homeostasis

• homeostasis is the maintenance of a constant internal environment within a living organism despite fluctuations in its external and internal environment
• factors controlled in a mammalian body

  • water potential
  • concentration of solutes in blood and tissue fluid
  • temperature
  • pH
  • concentration of oxygen
  • concentration of carbon dioxide
  • blood pressure
• homeostasis is important as enzymes are sensitive so homeostasis keeps fluctuations of temperature, pH and other concentrations minimal so enzymes continue to function at optimum rate
• examples of homeostasis

  • glucoregulation
  • thermoregulation
  • osmoregulation
• negative feedback is a primary mechanism of homeostasis. when there is a change in the internal body a response is triggered to counteract the initial fluctuation.
• parts of a feedback system

  • receptor
  • coordinator
  • effector
• thermoregulation

  • if body temperature rises above 37 temperature receptors in the brain detects the increase
  • hypothalamus sends nerve impulses to arteriole muscle
  • vasodilation
  • body temperature falls
  • fall in body temperature tells thermoreceptors in the brain to stop response
• positive feedback increases the initial change. it is usually harmful
• example positive feedback : hyperthermia

  • body temperature falls
  • enzymes become less active
  • less heat released from reactions
  • temperature continues to fall
• advantages of being endothermic is they are better at controlling enzyme activity than ectotherms