endogenous pacemakers and exogenous zeigebers Flashcards
where is the SCN located
in the hypothalamus in both hemispheres
is the SCN an endogenous pacemaker or exogenous zeitgeber
endogenous pacemaker
what is the role of the SCN
to maintain circadian rhythms
what does the SCN do in terms of light
it receives information about light from the optic chiasm (which is where nerve fibres that are connected to the eye cross over on their way to the left and right visual areas of the cerebral cortex) which lets the biological clock adjust to changing patterns of daylight when we are asleep
explain the procedure of Decoursey’s study (2000)
destroyed the SCN connections in the brain of 30 chipmunks who were then returned to their natural habitat and observed for 80 days
what were the findings of Decoursey’s study
their sleep/wake cycle disappeared by the end of the study and most were killed by predators
what were the findings of Decoursey’s study
their sleep/wake cycle disappeared by the end of the study and most were killed by predators
explain the procedure of Ralph’s study in 1990
bred mutant hamsters with a 20 hour sleep/wake cycle
what were the findings of Ralph’s study
when SCN cells from the foetal tissue of the mutant hamsters was transplanted into the brain of the normal hamsters, the cycles of the normal masters went to 20 hours too
what is the sleep wake cycle controlled by
endogenous pacemakers
what is melatonin’s role in sleep
melatonin induces sleep
give 2 examples of an exogenous zeigeber
light
meal times
what are exogenous zeigebers
external cues which entrain (reset) our biological clocks
what are the 2 roles of light
- can reset the SCN
- controls hormone secretion and circulation
explain the procedure of Campbell and murphy’s study in 1998
15 participants were woken at various times and a light was shone on the backs of their knees
