Reasons why body temperature can INCREASE:
• Being in a warm environment because the external heat up the blood in your body
• Exercising because respiration occurs, which releases energy by using up food stores in the body.
• When you have a flu or a virus, because pyrogens (chemicals which regulate body temperature) builds up in the hypothalamus (a section of the front of the brain).
Reasons why your body temperature can DECREASE:
• It can decrease when you are too hot, because your body releases sweat from the sweat glands on your skin which evaporates. Also, your blood vessels become narrower (a process called vasoconstriction) so that it lose less heat and is further away from the surface of the skin.