Endogenous pacemakers and exogenous zeitgebers Flashcards Preview

A-level Psychology (BP) > Endogenous pacemakers and exogenous zeitgebers > Flashcards

Flashcards in Endogenous pacemakers and exogenous zeitgebers Deck (17)
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1
Q

What does SCN stand for?

A

Suprachiasmatic Nucleus

2
Q

What is the SCN?

A

A tiny bundle of nerve cells located in the hypothalamus in each hemisphere of the brain

3
Q

What is the SCN a type of?

A

One of the primary endogenous pacemakers in the mammalian species and is influential in maintaining security such as the sleep wake cycle

4
Q

Where is the SCN?

A

Nerve fibres connected to the eye cross in an area called the optic chiasm on their way to the visual area of the cerebral cortex and the SCN lies just above the optic chasm and receives information about light from this structure

5
Q

What happens with the SCN when are eyes are closed?

A

It continues enabling the biological clock to adjust to changing patters of day light

6
Q

What was DeCoursey’s research into the SCN?

A

He destroyed the SCN connection in the brains of 30 chipmunks who were returned to their natural habitat for 80 days

7
Q

What were DeCoursey’s results?

A

The sleep/wake cycle for the chipmunks disappeared and by the end of the study a significant proportion had been killed by predators

8
Q

What was Ralph et al’s research into the SCN?

A

He bred mutant hamsters with a 20 hour sleep/wake cycle
When SCN cells from foetal tissue were transplanted into the brain of normal hamsters the cycle of the normal group defaulted to 20 hours

9
Q

Where does the SCN pass its information on the length of day and light that it receives to?

A

The pineal gland

10
Q

What does the pineal gland do in the night?

A

Increases production of melatonin (a chemical that induces sleep and is inhibited during periods of weeks or less

11
Q

What has melatonin also been suggested as?

A

A casual factor in seasonal affective disorder

12
Q

What does the word Zeitgeber mean?

A

Time giver

13
Q

What are exogenous zeitgebers?

A

External factors in the environment that reset our body clock through a process known as entrainment

14
Q

What happens to the biological clock in the absence of external queues?

A

It continues to take in a distinct cyclical pattern and therefore sleeping and wakefulness would seem to be determined by the interaction between internal and external forces

15
Q

What is the role of light?

A

It is a key zeitgeber and can set the body’s main pacemaker so the SCN therefore plays a key role in the maintenance of the sleep/wake cycle

16
Q

What did Campbell and Murphy suggest about light?

A

That it may be detected by skin receptor sites in the body even when the same information is not sought by the eyes. 15 participants woke up when a bright light was shone on the back of their knees - a deviation in the usual sleep wake cycle happened, sometimes up th 3 hours
Suggesting light is a powerful zeitgeber

17
Q

What is an example of social cues affecting the cycle?

A

Babies started to develop circadian rhythms at 6 weeks and by 16 weeks most babies are entrained - this is likely to be influenced by the schedules imposed by parents
When travelling to other time zones by keeping to meal and bed times you can beat jet lag