Bio Rhythms - Circadian Rhythm Flashcards
all livng organisms are subject to
biological rhthms
biological rhythms extert an important influence on
the way in whih body systems behave
biological rhythms are governed by
endogenous pacemakers
exogenous zeitgebers
what are endogenous pacemakers
body’s internal biological clocks
what are exogenous zeitgebers
external changes in the environment
what ar eultradian rhythms
rhythmas that occur multiple times in teh day
What are infradian rhythms
rhythms that take longer than a day to complete
circadian rhythm is
rhythms that last around 24hours
2 exmaples of circadian rhythm
sleep wake cycle
body temp
the fact we feek driwsy in night time and alert in day shows the effect of
daylight
daylight is an
importnat exogenous zeitgeber on our sleep wake cycle
sleep wake cycle is also governed by an
enodgenous pacemaker
the endogenous pacemkaer that governs the the sleep wake cycle is called the
suprachiasmatic nucleus (SCN)
QWhere does the SCN lie
just above optic chiasm
the optic chiasm provides info from ..
the eye about light
what can reset teh SCN
exogenous zeitgeber
give good q about bio clock
what if left to its own devices without influence of external stimuli such a slight
Describe Siffre
self styled caveman that spent several extendedn periods underground to study effects on his own bio rhythms
what was the conditions in the cave
deprived of xp to natural light and sound
but accessto adequate food and drink
Descrbe in detail wen labri siffre emetrged from cave
mid sept 1962
after two months in cave of southern alps
beleived it to be mid august
what did siffre do a decade later
peformed smilar event but for 6 months in a Texan Cave
what happened in each of Siffres cave xp
his free running bio rhythm settled down to one
just beyond usual 24 hour (around 25)
though he did continue to fall asleep + wake up on reg schedule
OTHER STUDY - Similar results of cave study recorded by
aschoff and Wever 1976
What did aschoff and wever do
convinced group of pt to spend 4 weeks in WW2 bunker deprived of natural light
what were reuslt of aschoff and wever study
all but one pt (whose SWC extended to 29hours) displayed circ rhythms between 24-25 hours
Whta do both siffre xp and bunker study suggest
natural SWC may be slihtly longer than 24hrs but
entrained by exog zeitgebers associated with our 24hr day ( e.g # of daylight hours, typical mealtimes
despite results of iffre xp and bunker study we shuildnt
overestimate influence of exog zeitgebers on our internal bio closk
what study shws us we huldnt over estimate influence of exo zeit on our interna bio clock
Folkard et al studied group 12 people afgreed live in dark cabe 3 weeks
retired to bed when clock 11:45p,
rise when said 7:45 am
what ahppened voer course of folkard study
researchers gradually sped up clock (pt didnt know)
ao 24hr day eventlasted 22 hours
in folkard cve study only on ept
able to comfortably adjust to new routine
what does folkard study suggest
exsitence of strong free-runnig circ rhythm that cant easily be overriden by exog zeitgebers
STRENGTH - REAL LIFE APPLICATION IN CHRONOTHERAPEUTICS - Point
real world application of circ rhtym research is it has led to improvements in medical x - x - study of how timing affects drug treatments
x time pt take medi is very x as can have a x impact on treatmtent x
x right x of drug released in x area of body at x drug is most x
e.g risk of heart x greatest during x x hours after x up
therefore x medications have been developed with a x drug x x
these meds can be admin before person foes to sleep at xpm, but x drug not released till x period of x am to x (Evans and marain 1996)
shows research into circ rhytms not just x our x of human x
but research x have led to x of treatment for x wih x of conditions requiring drug x
real world application of circ rhtym research is it has led to improvements in medical treatments - chronotherautics - study of how timing affects drug treatments
circ rhths co ord some body basic processes e.g HR , digestion -
specific time pt take medi is very imp as can have a sig impact on treatmtent success
essential right cnoc of drug released in target area of body at time drug is most needed
e.g risk of heart attacks greatest during early morning hours after waking up
therefore chronotheraputic medications have been developed with a novel drug delivery system
these meds can be admin before person foes to sleep at 10pm, but actual drug not released till vuln period of 6 am to noon (Evans and marain 1996)
shows research into circ rhytms not just furthered our understandnig of human body
but research appl have led to imporvement of treatment for pt wih varity of conditions requiring drug therapy
LIMITATION - Case study and small sample - POINT
LIMIT OF RESEARCH INTO swc is tendency to involve small groups of pt or sing indi e.g siffre
People may not be reresentative of wider pop therfore limitinf extent to which meaningful genralisation can be amd e
in latest cave xp siffre observed at age of 60 - his internal body clock ticked much more slowly than wehen he was a young man
Illustrates fcat even when same person involved , there are factors that vary that can prevent genral conc beng drawn
strenght - shift work
provides an understanding of the x consequences that occur when they’re CR X (X)
e.g. night workers engaged in x work experience a period of reduced x around 6 in the morning (a circadian trough) meaning x and x are more likely
research has also pointed to a x between shift work and x x - shift workers are x* more likely to develop x x than people who work more x work patterns (Knutsson)
shows that research into the sleep/wake cycle may have real-world x implications in terms of how best to manage worker x
provides an understanding of the negative consequences that occur when they’re disrupted (desynchronisation)
e.g. night workers engaged in shift work experience a period of reduced concentration around 6 in the morning (a circadian trough) meaning mistakes and accidents are more likely (Boivin)
research has also pointed to a relationship between shift work and poor health - shift workers are x3 more likely to develop heart disease than people who work more typical work patterns (Knutsson)
shows that research into the sleep/wake cycle may have real-world economic implications in terms of how best to manage worker productivity
counterpoitn studies investigating shift work use correlational methods
studies investigating effects of shift works tend to use x methods
so x to establish wehther x of swc is actually c casue of x effects
there may be other factors e.g high x rates in shift workers may be due to strain of x sleep and other x such as missing x x events
this suggest x factors may not create x x associated with shift x
studies investigating effects of shift works tend to use correlational methods
so difficult to establish wehther desynchronisation of swc is actually c casue of -ve effects
there may be other factors e.g high divorce rates in shift workeres may be due to strain of deprived sleep and other influences such as missing imp family events
this suggest bio factors may not create adverse consequences associated with shift work
