This file accompanies a YouTube clip. It distinguishes allostasis from homeostasis and provides a brief overview of the allostatic response and allostatic load - see facebook page for link to clip - ePsychVCE.com (or website of same name)
1. Homeostasis (homeo = stable)
Key Points
• Our internal states are constantly
being disturbed & corrected
• Specifically homeostasis involves
continual regulation of vital body
functions such as body temp, oxygen
levels, blood-glucose levels, water
content, ion content, etc to a level of
balance
• So the body takes corrective action
e.g.. sweating to cool skin, shivering to
warm the body
• But the regulation of the body occurs Note: Body
by a single point e.g. via alternation of
blood oxygen levels (only) temperature
• The body can only cope with minor can only vary
variations i.e. it must operate within by 5-6%
set limits in order to survive
2. Allostasis (Allo = variable; stasis = stand)
Key Points
• Achieves physiological or
psychological stability through
behavioral or physiological change
• Thus the body can meet and copy
with internal/ external demands
• brain tells the body to maintain
physiological stability by adapting to
changes caused by stressor e.g.
increase in HR – to enable our body
to exercise (without the muscles
being deprived of level of blood
required for exertion)
• Via the allostatic systems e.g.
Autonomic.N.S, HPA axis, immune
system, cardiovascular system, etc
3. Allostasis
• Thus is a more dynamic & adaptive process (than homeostasis)
• E.g. if dehydrated, sweat levels, kidneys, mucous membrane, eyes &
nose all reduce output
• Key point: the body can cope with large changes in response to
changing conditions via both internal & external demands
• So our body can function efficiently during variable states such as
sleep/ exercise; quiet/ loud; hot/ cold; hunger/ full; isolation/
crowds; safe/ danger – via increase/ decrease in HR/ Blood
pressure/ Respiration rate/
Note: Heart rate can
increase by 250% for
an adolescent (from
a relaxed state to a
state of high
physical exertion
4. Allostatic response
Allostatic Response
• Increases arousal in response to a stress – via HPA axis &
sympathetic.N.S (thus is good in the short term)
Allostatic response involves:
Increase in Physiological arousal to deal with stressor
i.e. activation of HPA axis
When the stressor has been successfully dealt with:
The Brain switches off the allostatic response to reduce
the wear & tear on the body
5. Allostatic load
Allostatic Load (think of it as
overLOAD)
• Allostatic load refers to the Genetics
cumulative cost to the body of
allostasis
• Excessive energy consumption Context
during high stress times
• Can diminish effectiveness of
Allostatic response
• Thus potentially triggering
physiological/ psychological
disorders
• Thus the brains appraisal of the
stressor plays a major role in the
body’s response Appraisal –
• As influenced by the based on
biopsychosocial model experience
Notes de l'éditeur
Homeo = similar; Allo = VariableBlood glucose levels are reduced, oxygen levels returned to level
Allo: variable i.e. enables the body to meet internal & external demandsSo there is more internal variability in order to deal with changing conditions
Allo: variable i.e. enables the body to meet internal & external demandsSo there is more internal variability in order to deal with changing conditions
A.Response: thus we are dealing with the stressorA.Load: can result in social dysfunction i.e. consumption exceeds resourcesPhysiological disorders: cardiovascular problems, to Psych: anxiety disorders
A.Response: thus we are dealing with the stressorA.Load: can result in social dysfunction i.e. consumption exceeds resourcesPhysiological disorders: cardiovascular problems, to Psych: anxiety disorders