Endogenous pacemakers and exogenous zeitgebers Flashcards
endogenous pacemakers are
internal parts that control rhythmic phisiological activity
main endogenous pacemaker
SCN that is placed within Hypothalamus
example of how the endogenous pacemaker work
light-retina-melanopsin-hypothlamus-SCN-pineal gland-production of melatonin-sleepiness
SCN then receives feedback on sleep urge
what are the exogenous zeitgebers
exyternal cues that trigger endogenous pacemakers and regulate them
what are the main exogenous zeitgebers
light and social cues
more info about SCN
how it adjusts
SCN receives info about light via Optic nerve
happens when eyes are shut
light automatically ajusts the clock, putting its rhythm with the world outside.
role of melanopsin
it is sensetive to natural light
small number of retinal cells contain melanopsin
they carry signals to SCN to set the daily body cycle
Endogenous pacemakers and exogenous zeitgebers
eval 1 top
an animal study was carried out by Morgan to support importance of SCN
Endogenous pacemakers and exogenous zeitgebers
eval 1 point
1 group of hamsters had an abnormal circadian rhythm of 20h insted of 24h.
SCN neurons of this hamsters were transplanted into the normal hamsters.
these normal hamsters later showed a chift in the circadian rhythm from 24 to 20h
Morgan then did the same but the other way round
Endogenous pacemakers and exogenous zeitgebers
eval 1 tail
shows the imoprtance of scn in process of setting circadian cycle, and emphasises that it is the most important endogenous pacemaker that can influence circadian rhythm
Endogenous pacemakers and exogenous zeitgebers
eval 2 top
exposure to the artificial light at night disrupts circadian cycle and has poor affects on health
Endogenous pacemakers and exogenous zeitgebers
eval 2 point
Touitou’s reserch shows that teens spend a huge amount of time on elctronic devices att night.
the LED bulbs of these devices have blue light, which is very active on the circadian clock
that leads to the supression of secretion of melotonin and therefore results in disruption of circadian clock
Endogenous pacemakers and exogenous zeitgebers
eval 2 tail
sleep and light
in a long run it leads irregular sleep, it becomes shortened and delayed.
combination of sleep deprivation and sleep disruption results in higher risk of cardiovescular disorder, depression
Endogenous pacemakers and exogenous zeitgebers
eval 3 top
support for the role of melanopsis is demonstrated by the study of Blind people
Endogenous pacemakers and exogenous zeitgebers
eval 2 double
ecological validity of these findings is high, as it leads to knowing the sleep paterns and therefore people are able to prevent such disorders form happening if they are conscious.
this would mean the nation can become more healthy and therefore productive which is always good for the economy
Endogenous pacemakers and exogenous zeitgebers
eval 3 point
some blind people are still able to have a normall 24h circadian rhythm in response to light, even if they lack actual perception of light
skene and arendt in their study show that the majority of blind people with some perception have a perfectly working rhythm
one more time supporting the fact that exogenous zeitgebers have an important role
Endogenous pacemakers and exogenous zeitgebers
eval 3 tail
pathway form retina to SCN that has melanopsin cells is very imoprtant.
it sets the biological clock and helps to regulate endogenus pacemakers
this means that blind people with absolutely no perception have abnormal circadian rhythm
Endogenous pacemakers and exogenous zeitgebers
eval 4 top
Vetter shows the importance of light as an exogenous zeitgeber in the setting of circadian rhythm
Endogenous pacemakers and exogenous zeitgebers
eval 4 point
one group - ‘warm’ artifical light
second group - ‘blue-enriched’ light
5 weeks
ppts kept a daily sleep log + devices that measure movement
over the course of study sunrise advanced by 42 min
Found: group1 sycnhronised their rhythm with natural light of the dawn
group2 - didnt show they same adjustment, insted sybchronised with the office hours
Endogenous pacemakers and exogenous zeitgebers
eval 4 tail
the results show that light is the main EZ that can influence SCN
and its effectivenes depends on its spectral composition
