Did you know that every time you dive tiny bubbles
of gas appear in your blood stream? If you happen to have a stethoscope about
you after a dive, put it on the inside of you're elbow; you can here all
those little bubbles rushing about your bloodstream. These in themselves
are not a huge problem (though a large number of dives can lead to blood
vessels into the bones being blocked, the bone dies and you get a kind of
osteoporosis) but if these bubbles become larger as may happen with a fast
ascent from a dive then you have big problems.
The Bends
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Everybodys favourite nasty. Gas bubbles appear
in the cartilage, and expand causing severe joint pains. The name reputedly
comes from serious cases where the cartilage in the back expands forcing
the victim to "bend" over in pain, not a nice thing to happen to
you.
Lung Damage
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Nasty stuff happens if you hold your breath underwater;
the pressure increase in the lungs caused on ascent can cause serious injury.
The membrane which lies between the air in the lungs may rupture, this
allows air to enter the blood stream, as the diver surfaces the air can
accumulate in major organs like the heart and brain, causing damage or death.
The wall between the lungs and the body cavity may also break such
that air enters the areas around the heart and lungs, the lungs collapse,
it becomes difficult to breath and the heart may stop. The air accumulates
around the neck giving it an interesting "crackerly" feel to it.
Ear Damage
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As anyone who has surface dived in a swimming pool
knows the ears are susceptible to pressure damage. If you go under
water without equalising teh pressure on either side of the ear drum you
start with intense pain. If the pressure is allowed to build up then
the eardrum (a thin membrane separating the outer and middle ear can rupture.
This results in pain, dizziness and nausea, all bad.
Nitrogen Narcosis
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Save the most fun one till last. Nitrogen Narcosis,
when you get beyond a certain depth (~30m in temperate conditions) the nitrogen
in the air, normally an inert gas starts to have an affect similar to that
of alcohol, this may seem like fun but in a dangerous environment the loss
of the ability and think rationally can be a real threat. I
hav heard of people offering their air supply
to passing fish.... However narcosis *is* great fun, and
comes with the added advantage that once you have ascended above
a certain depth the problem goes away, with none of those nasty hangovers,
bonus!
Here's me doing a wonderful demonstration of how
to look very bad underwater. You can't beat the nice pink hired wet suit
and the underwater hairstyle; water has the amazing ability to make even
the most attractive person look like they have been dead in a river for a
week, so I didn't really stand a chance...
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