The temperature centre
in the brain actually comprises three centers. These are a control
centre that regulates the temperature in the blood, a heating centre
that raises the temperature of the blood when it drops and a cooling
centre that cools the blood when its temperature goes high.
For instance, if the
blood temperature drops significantly, part of the nervous system
gets triggered into action. Some glands send out enzymes to increase
oxidation in the muscles and liver and the internal temperature
increases. Also, the blood vessels of the skin contract, ensuring
that less heat is lost by radiation. Skin glands send out fatty
substances that help hold the body heat in. Heat is conserved by
constriction of the superficial blood vessels.
The responses occur naturally. We shiver when we feel cold .
Shivering is a result of the low blood temperature. When it
happens, the heating centre in the brain causes shivering in order
to produce heat.
What happens when the
blood temperature rises? The cooling centre in the brain takes over.
It causes the superficial blood vessels to dilate and sweating
occurs. Perspiration evaporates easily. When it does, it uses
the excess heat from the body from wherever it is located thus
bringing the temperature from high to normal.