salt. It is stored in your bladder.
Maintaining body balance:
Water and ions enter your body when you eat or drink. They are
carefully controlled so not to cause damage to your cells.
Water is lost through sweating, breathing and urine. Ions are lost
through sweat and urine.
If the water and ion content in your body are wrong then to much
water will move in or out of your cells (See Osmosis).
Controlling body temperature:

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It is vital that your body temperature remains around 37ºC,
because this is the temperature at which your enzymes work the
Your skin temp can vary enormously but your core temp must be
kept stable. If you are a few degrees out, then your enzymes will
not function properly.
The Thermoregulatory Centre in the brain controls the temperature
in your body. The centre contains receptors which are sensitive to
temperature changes as they monitor the temp of the blood
flowing through the brain.…read more

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Glucose is needed for respiration so it is important that levels are
kept constant. It is controlled by hormones produced in the
The pancreas:
It is a small pink organ found just under your stomach. It monitors
you glucose levels and controls them using Insulin and Glucagon.
When your level of glucose is above a certain point, then insulin is
released.…read more


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