When too cold (and need to warm) – VASOCONSTRICTION
- Blood vessels near the surface of the skin constrict (tighten)
- This is so that less heat can be transferred from the blood to surroundings
- Shiver to generate heat
- Little sweat is produced, as sweat cools you
- Body hairs stand on end (perpendicular to your skin) – traps a layer of air which will act as an insulator.
When too hot (and need to cool) – VASODILATION
- Blood vessels near the surface of the skin dilate (widen)
- This is so that more blood can flow near the surface, allowing more heat to radiate into the surroundings
- You produce sweat, and as it evaporates heat transfers from your skin to your surroundings.
- Hairs lie flat to avoid trapping air for insulation
This a paper 2, triple science fact.