What happens to non-respiratory gases in the lungs?

[Amaterasu21]

TL;DR Summary

What happens to nitrogen, argon etc. in the alveoli?

Hi, a thought just occurred to me.
We all learned in school that oxygen diffuses from the air in the alveoli into the blood, and carbon dioxide diffuses from the blood into the air to be breathed out. But they never mention nitrogen, argon or any of the other gases in the air! Does something prevent them from diffusing across? Given that these are all relatively small non-polar molecules I'd imagine they'd all diffuse easily through the alveolar and capillary membranes, so probably not that. Or is the partial pressure of these gases dissolved in the blood identical to that in the air, leading to no diffusion gradient? In which case, blood contains way more dissolved nitrogen than I thought!

A second thought too: since the concentration of carbon dioxide in our atmosphere is going up, that must be reducing the concentration gradient for CO2 between the air and our deoxygenated blood. Does that mean carbon dioxide diffusion is becoming less efficient and thus our burning of fossil fuels is inhibiting our ability to remove wastes and control blood pH? I suppose it must be, but is this a negligible effect or a real concern?

 

[jim mcnamara]

Here is an extreme example: an underwater landslide vigorously disturbed Lake Nyos in the Cameroons. Vast volumes of released CO₂ killed more than 1000 people. Humans cannot adapt that fast.

https://en.wikipedia.org/wiki/Lake_Nyos_disaster

Going up in elevation:
Humans respond to lower partial pressures of O₂ by slowly increasing hematocrit (hemoglobin levels in blood) to compensate. So we can adapt to very slow changes. Andean people have genetic changes to accommodate lower partial pressures of O₂ at elevation > 2700m

You may want to check out Decompression sickness ( bends) - another partial pressure change of gases: nitrogen in this case

https://www.ncbi.nlm.nih.gov/books/NBK537264/

So, what you thought is pretty reasonable, except maybe for the rapidity of change.

 

[256bits]

Summary: What happens to nitrogen, argon etc. in the alveoli?

Or is the partial pressure of these gases dissolved in the blood identical to that in the air, leading to no diffusion gradient? In which case, blood contains way more dissolved nitrogen than I thought!

There is the solubility of the gas in blood to take into account.
You can look at these 2 sites to try and make some heads and tails of it.

wiki has a list of ingredients in the blood - no mention of Argon, perhaps it it too faint to list??
https://en.wikipedia.org/wiki/List_of_human_blood_components

This lists the solubility of inert gases in blood, although its from 1981 ( 40 years ago ) and somewhat incomplete, ...
https://www.researchgate.net/publication/16933250_Solubility_of_inert_gases_in_biological_fluids_and_tissues_A_review
At the end conclusion they write,
This compilation has attempted to summarize the equilibrium property of gas molecules most important to hyperbaric research and operations. How much gas can actually dissolve in the body'? Except fbr the well-studied clinical anesthetics cyclopropane, nitrous oxide. and halothane. and the common radiotracers krypton and xenon. the question remains unanswered. Of the more than -500 measurements tabulated in this repoft only a single determination was found that pertains directly to the hyperbaric environment (59). The discrepancies among different studies frequently exceeds a factor of 2. far too imprecise fbr most predictive work. The dearth of data is especially prominent for the peripheral tissues most at risk in hyperbaric exposures-i.e.. joints. ears, bones. and spinal cord-and fbr the gases most likely to be used-i.e.. nitrogen. helium. argon. and hydrogen.

 

[Amaterasu21]

That all makes sense - the bends, of course! Thank you!