The Role of Endogenous
and Exogenous Factors in
Bodily Rhythms
Descrição
A Level PY4 Psychology (Levels of Consciousness) Mapa Mental sobre The Role of Endogenous
and Exogenous Factors in
Bodily Rhythms, criado por HeyThereIAmKyle em 05-06-2013.
The Role of Endogenous
and Exogenous Factors in
Bodily Rhythms
Biologicial Rhythms: regular
variations in the biological
activity of living organisms,
such as sleep, body
temperature
Ultradian: a biological
cycle that lasts less than
24 hours (REM Sleep)
Circadian: A biological
rhythm that lasts 24
hours (sleep-wake cycle)
Edogenous Pacemakers
Anotações:
Biological 'clocks' in the brain are controlling biological rhythms
DeCoursey: Removed the SCN
in 30 chipmunks and then put
back in their natural habitat. After
80 days those who had their SCN
removed were more likely to die
Suprachiasmatic Nucleus in the
hypothalamus is responsible for
controlling bodily rhythm
Morgan: bred mutant hamsters
and gave them Circadian Rhythms
of 20 hours then transplanted the
SCN into normal hamsters. The
normal hamsters displayed
Circadian rhythms
Aschoff and Weaver: placed
P's in a WWII bunker and
denied them social or
environmental cues. Most
showed CR of 24 hours.
Exogenous factors
must help in CR as
the P's lost a few
minutes in their CR
every day
The SCN sends signal to the pineal gland,
which produces melatonin. Melatonin
induces sleep and it is underneath the top of
the skull so that light induces sleep.
Light as the
exogenous
factor plays a
role
Folkard: Kate Aldcroft spent
time in a cave. Her temperature
was on a 24 hour CR but her
sleep on a 30
Kleitman: P's lived in a
bunker, with no light or
dark cues.The CR were
25-27 hours
Lacks generalisability. Also,
Siffre maintained a normal CR
which shows that exogenous
factors also play a part
Miles: Man was blind from birth
but still had a CR of 24.9 hours.
Even though social cues were
experienced to him his internal
pace did not slow down
suggesting that CRs are biological
Exogenous Zeitgebers
Anotações:
External Stimuli that help towards regulating biological rhythms to the outside world
Can be in the form of
objects (clocks) or
natural occurences
(light levels)
Michael Siffre went to live in
a cave for 6 months. When
he was awake the lights were
on, and vice versa. His CR
was 25-30 suggesting
exogenous factors affect
bodily rhythms
Cszeliar: Artificial light does not effect
the CR. 24 m/f lived for a month in
subdued light, and tried to place them
in an artificial CR. Their CR was still 24
To suggest we
have a 25hr CR is
an evolutionary
disadvantage as
animals survive
with a 24hr CR
Reductionist - CRs are also
controlled by ednogenous,
not just exogenous
Davison: Social cues
- We follow social
cues as we grow up.
For example, our liver
might rest when it's
meal time
Campbell and Murphy: Shining
the light on the back of a P's
knees shifted their CRs
showing that exogenous
factors affect bodily rhythms
Seasonal
Defective Order:
Individuals feel
more depressed
in the winter and
elated in the
summer
Rosenzweig: Depression
is mostly found in Northern
and southern countries
because they have less
light.
Stevens:
Artificial
light can
change
CRs
The two systems actually work together.
The Biological side needs to run because
of our metabolism, and other bodily
functions. The environmental aspect is
there to coordinate the physical
processes in our body. The exogenous
zeitgeibers also tune social cues in order
to fluctuate with daily rhythms. Day and
night, shorter days in the summer