• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

PSYA3 - Endogenous pacemakers and Exogenous zeitgebers

Extracts from this document...

Introduction

DISCUSS THE ROLE OF ENDOGENOUS PACEMAKERS AND EXOGENOUS ZEITGEBERS IN THE SLEEP-WAKING CYCLE AND AT LEAST ONE OTHER BIOLOGICAL RHYTHM (25 marks) The sleep-wake cycle is an example of a circadian rhythm. These are rhythms that last for 24 hours. The circadian rhythm may be controlled by endogenous pacemakers (internal innate mechanisms such as the suprachiasmatic nucleus) or/and exogenous zeitgebers (external factors such as the light/dark cycle) A case study of a man who was blind from birth found that he had a 25 hour sleep/wake cycle despite exposure to clocks and radios that acted at time cues. ...read more.

Middle

This shows we use the exogenous zeitgeber light to synchronise our sleep-wake cycle to 24 hours, the natural cycle of day and night. A natural study into residents in the Arctic Circle found that in the summer months when the sun didn't set they still sleep for 7 hours a day. This suggests that there are other factors than light that act as zeitgebers, such as social life and clocks. An Infradian rhythm is a biological bodily rhythm that is longer than a day but shorter than a year. The most obvious example is the female menstrual cycle which may be controlled by hormones or pheromones. ...read more.

Conclusion

This is very similar to the way sleep-wake cycle is affected by light. Case studies such as the blind man and the cave study are not very scientific as they only have one participant. It is hard to control all the variables and you cannot generalise the results. But studies on the sleep-wake cycle and the menstrual cycle all show that the endogenous pacemaker is affected by external zeitgebers. This is an example of nature-nurture interaction, as the innate pacemaker is affected by the environment. This study of endogenous pacemakers is an example of biological reductionism as it explains sleep-waking using biological pacemakers in the brain. As research shows that these can be affected by external zeitgebers, you cannot explain biological rhythms just using biological pacemakers. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Physiological Psychology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Physiological Psychology essays

  1. Sleep and Biological Rhythms revision

    Aschoff Disrupting the biorhythms EPs & EZs are vital for survival, when EZ cues change; our internal clock needs to be readjusted. On average takes 3 days to adjust to a 12 hour shift in time. Artificial light can be moderately successful in resetting circadian rhythm but it takes time

  2. Discuss the role of the endogenous and exogenous factors in biological rhythms.

    The SCN is connected to the retina and it appears that daylight falling on the retina has the action of resetting the SCN in order to keep the sleep-wake cycle in line with night and day.

  1. Endogenous Pacemakers, Exogenous Zeitgebers Essay Plan

    Critical Point 3: This explanation has a flaw. Folkard observed a women for 25 days living in a cave. He found that her temperature rhythm was a 24 hour one, but the sleep rhythm was a 30 hour one.

  2. Discuss the role of endogenous pacemakers and exogenous zeitgebers in the sleep/wake cycle, and ...

    He found that once the SCNâs were replanted, the non-mutant nocturnal hamster began to show mutant diurnal behaviour and vice versa. This shows us that the SCN is a key component in controlling the sleep/wake cycle. This is supported by a similar study conducted by Ralph et al (1990)

  1. Discuss the role of endogenous pacemakers in at least one biological rhythm

    Exogenous zeitgebers are external stimuli which may be rhythmic and act like a prompt, affecting internal rhythms. For example, day length is the dominant EZ as proved by Miles? case study, where light is the dominant cue and the

  2. Endogenous pacemakers vs exogenous zeitgebers

    This is because humans are more complex organisms with different physiology so what affects chipmunks and hamsters may not affect us. As we do not know that systems differ from one animal to the next, we cannot solely rely on findings from animal studies but check any animal findings against research with humans.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work