Thermoregulation in endotherms

• Endotherms= use heat produced internally to maintain body temperature.
• Detecting temperature changes

  • Peripheral temperature receptors in the skin.
  • Temperature receptors in hypothalamus.
  • Impulses from thermoregulatory centre pass to effectors In the skin and muscles.
• Vasodilation

  = Cooling down.

  • Arterioles supplying the skin dilate.
  • The arteriovenous shunt vessels constrict.
  • This increases the flow of blood to our skin.
  • Which increases the transfer of energy from our skin to the environment via radiation.
• Vasoconstriction

  =Warming up

  • Arterioles supplying the skin contract.
  • Arteriovenous shunt vessels dilate.
  • This decreases flow of blood to our skin, so little heat Is radiated.
• Cooling down

  • Vasodilation
  • Increased sweating= as sweat evaporates from the surface of the skin, heat Is lost, cooling the blood below the surface.
  • Erector pili muscles in the skin relax.
• Warming up

  • Vasoconstriction
  • Decreased sweating
  • Erector pili muscles in the skin contract= traps an insulating layer of air and so reduces cooling through the skin.
  • Shivering= involuntary contracting and relaxing of large voluntary muscles. The metabolic heat from the exothermic reactions warm the body.
  • Minimise their SA:V ratio