endogenous pacemakers and exogenous zeitgebers

Question 1

what’re endogenous pacemakers

Answer 1

internal body clicks that regulate our biological rhythms

Question 2

what’re exogenous zeitgebers

Answer 2

external factors that effect out biological rhythms

Question 3

What is the SCN

Answer 3

•The Suprachiasmatic nucleus
•tiny bundle of nerve cells in the hypothalamus in each hemisphere
•maintains sleep cycle, optic nerve fibres provide info about light outside, influencing the melatonin levels.
•can happen with eyes open or closed

Question 4

how does the scn relate to the pineal gland

Answer 4

passes info on light to the pineal gland. at night the pineal gland produces melatonin

Question 5

what’s the case of DeCoursey’s chipmunks

Answer 5

removed SCN from 30 chipmunks then returned to wild for 80 days and observed. sleep/wake cycle disappeared with many dying/disappearing (awake when they shouldn’t etc)

Question 6

what’s the case of Ralph’s hamsters

Answer 6

bred 20 hour sleep cycle ‘mutant’ hamsters, their SCN cells then replaced those of normal hamsters, defaulting from 24h to 20h of sleep

Question 7

how is light an EZ

Answer 7

can reset the main endogenous pacemakers of the SCN, with indirect influences on other hormone secretion and blood circulation

Question 8

what was Campbell & Murphy’s research on light as an EZ

Answer 8

wanted to investigate skin receptor sites.
15 participants woken at various times and light pad shone to the back of the knee
managed to produce up to 3h of sleep cycle deviation
light is still a crucial EZ when not detected by the eye