What is an Endogenous Pacemaker?

Internal body clock

What is an Exogenous Zeitgeber?

External cues from the Environment

What does SCN stand for and define it?

(3 points)

Suprachiasmatic Nucleus is a cluster of nerve cells. Obtains information about light from the eye, even when it is closed, as light still passes through the eye lids.

If our internal clock is running slow then the morning light automatically shifts it ahead. 

What are the 2 parts of the SCN?

In one hemisphere of the Brain is the Ventral SCN (easily reset by external cues) and in the other hemisphere is the Dorsal SCN (not easily reset).

Describe the system through which melatonin is produced?

(SCN -> PG -> M)

The SCN sends signals to the pineal gland which increases melatonin production at night. Melatonin induces sleep by inhibiting brain mechanisms which promote wakefulness.

Name a Psychologist supporting Endogenous Pacemakers?

(Initials: M)

Morgan.

Why does Morgan support Endogenous Pacemakers?

Bred mutant hamsters so they had a 20 hour circadian rhythm. He then transplanted their mutated SCN's into normal hamsters and found that the normal hamsters adopted the new rhythms.

What is Entrainment?

Process of resetting the internal clock through external cues (exogenous zeitgebers).

What are the 3 main Exogenous Zeitgebers?

Light

Social Cues

Temperature

Outline Light as an Exogenous Zeitgeber?

Can reset the SCN as well as other oscillators throughout the body because the proteins they are made of, are light sensitive.

Name a Psychologist who investigated Light as an

Exogenous Zeitgeber?

(Initials: C&M)

Campbell & Murphy

How did Campbell & Murphy investigate Light as an

Exogenous Zeitgeber?

Found that if you shine light on the back of participants' knees, this can shift their circadian rhythms.

Name a Psychologist who investigated Social Cues?

(Initials: D)

Davidson

How did Davidson investigate Social Cues as an

Exogenous Zeitgeber?

Found that the zeitgeber for the heart and liver was most likely to be mealtimes as these cells are reset by eating.

Describe Temperature as an 

Exogenous Zeitgeber?

In cold-blooded animals, cold temperature signals a time for reduced activity and warm temperature signals a time for activity.

Name a Psychologist who investigated Temperature as an

Exogenous Zeitgeber?

(Initials: B)

Buhr et al.

How did Buhr et al. investigate Temperature as an

Exogenous Zeitgeber?

Found that daily changes in body temperature are governed by their own clock and can reset other rhythms.

Name 2 Psychologists who support

Exogenous Zeitgebers?

(Initials: B, S)

Boivin et al.

Stevens

Why does Boivin et al. support

Exogenous Zeitgebers?

Found that circadian rhythms can be altered by even dim lighting, although brighter lighting is more effective.

Why does Stevens support

Exogenous Zeitgebers?

Suggested that exposure to artificial lighting can be harmful as it disrupts rhythms and therefore disrupts melatonin production which can have negative effects. May explain why some women in industrialised societies are more likely to develop breast cancer.

What is one IDA criticism for both 

Endogenous pacemakers and Exogenous zeitgebers?

(NH)

A lot of research into both areas, involve non-human (animal) studies which raises ethical issues of harm to the animals as well as generalisability to humans.