Mr T's Wild Freedive

[IncreaseMyT]

Thats what I mean I am here typing off the top of my head and you guys didn't even realize this occurred. If you understood free diving, I wouldn't have to explain every single post down to every single word.

Congratulations, I have explained in detail many different things that are negative to free diving and taking gas from a scuba diver.

You have managed to funnel everything I said, down to word play. You guys are so smart, I wish I could be more like you.

 

[IncreaseMyT]

We are in the free diving forum right?

 

[saxman242]

Thats what I mean I am here typing off the top of my head and you guys didn't even realize this occurred. If you understood free diving, I wouldn't have to explain every single post down to every single word.

Congratulations, I have explained in detail many different things that are negative to free diving and taking gas from a scuba diver.

You have managed to funnel everything I said, down to word play. You guys are so smart, I wish I could be more like you.

Words have meaning. Explaining that something magical was happening during free diving that violates the laws of physics isn't a matter of word play. If we are going to have a discussion about what is going on and what the risks are, it is helpful to at least be in the general direction of what is actually going on.

 

[Storker]

Thats what I mean I am here typing off the top of my head and you guys didn't even realize this occurred. If you understood free diving, I wouldn't have to explain every single post down to every single word.

Congratulations, I have explained in detail many different things that are negative to free diving and taking gas from a scuba diver.

You have managed to funnel everything I said, down to word play. You guys are so smart, I wish I could be more like you.

I'll try my very best to be civilized here. For whatever that's worth.

You have some - let's say "rather unconventional" ideas about what happens with gas while we're diving. Given that you more or less consistently use completely wrong words for the phenomena you're talking about, it's very difficult to discern if you're way out there on left field, or if you just suffer from some moderate misunderstandings which, when you express them, are dramatically exacerbated by your complete failure to call things by their proper names. It's as if I were trying to explain how a fire starts by talking about wind.

This is physics, it's chemistry, it's biology and it's physiology. In those sciences, words have very specific meanings, and calling mass transfer "compression" or - to use my example about fires - calling the rising of smoke from a fire "wind" will at best create confusion.

I'd really recommend you to read up on high school physics and develop an understanding of the phenomena you're posting about. Yeah, and to tone down the condescension in your posts. Because, as I've already said, you're well into "not even wrong" territory here.

 

[IncreaseMyT]

It is magical according to physics. The oxygen comes back in to your lungs the nitrogen does not

Until you guys show that you have any clue about the effect of free diving on mammals, I’m out

At one point scientist said we couldn’t go past 40 feet

 

[Storker]

It is magical according to physics.

No, it is not. It can all be explained using high school and freshman college level science.

The oxygen comes back in to your lungs the nitrogen does not

Ok, here's another case where you've got it bass-ackwards. No matter if the person in question is freediving or on scuba, nitrogen is physically dissolved in the blood while oxygen is predominantly captured by the diver's red blood cells for transport to the tissues. In the tissues, nitrogen is absorbed and stays there while oxygen is metabolized into CO2. The CO2 is transported back to the lung alveoli, where it's transferred to the gas in the alveoli. The nitrogen stays in the tissues until the diver starts to ascend, at which time it transfers from the tissues into the blood and is transported back to the lung where it transfers to the gas in the alveoli.

Now, for a scuba diver the O2 won't have time to deplete dramatically and the CO2 won't have time to accumulate dramatically because we breathe continuously. So the expired air contains some 17% O2 and some 4% CO2, and WRT lung gas composition we're pretty much the same as at the surface. A freediver doesn't ventilate their lungs, so they experience a more serious depletion of O2 and a more serious accumulation of CO2. Given the relatively short duration of a freedive and the rather slow diffusion of nitrogen from the alveoli to the blood, the amount of nitrogen transferred from the lungs to the blood (and other bodily fluids, cue General Jack D. Ripper) is rather minute, from a total volume perspective. Unless we're talking about repeated freedives (Taravana syndrome), where the amount of nitrogen dissolved in the tissues becomes significant from a DCS POV, but far from necessarily from a lung gas composition POV. And it's the combination of low FO2 in the lungs and decreasing P leading to a too low pPO2 which is responsible for shallow water blackout for freedivers.

Your apparent complete confusion over gas compression, gas transport and the basic physics and physiology of diving doesn't strengthen your case.

 

[IncreaseMyT]

Henry’s Law and Freediving
As we’ve seen, as you descend on a dive, the increased pressure causes the volume of air in your lungs to decrease. But as this happens, the partial pressure of the air inside your lungs increases. This means that there is a greater concentration of oxygen and other gases in our lungs than there is in the blood. It is explained in another law – Henry’s Law:

“At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.”

Diffusion is the movement of gas molecules from a region of higher concentration to a region of lower concentration until they are equal. This means that the deeper you go, the more oxygen will dissolve into your blood. Then, as you ascend, the volume of air inside your lungs increases, oxygen comes out of the blood, back into your lungs.

As the greatest pressure changes take place between the surface and a depth of 10m, this is where proportionally more oxygen comes out of the blood. Consequently, this is why you are at the greatest risk of a blackout, especially when you are already running low on oxygen at the end of your dive.

Effects of Pressure and Depth

Please educate yourself you sound silly.

 

[almostDIR]

the oxygen transport is explained very well in literature including some scuba books. For example the Deco for Divers by Mark Powell.

hemoglobin carries most of the oxygen transport in bloodstream and only couple of % is carried in blood plasma whereas almost all nitrogen is carried in plasma. The plasma dissolving is so much more ineffective that the nitrogen moves much slower which also explains why one does not fully saturate ones tissues almost instantly with nitrogen when descending to certain depth like it would happen if nitrogen would been carried around the body the same way oxygen does.

the gas contents in lungs is btw nowhere near the atmospheric distribution of gases. Much less oxygen, more water vapor and carbon dioxide, etc

OK STORKER ALREADY ANSWERED TO THIS WHILE I WAS WRITING

 

[IncreaseMyT]

At a depth of 10m we need more oxygen in our bloodstream than at 100m, because the pressure of the water all around makes the oxygen more potent. So the most tricky part of a deep dive is the last stage of the ascent, when there is the risk of a shallow water black-out as the pressure fades and the oxygen levels in our tissues suddenly drop.

In the very early days of free-diving, physiologists were pretty convinced that people couldn’t go beyond about 30 or 40 metres. They’d drawn their graphs as scientists and they’d worked out what they saw. They worked out what they understood about the human body and the effects of pressure on it and they said: “Well, look, your lungs are going to be crushed and you’re going to be spitting blood by the time you’re at 30 or 40 metres. So there’s no way that you can do this on breath-hold diving. It just can’t be done.”

As a free diver, going deeper, you’re just squeezing those last dregs of oxygen out of your blood stream and trying to subsist on much lower levels than any human being normally ever does. And you go into this sort of strange balance between the pressures that exist at depth temporarily helping to support you while your breath-holding is threatening your life. It’s really a very, very precarious balance and it requires you to enact some very weird and very strange and not all that well understood physiological feats just to stay alive. The depth records for human free diving now are quite absurd: not tens but hundreds of metres.

People have rough models of how that is achieved. It’s not a total mystery – but clearly there’s more going on than we fully understand. What I found really fascinating working on this project was that the free divers and non-scientists that participate in free diving talk about this sort of quite holistic experience of being at one with the ocean and this great feeling of well-being. To a physiologist, that’s the euphoria of oxygen starvation and hypoxia, which is not great, but for the free divers themselves this is part of the experience. It’s impossible for them to disentangle that from the diving itself.

Free divers have long defied science – and we still don't really understand how they go so deep

Abstract
This report examines the evidence for the presence of oxygen stores in the lungs, blood and systemic musculature of diving mammals, the modifications in the respiratory functions of blood that may be important in utilizing the lung and blood oxygen stores, and the potential importance of the oxygen stores and the respiratory functions of blood in supporting short-duration, aerobic dives. Increasing oxygen stores by increasing lung volume does not occur in diving mammals. The long-duration diving whales have small lung volumes which results in lung collapse during dives and the seals dive following partial expiration which produces the same effect. The short-duration diving dolphins, porpoises and rodents have lung volumes comparable to terrestrial mammals, dive following inspiration and appear to use the lungs as an oxygen store. Adaptations in the oxygen affinity of the blood parallel the modifications in lung volume. Where the lungs do not represent a potential oxygen store the oxygen affinity is low, maximizing the unloading of oxygen while maintaining a high tissue oxygen tension. Where the lungs do represent an oxygen store, the affinity is high, maximizing the uptake of oxygen from the alveolar space. Increases in the concentration of respiratory pigment in the blood and in muscle are important adaptations in diving mammals. The blood oxygen stores in diving mammals vary from near normal to over three times normal for terrestrial mammals while the muscle oxygen stores vary from near normal to nearly ten times normal. The degree to which the blood and muscle oxygen stores are increased can be equated to the duration of the dive and demands for oxygen; longer duration divers and those with higher metabolic demands have greater oxygen stores than divers that remain submersed for shorter periods or have lower rates of oxygen utilization.

Respiratory adaptations in diving mammals. - PubMed - NCBI

 

[almostDIR]

Gases dissolve from high partial pressure to low partial pressure trying to create an equilibrium where the partial pressures are the same. This is also how the lungs work: the oxygen goes from higher partial pressure to lower partial pressure (normally from air in alveoli to the bloodstream) and the carbon dioxide normally goes the other way around (smaller CO2 partial pressure in alveoli so it diffuses from bloodsteam to the air in alveoli) . So when freediving the oxygen is consumed from the lungs until the partial pressures are the same between the bloodsteam and alveoli... higher ambient pressure does not have much to do in this because it affects both the lungs and the bloodstream the same way