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Preview of Homeostasis

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Tubah Ihsan
Our body needs to maintain homeostasis in order to stay alive. Homeostasis is maintenance of a
constant internal environment in an organism. It ensures that the cells of the body are in such
environment that they can functional normally regardless of external changes.
Homeostasis is important for proper functioning of an organism due to following reasons:
Maintaining constant internal environment means that the reactions can take place at a
constant rate. Enzymes (control biochemical reactions) within cells are sensitive to changes in
temperature and pH. Any changes in these factors, reduces the efficiency of enzymes or
denature the enzyme so they will not be able to work at all.
Maintaining constant glucose concentration to ensure a constant water potential. Any
changes to the water potential of blood and tissue may cause cells to shrink or expand.
Changes in water potential are due to osmosis.
Control mechanism
It involves a series of steps which are:
Set point ­ this is the desired level at which the system works.
Receptor ­ monitors set point and if any deviation it informs the control unit
Control unit ­ it coordinates information from the receptors and sends instruction to the
Effector ­ it brings about changes that are needed to return the system to the set point
Feedback loop ­ return to set point normally creates a feedback loop and it informs the
receptor about the changes that have been bought to the system.
Control of temperature:
Enzymes work optimally at a low temperature and pH, however if the temperature or pH is too low
then they will work less efficiently and so reactions will take place slower. Additionally if the
temperature of pH is too high enzymes may b denatured and therefore the enzyme would stop

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Tubah Ihsan
working altogether. Therefore in order for organisms to survive they have to regulate their
temperature. This process is called thermoregulation.
Animals can control their body temperature by controlling heat gain and heat loss.…read more

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Tubah Ihsan
Conserving and gaining heat in cold environment
Mammals and birds living in a cold environment have evolved genetic adaptations in order to survive.
One of the most important adaptations is to have a body with small surface area to volume ratio.
Heat is produced within the volume and is lost from the surface area. Therefore smaller the ratio
easier it is to maintain high body temperature. That is why animals in colder environment are large
(e.g.…read more

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Tubah Ihsan
Lowering of body hair ­ the hair erector muscle in the skin relax, causing the hair to flatten
against the body. This reduced the thickness of the insulating layer and therefore allows
more heat to be lost to the environment when the internal temp is higher than the external.
Behavioural mechanisms ­ they avoid heat of the day by sheltering in burrows and seeking
out shade to help prevent the body temperature from increasing.…read more


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