Biological Rhythms Flashcards
What are biological rhythms & what are the 3 types?
A pattern in physiological/psychological processes which repeats itself over a specified period of time & the 3 types are:
- Circadian Rhythms
- Infradian Rhythms
- Ultradian Rhythms
What are circadian rhythms?
They repeat once every 24hrs, e.g. the sleep/wake cycle, which typically follows a regular 24hr cycle. Research has shown that endogenous pacemakers such as neural mechanisms & hormones control the sleep/wake cycle within the brain. The regularity of sleeping & waking is maintained by exogenous zeitgebers, e.g. light/alarm clocks which entrain the sleep/wake cycle. Studies often investigate the free running of endogenous pacemakers through the use of isolation studies, which involve ps having no access to external cues that may reset the circadian rhythms.
What are endogenous pacemakers?
Internal biological body clocks within an organism that regulates its biological rhythms, e.g. hormones & neural mechanisms.
What are exogenous zeitgebers?
External cues/time givers that can affect/entrain (brings the rhythm more in sync w/ the external factors) an organism’s biological rhythm.
What are infradian rhythms?
They are longer than 24hrs & so repeat less than once every 24hrs, e.g. the human menstrual cycle, which has a typical duration of 28 days. The menstrual cycle is internally controlled by endogenous pacemakers (e.g. hormones), which are coordinated by the pituitary gland. The menstrual cycle may also be influenced by external zeitgebers such as pheromones, which are biochemical substances that are released in the air rather than the bloodstream. The release of these pheromones may facilitate the synchronisation of menstrual cycles b/w different women.
What are ultradian rhythms?
They are shorter than 24hrs & so repeat more than once every 24hrs, e.g. the cycle of sleep stages, which involves NREM & REM sleep during a typical night. Whilst sleeping, we usually experience 5 sleep cycles, each of which lasts about 90 minutes. During each cycle, a person undergoes a period of NREM sleep lasting approximately 80 mins, followed by a period of REM sleep lasting around 10 mins. The brain stem is the endogenous pacemaker that acts as a switching mechanism b/w REM & NREM sleep & stages of sleep whilst exogenous factors such as alcohol, caffeine & exercises are external factors that can influence the timing of the cycle.
