Coordination

• Organisms need to detect and respond to changes In their internal and external environments.
• Changes in internal environment

  -blood glucose concentration

  -internal temperature

  -water potential

  -cell pH
• Changes in external environment

  -humidity

  -external environment

  -light intensity

  -new or sudden sound
• React through electrical responses (via neurones) and through chemical responses (via hormones)
• Cell signalling 


  =one cell releasing a chemical which has an effect on another cell( target cell)

  • transfer signals locally, signal used is a neurotransmitter
  • transfer signals across large distances using hormones
• Stimulus- receptors detect stimulus and convert them into an electrical signal- sensory neurone- relay neurone- motor neurone- effector- response
• Homeostasis 


  = regulation of internal conditions of a cell