warming mechanisms

• vasoconstriction of blood vessels that supply skin capillaries

  • smaller amount of blood flowing through skin capillaries so reduced heat loss via radiation
  • muscles in arterioles walls constrict
  • instead blood is diverted through shunt vessels deeper in skin
  • less heat lost via radiation to the environment
• boosting metabolic rate

  • metabolic reactions mainly exothermic- provides warmth
  • when cold- thyroxine is produce- increased basal metabolic rate= increase heat
  • adrenaline also increases metabolic rate and releases more heat
• shivering

  • shivering is a reflex due to a decrease in core body temperature
  • muscles are effectors- contracting regularly and rapidly
  • respiration and metabollic processes are required for these contractions which releases energy as a by product=heat
• erection of hairs(heat retention)

  • erector pili muscles contract, hairs stand up
  • forms an insulating layer over the surface of skin as hairs trap air
  • stops heat loss via radiation
• less sweating(heat retention)

  • reduces heat loss via evaporation