Endogenous Pacemakers and Exogenous Zeitgebers

Question 1

Whta is an endogenous pacemaker

Answer 1

internal body clocks that regulate many of our bio rhythsm such as influence of scn on the swc

Question 2

what is an exogenous zeitgeber

Answer 2

external factors that affcet or entrain our biological rhythsm such as the infleunce of light on the swc

Question 3

tell me 3 important thing about suprachiasmatic nucleus

Answer 3

tiny bundle of nerve cells located in the hypothalamus in each hemisphere of the brain

priamry endogenous pacemaker in mammalian species

influential in maintaing circadian rhtytms e.g swc

Question 4

nerve fibres that are connected to the eye cross where

Answer 4

optic chiasm on theri way to the left and right visual area of the cerebral cortex

Question 5

where does the scn lie

Answer 5

just above the optic chiasm

Question 6

how to remebr where scn lies

Answer 6

supra menas above

Question 7

what does the scn recieve

Answer 7

info about light directly from this structure (lieing above optic chaism?)

continues even when our eyes are closed

Question 8

the scn recieve info about light whihc ocntinues when our eyes are closed what does this enable

Answer 8

the biological clock to adjust to chanign aptterns of dayligth while we are asleep

Question 9

animal studies and the scn

Question 10

how has the influence of the scn been demonstrated

Answer 10

animal studies

Question 11

who are the researchers that did animal studies to see infleunce on scn

Answer 11

decoursey et al

ralph et al

Question 12

explain decoursey et al studie

Answer 12

destroyed scn connections in brian of 30 chipmunks

then returned to their natural habittat

observed for 80 days

SWC of chipmunks disapeared and by end of study a significant proportion of them had been killed (presumably cause they were awake , active and vulnerable to attack when they should’ve been asleep)

Question 13

explain ralph et ak study

Answer 13

bred mutant hamsters with a 20 hour swc

when scn cells from foetal tissue of mutant hamsters were transplanted into the brains of normal hamsters the cycles of the 2nd group defualted to 20 horus

Question 14

pineal gland and melatonin

Question 15

the scn passes on wat type of info to where

Answer 15

scn passes info on day length and light taht it recieves to the pineal gland

Question 16

what is the pineal gland

Answer 16

another endogenous mechanism guifing the swc

Question 17

during the night what does the pineal gland do

Answer 17

increases production of melatonin

Question 18

melatonin is a chemical that

Answer 18

induces sleep

inhibtied during periods of wakefulness

its also been suggested as a causal factor in SAD

Question 19

what does zeitgeber mean

Answer 19

time giver

Question 20

exogenous zeitgebers are external factors that reset our biological clocks thorugh a process known as

Answer 20

entrainment

Question 21

in the abscence of external cues what happens

Answer 21

free runing bio clock that contorls swc continues to tick in a distinct cyclical pattern

its then brought in line by environemtnal cues so there is an interaction of internal external factors

Question 22

what are the 2 main exogenous zeitgebers

Answer 22

light

social cues

Question 23

light is a key zeitgeber in

Answer 23

humans

Question 24

how do we know light plays a role in teh maintenance of sws

Answer 24

it can reset the bodys main endogenous pacemaker, the scn

Question 25

light has what type of influence on key processe in the body

Answer 25

indirect influence

Question 26

light has an indirect influecne on key processes in the body that control funcitnos such as

Answer 26

hormone secretion

blood circulation

Question 27

in an inovaitve study waht did x x resercherd demonstrate

Answer 27

campbell and murphy

demonstrated lgith may be detected by skin receptor sites on teh body even when same info is not recieved by eyes

Question 28

putline campell and murphy study into light being detected by skinr eceptors sites on body even when same info not recieved by eyes

Answer 28

15 pt woken at various times
light pad shone on back of their knees

researchers managed to produce a deviationin the pt usual swc of up to 3 hours in some cases !

Question 29

what did campbell and murphys study suggest

Answer 29

light is a powerful expgenous zeitgeber that doesnt necessarily rely on the eyes to exert its influecne on the brain

Question 30

a new born banies intial sleep cyle is pretty much

Answer 30

random

Question 31

at about 6 weeks of age for a baby what happens

Answer 31

circadian rhythms begin

Question 32

by 16 weeks babies rhythsm have been

Answer 32

entrained by schedules imposed by parents including adult determiend mela and bed timees

Question 33

what does reearc on jet lag suggest

Answer 33

adapting to lcoal times for eating and sleeping rather than respoding to ones own feling of hunger and fatigue

is an effective way of entrinng circadian rhythms and beating jet lag when travelling long distances

Question 34

eval 1 - reearch support endogenous pacemakers

research support for the importance of endogenous x in particular xxx

x bred hamsters so they had circ rhtyms of x instead of 24 horus
scn neurons from x hamsters were x into the x of x hamsters who subsequently displayed the same x circadian rhythm of xx hours
showing transplanted scn had x its pattern on x

however this research is x to x becuse uses x
humans would repsond v x to manipulations of bio x , not just cuase we diff x but also vast differnces between x x

so while research demostrates x of scn and how endogenous pacemkaers impact bio rhtytnms( e.g xxx ) research carried out on x may be unable to explain role of endogenous pacemkaers on SWC in x

Answer 34

research support for importance of endogenous pacemkaerd in particular scn

morgan bred hamsters so they had circ rhtyms of 20 instead of 24 horus
scn neurons from abnormal hamsters were transplanted into the brians of normal hamsters hwo subsequently displayed the same abnormla circadian rhythm of 20 hours
showing tranplanted scn had imposed its pattern on hamsters

however this research is difficult to generalise becuse uses hamsters
humans would repsond v differntly to manipulations of bio rhythms , not just cuase we diff biologically but also vast differnces between environmentla contexts

so while research demostrates significance of scn and how endogenous pacemkaers impact bio rhtytnms( e.g swc ) research carried out on animals may be unable to explain role of endogenous pacemkaers on SWC in humans

Question 35

eval 2 - research support exogenous pacemakers

research suport for exogenous zeitgebers on the swc

when siffre returned from x stay w no x or x he believed the x to be a month x than it was , demonstrating hte x of the exogenous x (light) on the xxx

hoever siffre case study been subject to x , as he was the x and sole x in his case study , ther are x issues with potential x x and a lack of x to a wider x

so while results suggest the xx hour swc was increased by the x of x zeitgberes, the finidngs should be treated with x; we are uanble to x whether the role of exogenous zeitgebers effects the xxx ina x population on the basis of this case study x

Answer 35

research suport for exogenous zeitgebers on the swc

when siffre returned from underground stay w no clocsk or light he believed the dat eto eb a month earleir than it was , demonstrating hte importance of the exogenous zeitgber (light) on the swc

hoever siffre case study been subject to crtiticsim , as the researcher and sole pt in his case study , ther are sever issues with potential researcher bias and a lack of generalisabilty to a wider population

so while results suggest the 24 hour swc was increased by the lack of exogenous zeitgberes, the finidngs should be treated with caution; we are uanble to conclude whether the role of exogenous zeitgebers effects the swc ina wider population on the basis of this case study alone

Question 36

eval 3 research suport is reductionsit

despite research support for role of endogenous pace,akers and exogenous zeitgbers , the argument can still be considered to be x for x the copmlex x x

e.g it culd be argued teh swc is influenced by x x and x norms i.e sleep occurs when its x becuase that is teh x x and it wouldnt be socially x for a perosn to conduct their x x at x

so research dicuseed here could be x for being x as it only considers a x range of factors e.g x and x and fails to x the other x suggesting our x of the effect of endogenous pacemkaers and exogenous zeitgberes on the swc is x

Answer 36

despite research support for role of endogenous pace,akers and exogenous zeitgbers , the argument can still be considered to be reductionsit for oversimpligiifn the copmlex human phenomena

e.g it culd be argued teh swc is influenced by pther poepl and social norms i.e sleep occurs when its dark becuase that is teh socialnorms and it wouldnt be socially accpetbale for a perosn to conduct their daily routines at night

so research dicuseed here could be criticised for being reductionsit as it only considers a ltd range of factors e.g scn and ligth and fials to cosider the other vieewpoitns suggesting our understanding of the effect of endogenous pacemkaers and exogenous zeitgberes on the swc is limited