Endogenous And Exogenous Zeitgebers

Question 1

What are endogenous pacemakers

Answer 1

They regulate biological rhythms and they are the body’s internal biological clock

Question 2

What are exogenous zeitgebers

Answer 2

External cues including light that help regulate the internal biological clocks

Question 3

Describe the endogenous pacemaker suprachiasmatic nucleus ( SCN)

Answer 3

It is linked to the pineal gland which both maintain the sleep wake cycle
- SCN (master clock) located in the hypothalamus
-SCN receives info about light levels from the optic nerve which sets the circadian rhythm so its synchronised with outside world
-SCN sends signals to pineal gland which increase production of melatonin at night to help induce sleep

Question 4

Describe how light is an exogenous zeitgebers

Answer 4

They re external cues responsible for resetting biological clocks
- light is responsible for resetting the body clock each day keeping a 24 hr cycle
-SCN contains receptors sensitive to light which synchronise internal organs and glands
- melanopsin is a protein in the eye which is sensitive to light and carries signals to SCN to set the 24 hr body cycle

Question 5

AO3

Answer 5

+research support by Morgan showing the importance of SCN
- bred hamsters to have a 20 hr cycle not 24- the SCN neurons then transplanted to normal hamsters from these bred hamsters- now they have an abnormal circadian rhythm of 20hr
— this research uses hamsters
- human responds differently to changes if their biological rhythm- biological and environmental differences human have
+ research to support role of melanospin
- majority of blind people who have some light perception have normal circadian rhythms but those with no light perception have abnormal circadian rhythm- importance of melanospin
+ research support by siffre
- cave- no clocks or light- he believed it was a month earlier then it was- 24 hr sleep cycle increased due to lack of external cues