homeostasis

• what is homeostasis?

  • maintenance of a constant internal environment
• what happens with water loss on a hot day or exercising?

  • produce lots of sweat
  • less urine produces - more concentrated - deep colour
  • lose more water through your breath when exercising because you breathe faster
• what happens with water loss on a cold day or no exercise?

  • not much sweat produced
  • more urine produced = pale colour - more dilute
• what happens when you are too hot?

  • lots of sweat produced - evaporates - transfers energy from skin to environment to cool you down
  • vasodilation takes place (blood flow near surface)
  • hairs lie flat
• what happens when your cold?

  • very little sweat produced
  • vasoconstriction (less blood flow near surface = less energy transferred to surroundings)
  • shivering - increases rate of respiration - transfers more energy to warm body
  • hairs stand to trap insulating layer of air -helps keep warm
• why can smaller organisms cool down quicker?

  • smaller organisms have bigger SA:VOL ratio - can gain or lose heat faster because there is more area for heat to transfer across
  • lose body heat more easily in hot climates and reduce chance overheating - very vulnerable in cold environments
  • smaller SA:VOL ratio - can gain or lose heat more slowly - less area for heat to transfer across
  • good in cold conditions and poor in hot conditions