blood carbonate levels under water (should I talk to my professor? )

[chenge4444]

Hi all,

I got this question on my test:

"Marco tries to hide at the bottom of a swimming pool by breathing in and out through a long garden hose (2 feet in length), which greatly increases his dead space. What happens to the bicarbonate level in his arterial blood and why?"

 

I think breathing under water would increase his arterial bicarbonate levels. Is this correct? 90% of CO2 is the blood is transported as bicarbonate ions. My professor thinks this is incorrect because she said that blood CO2 is only 40nm and blood HCO3 is 24 mM, so even doubling the amount of arterial CO2 would not make any differences. But I think 40nm is the concentration of H+, the concentration of arterial CO2 is actually 21 mM.

 

My professor and I exchanged about 4 or 5 emails each. I don't want to waste her time unless I'm certain that my understanding is correct.

Edited May 23, 2017 by chenge4444

[studiot]

Well I think you are both wrong.

 

The maximum safe limit for a snorkel is 16 inches.

 

https://physics.le.ac.uk/journals/index.php/pst/article/viewFile/627/442

 

I suggest you google this subject and also

 

Carbon dioxide and diving as there is much more to the the biochemistry as well

 

https://www.diveassure.com/wp-content/uploads/2015/05/Diving-and-Carbon-Dioxide.pdf

[John Cuthber]

Well I think you are both wrong.

 

 

I think that , if one says the [HCO₃^-] rises, and the other says it falls, it's pretty damned certain that one of them is right.

The point of the question is that, because it leaves you with too much CO₂ it isn't safe. So telling them it's a poor snorkel isn't helpful- they know that.

 

Not flushing out the CO₂ will certainly raise the amount of CO₂ in the air, and hence the blood.

The next question is what happens to that CO₂?

Whatever the pH, adding more carbon is going to increase the bicarbonate concentration- where else can it go? Some of it has to dissociate and form bicarbonate. (The pH will dictate the ratios of HCO₃^- to CO3^- and HCO₃^- to CO₂ )

The numbers don't really matter.

[studiot]

I think that , if one says the [HCO₃^-] rises, and the other says it falls, it's pretty damned certain that one of them is right.

The point of the question is that, because it leaves you with too much CO₂ it isn't safe. So telling them it's a poor snorkel isn't helpful- they know that.

 

Not flushing out the CO₂ will certainly raise the amount of CO₂ in the air, and hence the blood.

The next question is what happens to that CO₂?

Whatever the pH, adding more carbon is going to increase the bicarbonate concentration- where else can it go? Some of it has to dissociate and form bicarbonate. (The pH will dictate the ratios of HCO₃^- to CO3^- and HCO₃^- to CO₂ )

The numbers don't really matter.

 

 

I think the point is that a dead or seriously damaged Marco due to the physics of the breathing tube, will not have normal biomedical responses.

Edited May 23, 2017 by studiot

[Raider5678]

The maximum safe limit for a snorkel is 16 inches.

I'm a layman here, so forgive me for asking, but why is there a limit?

Edited May 23, 2017 by Raider5678

[StringJunky]

I'm a layman here, so forgive me for asking, but why is there a limit?

The longer the tube, the less exhaled air gets expelled from the tube, so you end up re-breathing it. You can't replenish the snorkel tube, beyond that length, with fresh air... the dead space is too big. Increasing pressure on the lungs from going deeper has an effect on the efficiency as well.

 

https://www.snorkelingonline.com/pages/why-are-snorkel-tubes-so-short

[John Cuthber]

 

 

I think the point is that a dead or seriously damaged Marco due to the physics of the breathing tube, will not have normal biomedical responses.

With no indication of the diameter of the tube, or the work rate, it's impossible to say if it's safe or not.

If, for example, he's using this method to hide from an attacker, it may well prolong his life.

If it fails then the question of what the blood HCO3 levels in his corpse are is still valid.

 

 

If he breathes in through his mouth + out through his nose, the problem largely goes away.

[Raider5678]

The longer the tube, the less exhaled air gets expelled from the tube, so you end up re-breathing it. You can't replenish the snorkel tube, beyond that length, with fresh air... the dead space is too big. Increasing pressure on the lungs from going deeper has an effect on the efficiency as well.

 

https://www.snorkelingonline.com/pages/why-are-snorkel-tubes-so-short

Alright.....

And if they exhale from their nose?

[StringJunky]

Alright.....

And if they exhale from their nose?

As JC said, you would be OK but other factors would come into play as you go deeper which are mentioned in that link.

[John Cuthber]

There would be a problem if you were at any great depth because the water pressure would squash the air out of your lungs and you wouldn't be able to breathe in. A long horizontal tube to a "diver" not far under water who breathed out through their nose would be much less of a problem- as long as the pipe was wide enough- but pretty pointless.

 

Meanwhile back at the topic...