Homeostatic Responses

• Homeostasis is the maintenance of a stable internal environment within fixed/ narrow limits.
• Why is it important to maintain a stable temperature and pH?

  Enzyme activity will be affected by changes in pH and temperature.
• Why is it important to maintain a stable level of glucose?

  • Changes in the concentration of glucose will affect the water potential pf the blood causing cells to swell or shrink.
  • Provide a constant source of glucose for homeostasis.
• All Homeostatic mechanisms have the same common features:

  • Set Point / Normal Level
  • Receptors that detect the change
  • A co-coordinator that monitors inputs from receptors and sends electrical impulses or hormones to the effectors.
  • Effectors that cause a corrective response back to the set point.
  • Negative feedback loop.
• Hormones are produced by endocrine glands that are secreted into the blood stream.

  The hormones are carried in the blood plasma to target cells which have receptors on their surface with a complementary shape to the hormone.
• Hormonal Responses:

  • Slow
  • Long-duration
  • Widespread