• Question: how can your body choose its temperature (hot or cold)?

    Asked by oliviaeganx to Damien, Suzi, Tim on 23 Jun 2011.
    • Photo: Tim Fosker

      Tim Fosker answered on 23 Jun 2011:

      Hi @oliviaeganx

      Thanks for a great question!

      The name of the process that we use to keep our bodies in the ideal conditions for survival is called ‘homeostasis’. Humans are called ‘warm-blooded’ because they control their body temperature from inside their bodies, not according to the temperature outside of their bodies. In fact our bodies try to keep our core body temperature about the same all the time.

      When we are two hot we perspire to remove heat through our sweat. Also our arterioles (bigger than capillaries, but smaller than arteries) expand to allow more heat to escape from the surface of the skin, this is called vasodilation.

      When we are too cold we stop perspiring and we raise the hairs on our skin to trap air and help insulate us (that’s why we get goose bumps). We also reduce the size of the arterioles (vasoconstriction – less blood to the surface of the skin means we go paler in colour). Finally, part of the brain called the hypothalamus can send signals to the muscles to start shivering which increases heat in the body.

      I hope that answers your question.

    • Photo: Suzi Gage

      Suzi Gage answered on 23 Jun 2011:

      Hi @oliviarganx

      Tim’s answered this really well. All I would add is that the homeostatic responses are pretty much all controlled by the hypothalamus in the brain. It contains temperature receptors which ‘decide’ whether the body is too hot or too cold, and lead to the responses Tim has mentioned if they discover the body temperature is not correct.

      Hope this helps!

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