5 homeostasis and response

• homeostasis

  a self-regulating process by which a living organism can maintain internal stability while adjusting to changing external conditions.
• Cells in the body

  • Can only survive within narrow physical and chemical limits
  • Require a constant temperature and pH
  • Require a constant supply of dissolved food and water
• Control systems


  Constantly monitor and adjust the composition of the blood and tissues
• Control systems


  • Include receptors which sense changes
  • Include effectors that bring about changes
• Nervous system


  Brings about fast responses
• Hormonal system


  Brings about much slower changes
• Hormonal coordination


  Particularly important in reproduction since it controls the menstrual cycle
• Understanding of the role of hormones in reproduction

  • Allowed scientists to develop contraceptive drugs
  • Allowed scientists to develop drugs which can increase fertility