Endogenous pacemakers and exogenous zeitgebers

Question 1

endogenous pacemakers are

Answer 1

internal parts that control rhythmic phisiological activity

Question 2

main endogenous pacemaker

Answer 2

SCN that is placed within Hypothalamus

Question 3

example of how the endogenous pacemaker work

Answer 3

light-retina-melanopsin-hypothlamus-SCN-pineal gland-production of melatonin-sleepiness

SCN then receives feedback on sleep urge

Question 4

what are the exogenous zeitgebers

Answer 4

exyternal cues that trigger endogenous pacemakers and regulate them

Question 5

what are the main exogenous zeitgebers

Answer 5

light and social cues

Question 6

more info about SCN

how it adjusts

Answer 6

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.

Question 7

role of melanopsin

Answer 7

it is sensetive to natural light
small number of retinal cells contain melanopsin
they carry signals to SCN to set the daily body cycle

Question 8

Endogenous pacemakers and exogenous zeitgebers

eval 1 top

Answer 8

an animal study was carried out by Morgan to support importance of SCN

Question 9

Endogenous pacemakers and exogenous zeitgebers

eval 1 point

Answer 9

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

Question 10

Endogenous pacemakers and exogenous zeitgebers

eval 1 tail

Answer 10

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

Question 11

Endogenous pacemakers and exogenous zeitgebers

eval 2 top

Answer 11

exposure to the artificial light at night disrupts circadian cycle and has poor affects on health

Question 12

Endogenous pacemakers and exogenous zeitgebers

eval 2 point

Answer 12

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

Question 13

Endogenous pacemakers and exogenous zeitgebers

eval 2 tail

sleep and light

Answer 13

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

Question 14

Endogenous pacemakers and exogenous zeitgebers

eval 3 top

Answer 14

support for the role of melanopsis is demonstrated by the study of Blind people

Question 15

Endogenous pacemakers and exogenous zeitgebers

eval 2 double

Answer 15

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

Question 16

Endogenous pacemakers and exogenous zeitgebers

eval 3 point

Answer 16

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

Question 17

Endogenous pacemakers and exogenous zeitgebers

eval 3 tail

Answer 17

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

Question 18

Endogenous pacemakers and exogenous zeitgebers

eval 4 top

Answer 18

Vetter shows the importance of light as an exogenous zeitgeber in the setting of circadian rhythm

Question 19

Endogenous pacemakers and exogenous zeitgebers

eval 4 point

Answer 19

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

Question 20

Endogenous pacemakers and exogenous zeitgebers

eval 4 tail

Answer 20

the results show that light is the main EZ that can influence SCN
and its effectivenes depends on its spectral composition