d49b36f6_BiologyMad_A_Level_Biology__Response_to_low_temperature
[Effector] Erector pili muscles in skin (attached to skin hairs) [Response to high temperature] Muscles relax, lowering the skin hairs and allowing air to circulate over the skin, encouraging convection and evaporation. [Response to low temperature] 
Muscles contract, raising skin hairs and trapping an insulating layer of still, warm air next to the skin. Not very effective in humans, just causing “goosebumps”.
BiologyMad A-Level Biology
Response to low temperature