Biopsychology(endogenous pacemakers and exogenous zeitgebers)

Question 1

‘endogenous’ meaning?

Answer 1

The origins of what belong to the organism, inherited genetic mechanisms.

Question 2

Endogenous pacemakers - simple definition

Answer 2

Mechanisms within the body that regulate biological bodily rhythms.

Question 3

Exogenous zeitgebers - simple definition

Answer 3

An environment cue, such as light. This helps regulate the biological clock organism

Question 4

The suprachiasmatic nucleus as the main the endogenous pacemaker

Answer 4

The SCN
- Tiny cluster of nerve cells
- Which lies in the hypothalamus
- Plays an important role of generating the body’s circadian rhythm
- Acts as a master clock controlling sleep and arousal.
- Sends signals throughout the body in response to light or dark.
The SCN receives information about light levels due to the optic nerve
- Happens when eyes are shut, as light penetrates the eyelids. This may depend on our biological clock running slow.
- The SCN also directs signals to the pineal gland regulating the amount of melatonin (hormone) produced.

Question 5

Pineal gland -

Answer 5

More hormone melatonin at night and less melatonin and is decreased during more light levels. The SCN and pineal gland function as endogenous pacemakers in the brain. Due to their sensitivity of the light their activity must be synchronised with the light-dark rhythm of the outside world.

Question 6

‘Exogenous’ meaning

Answer 6

Anything outside the organism, Zeitgeber means the word time giver from German.

Question 7

Light as an exogenous zeitgeber -

Answer 7

• Receptors in the SCN are sensitive to changes in light levels during the day and use information to synchronise with activity of the body’s organs and glands. Light resets the internal body clock. Keeping it on a 24 hour cycle. Third type of light detecting cell called the retina, that gauges overall brightness to the internal working body clock. A protein called melanopsin is sensitive to natural light, these small retinal cells contain melanopsin and carry signals to the SCN and daily body cycle.

Question 8

Social cues -

Answer 8

• Refer to mealtimes and social events.
• Aschoff showed individuals are able to compensate for the absence of some zeitgebers like natural light. As they respond to social zeitgebers instead. It has been found that air travellers adjusted more quickly if they went outside more at their destination, This was due to them being exposed to new social cues at different time zones acting as a zeitgeber.