B2 - Homeostasis

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  • Created by: Nadeem P
  • Created on: 07-01-10 22:47
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Homeostasis ­ How do our bodies keep internal conditions constant?
How do our bodies keep internal conditions constant?
Which conditions does our body have to control?
Water content
Ion content
Blood sugar level
Why do these conditions need to be controlled?
Water and ion content:
If this is wrong, too much water will move in and out of the cell by osmosis. This will cause damage
to the cell. Water and ions come from our food and drink. When water is lost (e.g. sweat) then the
body must replace this water and this must come from foods and drinks. This is the same with ions.
Blood sugar level:
This is monitored and controlled by the pancreas. The pancreas secretes insulin which converts
glucose into glycogen (insoluble) and thereofre lowers the blood sugar level as it allows the
glucose to pass out from the blood.
Levels of insulin affects what happens in the liver. The pancreas automatically adjusts the amount of
insulin released according to the amount of glucose in our body. This is to ensure that the level of
blood sugar is as close to normal as possible.
If there is too little insulin produced by the pancreas - blood sugar levels will rise to a fatally high
rate. This creates a condition called diabetes.
The temperature should be kept at around 37 degrees C. This is the ideal temperature for enzymes
in the body to work. This is controlled by the nervous system.
Monitoring and controlling happens in the thermoregulartory centre (brain). The skin also contains
temperature receptors.
Removing waste products:
Two waste products need to be removed: Carbon dioxide and Urea.
Carbon dioxide is produced by respiration - removed by lungs
Urea produced in liver after it breaks down amino acids - removed by kidneys (transferred
to the bladder before it is released)
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What is the thermoregulatory centre? What does it do?
This is part of your brain. It monitors the body temperature and does its best to keep the body at
the best temperature (37 degrees C).
When the body temperature is too high:
Blood vessels (in skin) dilate which increases heat loss. Sweat glands produce sweat and when it
evaporates it cools the skin.
When the body temperature is too low:
Blood vessels (in skin) constrict which reduces the heat loss.…read more

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Problems may occur if a person smokes
Inhaled Insulin:
No injections (some are afraid of needles)
In tests, these doses produces a consistent concentration of insulin
Research is still being carried out - safe to use?
Timing of doses is hard to work out
Potential to cause lung cancer
Page 3 of 3…read more


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