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Yousef Biopsych > Endogenous Pacemakers and Exogenous Zeitgebers > Flashcards

Endogenous Pacemakers and Exogenous Zeitgebers Flashcards

1
Q

What are endogenous pacemakers?

A

Internal body clocks that regulate biological rhythm

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2
Q

What is the superchiasmatic nucleus (SCN)?

A

Bundle of nerve cells

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3
Q

Where is the SCN located?

A

Hypothalamus

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4
Q

What is the SCN linked with?

A

The sleep/wake cycle

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5
Q

What is the SCN connected to?

A

Optic chiasm

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6
Q

What does the SCN receive?

A

Light directly when the eyes are closed

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7
Q

Which two psychologist researched into the sleep/wake cycle?

A
  • Decoursey et al

- Ralph et al

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8
Q

What did Decoursey et al (2002) do?

A
  • Destroyed SCN connection in 30 chipmunks

- Returned them to natural habit and observed

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9
Q

What did Decoursey et al (2000) find?

A

Sleep/wake cycle disappeared and majority killed after 80 days

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10
Q

What did Ralph et al (1990) do?

A
  • Bred hamsters with 20 hour sleep/wake cycle

- SCN of mutant hamsters transplanted into normal hamsters

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11
Q

What did Ralph et al (1990) find?

A

Normal hamsters developed a 20 hour sleep/wake cycle

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12
Q

What is the SNC an example of?

A

Endogenous pacemaker

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13
Q

What are the three examples of endogenous pacemaker?

A
  • SCN
  • Pineal gland
  • Melatonin
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14
Q

How is SCN linked to the pineal gland and melatonin?

A

SCN passes information on day length to pineal gland which increases secretion of melatonin during the night

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15
Q

What does melatonin induce?

A

Sleep

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16
Q

When is melatonin inhibit?

A

During periods of wakefulness

17
Q

What are the different factors which influence the sleep/wake cycle?

A
  • Endogenous pacemakers

- Exogenous zeitgebers

18
Q

What are exogenous zeitgebers?

A

External cue which may affect biological rhythm i.e reset the biological clock

19
Q

What is the resetting of the biological clock is a process known as?

A

Entrainment

20
Q

What important exogenous zeitgebers are involved in the sleep/wake cycle?

A
  • Light

- Social cues

21
Q

Who studied into the effect of light on the sleep/wake cycle?

A

Campbell and Murphy (1998)

22
Q

What did Campbell and Murphy (1998) do?

A
  • Woke 15 participants at various times

- Shone a light on backs of their knee

23
Q

Why did Campbell and Murphy (1998) shine a light on the backs of their participants knees?

A

Produces a deviation in the sleep/wake cycle

24
Q

Does the detection of light just occur by the SCN?

A

No - skin receptors can also detect light

25
Q

How has social cues shown to be an important influence on sleep/wake cycle?

A
  • Babies have set schedules can set sleep/wake cycle (normally really random in newborns)
  • Adapting to local time when travelling for eating and sleeping resets circadian rhythm (tackles jet lag)
26
Q

Is SCN the only endogenous pacemaker?

A

No

27
Q

What are other endogenous pacemakers?

A
  • Lungs
  • Liver
  • Skin
  • Pancreas
28
Q

Why is studies into SCN limiting?

A

As ignores the important and the independence of the effects of other endogenous pacemakers

29
Q

Who showed the independence of the liver to the SCN?

A

Damiola et al (2000)

30
Q

What did Damiola et al (2000) find?

A

That altering feeding pattern altered circadian rhythm of the liver of up to 12 hours

31
Q

Are you able to generalise animal studies to humans?

A

No

32
Q

What are the issues when studying SCN and animal studies?

A
  • Ethical issues

- Great harm and potential risk when returned back to habitat

33
Q

How may the influence of exogenous zeitbegebers be overstated?

A

People who are born bind show normal sleep/wake cycle, only needed to take sedatives in the morning to align with 24-hour world (Miles et al. 1977)

34
Q

What was a limitation to Campbell and Murphy (1998) method?

A
  • Hasn’t been replicated

- Some light exposure to participants eyes (confounding variables)

35
Q

What may studies have ignored when studying into exogenous zeitebegers?

A

How different exogenous zeitbegers interact and influence the sleep/wake cycle (reductionist)

36
Q

What is the collective problem between the research in to exogenous zeitebegers and endogenous pacemakers?

A
  • That it is hard to separate the two when conducting research into just one
  • Why do researchers try to separate the two functions when they work together

Yousef Biopsych (9 decks)

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