Homeostatic Adaptations

• Set Point 


  The optimal value for an internal variable
• Zone of Physiological Stress

  Zone that's outside of the optimal range but inside tolerance range - not optimal but survival is possible
• Optimum Range 


  The narrower range within an organism's tolerance range for a particular factor at which the organisms functions best
• Tolerance Ranges

  • each organism has set ranges within which they can tolerate the temperature, water balance, and different levels of organic and inorganic matter (tolerance ranges)
  • organisms can survive change in a factor if it's within the tolerance range
  • if an internal environmental factor goes outside of the tolerance range, it may be fatal
• Internal Environmental Factors

  • temperature: as temperature increases, so does the rate of the reaction - at high temperatures, enzymes can denature as the shape of the active site changes due to bonds breaking
  • nitrogenous waste: different enzymes work best at different pH's - if pH deviates too far from optimum, enzymes can denature as bonds are broken and the shape of the active site is changed
  • gases
  • salts
  • water
• Adaptations

  Features and strategies used by an organism to help them survive a particular environment
• Physiological Adaptations

  • involuntary changes in functioning - related to how an organism, system, organ, tissue or cell functions
  • eg. breathing rate, shivering, sweating, urination, hibernation
• Structural Adaptations

  • determined by genome - related to an organism's shape and size
  • eg. fur thickness, body colouring, SA:V ratio
• Behavioural Adaptations

  • voluntary changes in behaviour - related to how an organism acts
  • eg. drinking, basking in the sun, changing amount of physical activity