Endogenous Pacemakers^

Question 1

The Suprachiasmatic Nucleus. Where + What?

Answer 1

tiny bundles of nerves in hypothalamus in both hemispheres

Question 2

The Suprachiasmatic Nucleus Where?

Answer 2

primary EP in mammals
- regulate many circadian rhythms
above the optic chiasm
- receive info about light from it
- even when eyes are shut (bio clock adjust)

Question 3

DeCoursey et al

Answer 3

destroyed SCN connections in 30 chipmunks
returned them to their natural habitat
observed for 80 days
End - most been killed as dont have a sleep wake cycle as SCN destroyed so can’t detect light/ dark

Question 4

Ralph et al

Answer 4

bred mutant hamsters with 20h cycle
SCN cells in foetal tissues of mutant went to normal hamsters
cycle defaulted to 20h as normals adopted the bio of mutants and adjusted their cycle

Question 5

Beyond the Master Clock

Answer 5

Peripheral oscillators in other organs
- influenced by SCN but act independently
Damjola et al
- change feeding patterns in mice
- could change circadian rhythm for up to 12h but SCN unaffected

Question 6

Interactionist System

Answer 6

EP can’t be studied in isolation
- unlikely to be without EZ
Siffre
- artificial light, bio clock influenced by light EZ
EZ and EP interact, so no sense to seperate them

Question 7

Ethics

Answer 7

animal studies
DeCoursey et al
- destroyed SNC connections in 30 chipmunks
Ralph et al
- bred mutant hamsters with a 20h cycle
Protection from harm
Lack of informed consent

Question 8

Environmental Observations

Answer 8

EZ dont have the same effect in all environments
- those who live in places with extreme light/ dark
Artic Circle have similar patterns all year despite 6 months being in complete darkness
EP have more control over bio rhythms and can overrside envi changes

Question 9

Case Study Evidence

Answer 9

Miles et al
- recount the story of a young blind mean with circadian rhythm of 24.9h
- despite exposure to social cues, his sleep cycle can’t adjust
- has to take sedatives and stimulants to keep pact with 24h
EZ not as influential bio rhythm as EP since it took a bio change for him to adjust to 24h day

Question 10

Age Related Insomnia

Answer 10

evidence of poor quality sleep when old
Duffy et al
- may be due to natural changes in circadian rhythm
- can resist in sleep earlier and a broken sleep at night
- medication to increase melatonin

Question 11

VS Age Related Insomnia

Answer 11

Hood et al
- management of insomnia improved if elderly were more active and exposed to light
Suggest EZ are more responsible for the changes in sleep patterns with age