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Stress Response
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Homeostasis v2.0: A new approach to explaining the stress
response
January 7, 2011
Every person experiences the physiological effects of stress. An
increase in blood pressure, an
upset stomach, focused attention, and increased breathing rate
are all common effects of a stress
response. Whether it is sitting in traffic, being placed on
hold, or filling out confusing tax forms, many
daily activities come with these noticeable changes in body
arousal and behavior. Many people do not
even have to be in a stressful situation to experience these
bodily changes. The anticipation of an
important meeting or deadline, exam, or life event may also
result in the same stress response.
Everyone knows these feelings, but why does this happen?
Through evolution, humans have adapted to environmental
stressors by developing
physiological stress response system. Due to the fact that early
man did not have to worry about paying
off a mortgage or giving an important speech, the stress
response system adapted to various natural
stresses that were common in an uncivilized world. This stress
response system is commonly referred to
as the fight or flight response. When faced with a predator in
the wild, an animal must instantly decide
whether to fight its attacker or flee to save its life. This
automatic response system is very similar in both
humans and animals. The stress response focuses on the bodys
instant need to mobilize its energysupply when faced with a threat
in order to power the muscles most effectively. In civilized
society
where safety is ensured, people do not need to run from
predators (with exceptions, of course) and
more commonly experience stressful situations similar to
anticipating giving a speech or planning for
ones financial future. Even these events may result in the same
feelings as though one were being
chased by a saber-toothed cat. However, this stress response was
naturally intended to be activated for
a short period of time. Chronic stresses,, such as going to a
job that you hate for ten consecutive years,
are very dangerous to the body and may result in several stress
related diseases. For a long time,
researchers thought this stress response was governed by a
process called homeostasis.
Homeostasis seeks to explain the stress response by comparing
the body to a balance. The body
seeks to maintain a balance between internal and external
activities. When an event affects the body,the body must react in
order to counter-act the event. For example, when a person gets
hot, the skin
perspires to moisten and cool itself. Homeostasis relies on two
main ideas; that there is an optimal level
for each bodily function and that some regulatory mechanism at
the site of the event is responsible for
returning the affected system to its optimal level. This
action-reaction way of looking at the stress
response has failed to account for more complex responses from
the body as a whole. First, it fails to
take into account differences in optimal bodily levels in
different environmental settings and second, it
fails to explain the stress response in anticipation of a
stressful event.
A more unified bodily perspective of the stress response built
on the idea of homeostasis is
more effective at explaining this phenomenon. This more unified
perspective looks at bodily responses
as a whole in order to regulate the body and maintain optimal
bodily levels. This concept is known as
allostasis. Allostasis follows that the optimal bodily levels
may be different in different conditions, for
example, from when a person is sleeping and when a person is
running a marathon. Also, allostasis does
not rely on localized regulatory control mechanisms in order to
maintain optimal levels. Allostatic
change occurs on a bodily scale and may involve multiple bodily
systems to restore optimal levels or to
anticipate stressful events. Rather than the skin perspiring in
order to cool in the homeostatic view, the
allostatic view would explain this response by employing
multiple body systems. The allostatic view
would say the skin became hot and then sent impulses through the
nerves to the brain. The brains
regulatory mechanisms then send messages back to the skin to
begin to perspire by drawing moisture
