Humans don’t have fur like many of our ancestors,
but our bodies still have the ability to adapt to cold weather.
However,when pushed these mechanisms can fail leading to an extreme breakdown.
So,what actually happens to your body
and brain when you freeze to death?
Hypothermia occurs when the core body temperature drops
below 37 degrees Celsius,
so in the event that the body is
exposed to extreme cold, within minutes
signals are sent from the skin to the hypothalamus
producing what is known as the Thermoeffector Response.
First, the blood vessels in our skin narrow,
allowing the body to maintain its core temperature by reducing the blood flow
on its surface, known as Vasoconstriction.Additionally,
brown adipose tissue located throughout the body
also activates using high levels of glucose and lipids
to produce heat via a process called non-shivering thermogenesis
But, if all else fails
our body undergoes Shivering Thermogenesis as a last-ditch effort
By constantly contracting our skeletal muscles,our body induces shivering
in an attempt to produce enough heat to prevent hypothermia.
However,if you remain exposed to the cold within 30 minutes
you could get frostbite which is
when your skin and other tissues literally begin to freeze.
Developing ice crystals endanger your cells
by damaging their cell membranes, causing Intracellular Dehydration,
due to water leaking out from them.
The cells then begin to die
and the ice crystals continue to expand,
damaging neighboring cells.
In response, the body tries
to prevent frostbite in our skin through Vasodilation,
which allows increased blood flow to warm the skin cells.
this runs counter to the Thermoeffector Response,
which again works to maintain our core temperature through Vasoconstriction.
As a result,
our body goes through cycles of Vasodilation and Vasoconstriction,
thawing and freezing our skin over and over again
and causing even more damage.
But,our skin isn’t the only spot that will freeze
under extreme cold temperatures.
If you’re in extreme cold, windy weather
your corneas can freeze too,
the protective layer of tears covering the cornea can dry,
making your eyes sensitive to light and causing eyelid spasms.
Luckily,your corneas can thaw if you get yourself
out of the cold quickly,
但是 如果冰冻时间够长的话 会导致永久伤害
but if frozen long enough, you can cause permanent damage.
现在 身体组成 衣物
Now,several factors, including body composition
clothing,temperature and the environment
determine how quickly your core body temperature drops.
For example, heat is lost much more quickly in water than in air.
Those who were submerged in the icy waters after the sinking
of the Titanic may have lasted only 15 minutes,
this is because during the advanced stage
of hypothermia your organs begin to fail,
your breathing rate slows, you lose coordination,
your heart rate begins to slow down,
and your body even stops shivering.
One of the last symptoms of advanced stage hypothermia
is delirium, a survey of cases in which
death was caused by hypothermia found that in
25% of the cases,
the victims had undressed before they died.
In one case, victims had neatly folded their clothes
beside them and froze to death in the snow.
Why would this happen? One theory
is that the brain damage that results from the extreme cold
causes people to think that they’re burning up,
so they strip naked and cool down.
Another theory suggests that the muscles that cause Cutaneous
Vasoconstriction in our blood vessels get exhausted and cause blood
from our core to rush to the surface of our body,
resulting in a hot flash. This is all pretty bleak,
but if you find someone who appears to be frozen to death,
you may want to warm them up.
An aptly named paper,
No One is Dead Until Warm and Dead,
chronicles a patient with hypothermia caused by drowning with no signs of life.
This patient was successfully resuscitated
with a 3-hour bypass surgery used to warm his body.
Though parts of his body required amputation,
in 11 weeks he successfully recovered with normal neurological function.
Just remember, when the temperature starts to drop,
do everything you can to stay warm,
because your body can only do so much to fight the extreme cold.
So what are the techniques to help your body survive freezing to death?
We made a video of step-by-step
strategies to stay alive if you’re ever trapped in the extreme cold.
Click here to learn the life-saving,
but also gruesome things you need to know
to avoid hypothermia and freezing to death.
With climate change causing extreme weather
we may all need this info in the future, and
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