Endogenous pacemakers and exogenous zeitgeibers

Sorry for the abbriviations and combining of words, such as 'ina', there was so much to include and so little space :) I hope this information helps you, I took everything out of a model answer and compressed it into these 16 flash cards. 

  • Created by: Milly
  • Created on: 18-01-14 14:14
What are endogenous pacemakers?
internal factors that drive and influence biological rhythms.
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What is the SCN?
In mammals, the suprachiasmatic nucleus (SCN) is the most important EP and is a small cluster of nerve cells located in the hypothalamus. Its primary focus is to obtain information via the optic nerve about incoming light.
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What is the pineal gland?
The pineal gland also influences the sleep wake biological cycle. The pineal gland contains light sensitive cells, which when stimulated by messages sent via the optic nerve from the SCN, either promote or inhibit the production melatonin(sleep horm)
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Morgan (1995) - A01
bred ‘mutant’ hamsters in which the circadian rhythms were 20hrs. SCN’s of these specifically bred hamsters were transferred into hamsters with normal circadian rhythms, who went onto develop the mutated rhythms after the SCN was implanted.
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Morgan (1995) - A02
Consent and right to withdraw are taken away with the animals not being able to choose whether they participate. Suitability in the way that the complexities of human behaviour are being applied to that of hamsters -Validity issue, unrepresentative
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Kate Aldcroft - A01
25 days in temporal isolation. When she came out her bio clock (C rhythm) was 30 hours but temp rhythm stayed at 24hours.
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Kate Aldcroft - A02
From one person so must be careful generalising but when similar findings find when redone.
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Advantage of research into circadian rhythms
There are enormous health, safety and economic benefits to figuring out how the circadian clock works, because desynchronised body clocks reduce alertness and can lead to major accidents.
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What are Exogenous zeitgebers?
factors that influence biological rhythms in an external way. Our clock is reset every day using cues in the environment, as the seasons change, our biological clock does also.
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What are the main zeitgeibers?
Most dominant of all zeitgeibers, particularly in humans is light; two other common ones are social cues and temperature. Social cues involve meal times, appropriate bed times. temp includes hibernation for animals during the winter months.
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Isolated from natural light to see if exogenous zeitgebers were essential for resetting biological rhythms, however during the experiment he was exposed to a lamp,but at the time of the study itwas assumed it wouldn't be enough to entrain B-rhytms
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Campbell and Murphy (1998)
managed to shift the rhythms by merely shining a light on the back of participant’s knees. Demonstrates the power of artificial lighting and brings up validity issue with Siffre's study and falsifies his idea.
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Synoptic Link - freewill vs. determinism debate
ED&EZ support the determinism side, ina biological and environmental way.EZ-environmentally deterministic&EP-biologically deterministic as they're driven by internalfactors which arebiologically programmed.pre-determined as individuals have no choice
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Synoptic Link - holistic approach to explaining influences over biological rhythms
Takes into consideration environmental and biological factors and focuses on how they interact. The running of the biological clock is a combined endogenous and exogenous exercise
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Synoptic Link - Biological approach
There are a number of strengths with this approach such as; it provides clear predictions, explanations can be easily tested and easily ‘proven’/falsified supporting the claim that psychology is a science.
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Other cards in this set

Card 2


What is the SCN?


In mammals, the suprachiasmatic nucleus (SCN) is the most important EP and is a small cluster of nerve cells located in the hypothalamus. Its primary focus is to obtain information via the optic nerve about incoming light.

Card 3


What is the pineal gland?


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Card 4


Morgan (1995) - A01


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Card 5


Morgan (1995) - A02


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