Endogenous Pacemakers

Question 1

what is an endogenous pacemaker?

Answer 1

internal mechanisms that govern biological rhythms

Question 2

what is the suprachiasmatic nucleus?

Answer 2

tiny bundle of nerve cells in the hypothalamus which helps maintain circadian rhythms

the SCN lies just above the optic chiasm and recieves information about light delivery from when nerve fibres cross at the optic chiasm on their way to the visual cortex

continues when our eyes are closed

Question 3

what did DeCoursey et al (2000) do?

Answer 3

destroyed the SCN connections in the brains of 30 chipmunks who were returned to their natural habitat and observed for 80 days

Question 4

what did DeCoursey et al (2000)’s study find?

Answer 4

the chipmunks’ sleep/wake cycle disappeared and may were killed by predators

Question 5

what was Ralph et al (1990)’s study?

Answer 5

bred ‘mutant hamsters’ with a 20-hour sleep/wake cycle

SCN cells were transplanted from the foetal tissue of these hamsters into the brains of normal hamster, which then developed 20 hour cycles

Question 6

what is the role of the pineal gland and melatonin and the SCN?

Answer 6

the SCN passes information on day-length to the pineal gland, which increases melatonin production during the night

melatonin linked to SAD

Question 7

what are weaknesses of research into endogenous pacemakers?

Answer 7

SCN may obscure other body clocks - Damiola et al (2000) changed feeding patterns of mice which altered circadian rhythms

can’t generalise from animals