Endogenous Pacemakers and Exogenous Zeitgebers

• Endogenous Pacemakers:

  • Internal body clock that regulate many of our biological rythyms.
  • E.g influence of the suprachiasmatic nucleus (SCN).
• Endogenous Pacemakers (sleep/wake cycle):

  The Suprachiasmatic Nucleus

  • Tiny bundle of nerve cells located in the hypothalamus in each hemisphere of the brain.
  • A primary endogenous pacemaker and is influential in maintaining circadian rhythms e.g sleep/wake cycle.
• Endogenous Pacemakers (sleep/wake cycle):

  The Suprachiasmatic Nucleus

  • Nerve fibres connected to the eye cross in an area called the optic chiasm on their way to the left and right visual area of the cerebral cortex.
  • The SCN lies above the optic chiasm. Recieves information about light. Contrinues when our eyes are closed, enables the biological clock to adjust to changing patterns of daylight when we are asleep.