blacknet
Contributor
Hello,
Am told that the average human body, at sea level, contains about a liter of nitrogen.
Ed
Am told that the average human body, at sea level, contains about a liter of nitrogen.
Ed
Fish and decompression
- Thread starter Liquid
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Dr Deco
Contributor
- Messages
- 2,384
- Reaction score
- 96
- # of dives
- I just don't log dives
How much volume in inert gas bubbles to provoke DCS? That depends on where they are located. Probably little volume is needed if it is in a crucial area within the spinal cord. Joints and tendons might require more.
The answer is not really known.
Dr Deco
The answer is not really known.
Dr Deco
OP
I think rochn ment the amount of MOLs of N2 per a given volume of tissue of certain kind, when going from certain surounding pressure to surface pressure.
And my answer would be:
Same as the Doc's.
It depends on a LOT of factors. Ive been going through some studies on this, and studies about other related things. It varyies from one location to another, from one tissue to another. In the slower tissues (such as fat, the bone's inside which I cant remeber the english name of) it usualy takes less N2, as their ability of super-saturation is less than that of the quicker tissues. You can complicate it further, by acknoledging the fact that those tissues half time is so big that it is hardly likely to super-saturate it in recreational dives. Than there are the intermeidiate tissues. Than there is the location- There are certain spots which bubbles just "LOVE" to hang in. Usualy it is a place between several tissues, so bubbles coming out of there "travel" untill they reach those spots. Add the fact that two bubbles that meet like to make a bigger bubble (I just love "bubble mechanics"!!!) and you get a whole complex mechanism. this is why we have dive tables and computers. There is a relatively new model, that takes those things into consideration- the "RGBM" model (Reduced Gradient Bubble Model).
Try looking at: http://www.abysmal.com/pages/articles/online_with_RGBM.html
they have a great library of articles on this subject. Check also my thread named "RGBM formula"
Damn it! I just found out you'v given me those links in the first place IMHO. Hm. have you read what's on abbismal?
they really do hold some great matterial over there. was very helpfull, and I am still going through it. The VPM was a new site for me, and held some nice information as well.
And my answer would be:
Same as the Doc's.
It depends on a LOT of factors. Ive been going through some studies on this, and studies about other related things. It varyies from one location to another, from one tissue to another. In the slower tissues (such as fat, the bone's inside which I cant remeber the english name of) it usualy takes less N2, as their ability of super-saturation is less than that of the quicker tissues. You can complicate it further, by acknoledging the fact that those tissues half time is so big that it is hardly likely to super-saturate it in recreational dives. Than there are the intermeidiate tissues. Than there is the location- There are certain spots which bubbles just "LOVE" to hang in. Usualy it is a place between several tissues, so bubbles coming out of there "travel" untill they reach those spots. Add the fact that two bubbles that meet like to make a bigger bubble (I just love "bubble mechanics"!!!) and you get a whole complex mechanism. this is why we have dive tables and computers. There is a relatively new model, that takes those things into consideration- the "RGBM" model (Reduced Gradient Bubble Model).
Try looking at: http://www.abysmal.com/pages/articles/online_with_RGBM.html
they have a great library of articles on this subject. Check also my thread named "RGBM formula"
Damn it! I just found out you'v given me those links in the first place IMHO. Hm. have you read what's on abbismal?
they really do hold some great matterial over there. was very helpfull, and I am still going through it. The VPM was a new site for me, and held some nice information as well.
The Chairman
Chairman of the Board
There is not enough N2 in any one lung full to saturate our tissues. This supersaturation occurs only with repetitive breathing under pressure. This occurs with SCUBA, where the lung tissues are repeatedly exposed to abnormally high PP N2. Breath holding can not provide the sustained high partial pressures of N2, due to the reduced PP as the N2 is absorbed. The law of diminishing returns keeps supersaturation to a minimum.
Cool... clear as mud! :tease:
Cool... clear as mud! :tease:
danreind
Guest
Ofcourse the amount of N2 in the lungs is limited and probably can't cause much in the way of supersaturation (what about fast tissues of small volume though?). My understanding is that whales employ an additional DCS prevention mechanism. I seem to recall that some whales collapse their lungs, forcing the remaining air into their tracheal areas where gas exchange is minimal (this means that whales are diving solely on the oxygen stored in their muscles - which favors the use of myoglogin over hemoglobin as I understand). Lungs are then reinflated upon surfacing. I can't say this with confidence since I don't have a reference, but I'm sure I ran into this somewhere in my undergrad.
I wonder about the effect of repeated dives. I know one paleontologist was claiming to find evidence of decompressive bone decay (dysbaric osteonecrosis) in a species of diving dinosaur, although I'd personally be a little leary of misinterpreatation for such old bones. Isn't a sample size of one statistically significant in paleontology? - just kidding
Cheers,
Dan
I wonder about the effect of repeated dives. I know one paleontologist was claiming to find evidence of decompressive bone decay (dysbaric osteonecrosis) in a species of diving dinosaur, although I'd personally be a little leary of misinterpreatation for such old bones. Isn't a sample size of one statistically significant in paleontology? - just kidding
Cheers,
Dan
OP
danreind,
I belive what you mean is the pumping of blood to the small blood vessesls that suround the smallest parts of the lungs (I dont know the english names) that I mentioned earlier. It happens when lungs drop below a certain cruicial volume it must obtain, since you can not completly empty the lungs. The blood provides some volume in the lungs and keep them in working order. This also happens in Humans, and this is what enables skin divers to reach as deep as 150 meters.
I belive what you mean is the pumping of blood to the small blood vessesls that suround the smallest parts of the lungs (I dont know the english names) that I mentioned earlier. It happens when lungs drop below a certain cruicial volume it must obtain, since you can not completly empty the lungs. The blood provides some volume in the lungs and keep them in working order. This also happens in Humans, and this is what enables skin divers to reach as deep as 150 meters.
Dr Deco
Contributor
- Messages
- 2,384
- Reaction score
- 96
- # of dives
- I just don't log dives
Dear Readers:
This is another unresolved question. I believe however that it all comes down to the point that the lungs of these animals just does not contain enough nitrogen to cause DCS in the tissues. Added to this is the closure of lung blood vessels, and the nitrogen is further dropped.
Dr Deco
This is another unresolved question. I believe however that it all comes down to the point that the lungs of these animals just does not contain enough nitrogen to cause DCS in the tissues. Added to this is the closure of lung blood vessels, and the nitrogen is further dropped.
Dr Deco
Similar threads
