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What is it?
Hypothermia occurs when a person's
normal body temperature of around 37°C
(98.6°F) drops below 35°C (95°F).
It is usually caused by being in a cold
It can be triggered by a combination of
things, including prolonged exposure to
cold (such as staying outdoors in cold
conditions or in a poorly heated room for a
long time), rain, wind, sweat, inactivity or
being in cold water.…read more

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There are different types of hypothermia, which
depend on how quickly the body loses heat.
Acute or immersion hypothermia occurs
when a person loses heat very rapidly, for
example by falling into cold water.
Exhaustion hypothermia occurs when a
persons body is so tired it can no longer
generate heat.
Chronic hypothermia is when heat loss
occurs slowly over time. This is common in
elderly people living in a poorly heated
house, or in people sleeping rough.…read more

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When your body gets cold, the normal
response is to warm up by becoming more
active, putting on more layers or moving
But if exposure to the cold continues, your
body's automatic defence system will try
to prevent any further heat loss by:
­ shivering (which keeps the major organs at
normal temperature),
­ restricting blood flow to the skin
­ releasing hormones to generate heat.…read more

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Core temperature is a reflection of
the balance between heat production
and heat loss
Mammals Think about SA:vol ratio,
amount of fat and fur
2 types of thermoreceptors -
­ Central in hypothalamus ­ regulates
core temp
­ Peripheral in skin measures skin temp.…read more

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Controlled by..
The hypothalamus controls
thermoregulation via increased heat
conservation (peripheral vasoconstriction
and behaviour responses) and heat
production (shivering and increasing levels
of thyroxin and adrenalin).
Alterations of the CNS may impair these
The threshold for shivering is 1 degree
lower than that of vasoconstriction and is
considered a last resort mechanism by the
body to maintain temperature.
The mechanisms for heat preservation
may be overwhelmed in the face of cold
stress and core temperature can drop
secondary to fatigue or glycogen…read more

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