399891
Description
Mind Map by soozi fullstop, updated more than 1 year ago
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Created by soozi fullstop
about 11 years ago
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Exogenous Zeitgebers
- Light
- The dominant
zeitgeber in
humans
- Light can reset
the body's main
pacemaker, the
SCN.
- It can also reset
the other
oscillators located
throughout the
body.
- This is because the
protein, CRY,
(cryptochrome)
which is part of the
protein cycle, is light
sensitive.
- This is because the
protein, CRY,
(cryptochrome)
which is part of the
protein cycle, is light
sensitive.
- Campbell and Murphy (1998)
found that if you shine light on the
backs of participants' knees, their
circadian cycles could be shifted.
- The dominant
zeitgeber in
humans
- Social Cues
- Until fairly recently,
biologists thought
that social cues
were the main
zeitgeber for human
circadian rhythms.
- We eat meals at socially
determined mealtimes, go to
bed and wake up at times
designated as appropriate
for our age etc.
- Our daily rhythms
appeared to be entrained
by social convention, not
internal biology.
- Our daily rhythms
appeared to be entrained
by social convention, not
internal biology.
- Today, we know that light is the dominant
zeitgeber but in fact it is also oscillating
rhythms and some of these are not
primarily reset by light.
- For example, the
zeitgeber for cells in the
liver and heart is likely to
be mealtimes be/c these
cells are reset by eating
(Davidson 2006)
- For example, the
zeitgeber for cells in the
liver and heart is likely to
be mealtimes be/c these
cells are reset by eating
(Davidson 2006)
- Until fairly recently,
biologists thought
that social cues
were the main
zeitgeber for human
circadian rhythms.
- Temperature
- Biological rhythms
can also be controlled
by temperature.
- e.g. Leaves on
deciduous trees change
colour and fall of because
of changes in
temperature as well as
daylight.
- e.g. Leaves on
deciduous trees change
colour and fall of because
of changes in
temperature as well as
daylight.
- Temperature is also a
factor in the onset of
hibernation.
- In the absence of light, temperature
may be the dominant zeitgeber.
(Lopez-Olmmeda et al, 2006)
- Biological rhythms
can also be controlled
by temperature.
- An Endogenous Zeitgeber is an
environmental cue that can affect
and even reset our internal
biological clocks. For example,
daylight. The process of resetting
the biological clock with
exogenous zeitgebers is known
as entrainment. Opposite is the
'free running' - absence of
zeitgeber cues.
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