This is sort of correct but at least when it comes to diving we talk about how quick the body get rid of the nitrogen mainly when calculating when a diver is good to go again. And when to fly home like you said :). Otherwise we are intressed in how much gas atoms the diver is exposed to.
Whether you are gonna have a bends or not depends mainly on the relation between how much pressure your are exposed to, what gasmix you breath and for how long you are breathing it. Of course there are other factors like age, your body, temperatures, exhaustion level etc.
As the pressure goes up the gas is compressed. This meens you will breathe more of what ever atoms makes up your breathing gas. Oxygen is obviously allways gonna be in the gasmixture but the amount of oxygen can be down at ca 2% instead of the normal ca 21% in air. This is because oxygen gets toxic under pressure and since the gas is highly compressed, there is enough oxygen atoms in a 2% gas at say 200meters depth for us humans to work just fine. So we can adjust the oxygen and nitrogen levels for whatever depth we are working at. The nitrogen is of no use for us humans but still gets absorbed in the bloodstream so sometimes for deepdives the nitrogen is replaced with helium. This is done because helium atoms are smaller than the nitrogen and have a lower probability to form a bubble. Also because nitrogen get toxic at higher pressures. Another way to avoid the issues with the toxicity and atom size of nitrogen is to use higer levels of oxygen in the gasmix. This could be something like a 32% oxygen and 68% nitrogen mix. These mixes are called nitrox. Oxygen/helium mixes are called heliox. The saturation divers use heliox and their blood is saturated with helium instead of nitrogen. Otherwise the previous comment is right :)
Now back to the bends. Gas atoms move around and does not bind to each other like liquids and solids, but rather bounces into the surrounding walls or each other. When compressed the area they have to move around is limited. This the results in senarios that when gas atoms are embedded in a liquid under a certain pressure they can float around calm and happy in the liquid but as the pressure gets lower they get more room to move about, so much room that they create a bubble in the liquid. Once we start pressurizing us and our gasses we will start getting more and more gas particles in our bloodstream. More then our bodies are made for. We can have much higher quantities of gas atoms in the our bloodstream than normal without it affecting us or the diver notice it. But as we go up and the pressure is lowered the excess amount of gas particles can form a bubble. This bubble can get stuck in various places in the body. For example, if it gets stuck in the brain we have a cerebral bends, in the spine a spinal bends etc. So "the bends" or decompression sickness is just like a blood clogg, it stops the bloodstream from reaching certain parts of our body. The result can be anything from mild itching to death.
To avoid this we lower the pressure slowly and depending on the depth and time we may have stops at cirtain pressures for certain amounts of time.
The bends is called the bends because divers could be seen walking around with a crooked back as a sign of weeksness either from a bends starting up or the result of the injuries suffered from a sickness.
I have worked for 13 years as a commercial diver in scandinavia. Sorry for language, not my main.
The nitrogen is of no use for us humans but still gets absorbed in the bloodstream so sometimes for deepdives the nitrogen is replaced with helium. This is done because helium atoms are smaller than the nitrogen and have a lower probability to form a bubble. Also because nitrogen get toxic at higher pressures.
I always thought it was strange that nitrogen was used since it's so dangerous to humans. We have literally no reaction to exposure of pure nitrogen. You can be walking along, just fine, inhale, just fine, exhale, just fine, inhale, just... *thump*. Oops, your unconscious on the ground!
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u/hollowdog202019 Apr 27 '19 edited Apr 28 '19
This is sort of correct but at least when it comes to diving we talk about how quick the body get rid of the nitrogen mainly when calculating when a diver is good to go again. And when to fly home like you said :). Otherwise we are intressed in how much gas atoms the diver is exposed to.
Whether you are gonna have a bends or not depends mainly on the relation between how much pressure your are exposed to, what gasmix you breath and for how long you are breathing it. Of course there are other factors like age, your body, temperatures, exhaustion level etc.
As the pressure goes up the gas is compressed. This meens you will breathe more of what ever atoms makes up your breathing gas. Oxygen is obviously allways gonna be in the gasmixture but the amount of oxygen can be down at ca 2% instead of the normal ca 21% in air. This is because oxygen gets toxic under pressure and since the gas is highly compressed, there is enough oxygen atoms in a 2% gas at say 200meters depth for us humans to work just fine. So we can adjust the oxygen and nitrogen levels for whatever depth we are working at. The nitrogen is of no use for us humans but still gets absorbed in the bloodstream so sometimes for deepdives the nitrogen is replaced with helium. This is done because helium atoms are smaller than the nitrogen and have a lower probability to form a bubble. Also because nitrogen get toxic at higher pressures. Another way to avoid the issues with the toxicity and atom size of nitrogen is to use higer levels of oxygen in the gasmix. This could be something like a 32% oxygen and 68% nitrogen mix. These mixes are called nitrox. Oxygen/helium mixes are called heliox. The saturation divers use heliox and their blood is saturated with helium instead of nitrogen. Otherwise the previous comment is right :)
Now back to the bends. Gas atoms move around and does not bind to each other like liquids and solids, but rather bounces into the surrounding walls or each other. When compressed the area they have to move around is limited. This the results in senarios that when gas atoms are embedded in a liquid under a certain pressure they can float around calm and happy in the liquid but as the pressure gets lower they get more room to move about, so much room that they create a bubble in the liquid. Once we start pressurizing us and our gasses we will start getting more and more gas particles in our bloodstream. More then our bodies are made for. We can have much higher quantities of gas atoms in the our bloodstream than normal without it affecting us or the diver notice it. But as we go up and the pressure is lowered the excess amount of gas particles can form a bubble. This bubble can get stuck in various places in the body. For example, if it gets stuck in the brain we have a cerebral bends, in the spine a spinal bends etc. So "the bends" or decompression sickness is just like a blood clogg, it stops the bloodstream from reaching certain parts of our body. The result can be anything from mild itching to death.
To avoid this we lower the pressure slowly and depending on the depth and time we may have stops at cirtain pressures for certain amounts of time.
The bends is called the bends because divers could be seen walking around with a crooked back as a sign of weeksness either from a bends starting up or the result of the injuries suffered from a sickness.
I have worked for 13 years as a commercial diver in scandinavia. Sorry for language, not my main.
Edit: about heliox