biological rhythms

• endogenous pacemaker

  a factor that is inside the body that tells us when to sleep
• what is an example of an endogenous pacemaker

  the SCN located near the hypothalamus in the brain
• what has been used to show the effect of the SCN/endogenous pacemakers on sleep

  animal studies
• how did decoursey et al study the effect of endogenous pacemakers

  • they removed/destroyed the SCN connections of 30 chipmunks
  • returned them to their habitat
  • observed them for 80 days
  • found that their sleep wake cycle had disappeared and many were killed by predators due to this disruption
• what hormone is an example of an endogenous pacemaker

  melatonin

  • reduces heartrate during the night
• what is an exogenous zeitgerber

  an external factor that effects sleep
• what study proves the effect of exogenous zeitgebers on sleep cycles

  campbell and murphy
• campbell and murphy exogenous zeitgeber study procedure

  • 15 participants were woken multiple times and light was shone at the back of their knees
  • found that sleep cycle changed
  • shows that we have receptors in our skin for receiving light which is an exogenous zeitgeber
• what is likely to be developed if circadian rhythms are disrupted

  • heart disease
  • depression
• whats an infradian rhythm

  a rhythm that takes longer than 24 hours
• what are biological rhythms

  patterns of changes in the body over cyclical time periods
• what is a circadian rhythm

  a rhythm that follows a 24hr cycle
• whats an ultradian rhythm

  a rhythm/cycle that takes less than a day
• examples of circadian rhythms

  heart rate

  metabolic activity

  sleep wake cycle

  body temp
• exogenous zeitgebers examples

  dark-light cycle

  dinner

  other people

  tv

  time