Biological Rhythms

• What is a biological Rhythm?


  A biological rhythm is any cyclic change in the level of a bodily chemical or function. 
• 
  

  These can be internal (endogenous) - controlled by the internal biological clock e.g. body temperature cycle. 

  OR external (exogenous) - controlled by synchronising internal cycles e.g. sleep/wakefulness with external stimuli e.g. day/night. These external stimuli are called zeitgebersBiological rhythms are periodic activity, governed by:

  1. Internal biological ‘clocks’ (endogenous pacemakers)
  2. 2. External changes in the environment (exogenous zeitgebers).
• Biological Rhythms governed by?


  These can be internal (endogenous) - controlled by the internal biological clock e.g. body temperature cycle. 

  OR external (exogenous) - controlled by synchronising internal cycles e.g. sleep/wakefulness with external stimuli e.g. day/night. These external stimuli are called zeitgebers.

  Biological rhythms are periodic activity, governed by:

  1. Internal biological ‘clocks’ (endogenous pacemakers)
  2. External changes in the environment (exogenous zeitgebers).
• Types of biological rhythm:

  • Circadian
  • Circannual
  • Infradian
  • Ultradian
• Circadian Rhythm?


  Circadian = Biorhythm with a daily frequency e.g. sleep/wake cycle
• Circannual Rhythm?


  Circannual = Type of infradian rhythm that occurs yearly e.g. seasonal affective disorder 
• Infradian Rhythm?


  Infradian = Biorhythms with a frequency of less than one cycle in 24 hours - less frequently than daily (gap longer than a day) e.g. menstrual cycle. (more than a day to complete)
• Ultradian Rhythm?


  Ultradian = Biorhythm with a frequency of more than one cycle in 24 hours e.g. stages of sleep (occur many times a day)
• Types of biological rhythm & definintions?

  Circadian = Biorhythm with a daily frequency e.g. sleep/wake cycle

  Circannual = Type of infradian rhythm that occurs yearly e.g. seasonal affective disorder 

  Infradian = Biorhythms with a frequency of less than one cycle in 24 hours - less frequently than daily (gap longer than a day) e.g. menstrual cycle. (more than a day to complete)

  Ultradian = Biorhythm with a frequency of more than one cycle in 24 hours e.g. stages of sleep (occur many times a day)