High Altitudes Have O2!**

[M.D. Holloway]

Many believe that there are less oxygen levels at high temperatures which makes mountain climbing difficult. That is actually not the case. The reason why it is difficult to breathe at high altitude has to do with a reduction*of pressure. Our respiratory systems require external pressure*(partial pressure) to work.

Here are a couple of cool sites to check out:

The Composition of Earth’s Atmosphere With Elevation | MrReid.org

https://www.irunfar.com/into-thin-air-the-science-of-altitude-acclimation

[island911]

Cool stuff.

I would have put the height on the Y-axis, but still good.

But where is the massive amounts of man-made CO₂ ?

[flatbutt]

Originally Posted by island911

But where is the massive amounts of man-made CO₂ ?

LA county?

[Evans, Marv]

When I worked on the Sierras and came home after 3 to 4 months living, hiking, & climbing at 10 - 13K feet, I noticed how easy aerobic activity was at sea level. i once went to the doctor after coming out of the mountains and gave a blood sample. The doctor commented my red blood count was sky high and asked if I might have an idea of the reason. He understood after I explained I'd been living at a high altitude.

[pwd72s]

Yep, same percentages of gases as at sea level...just less volume because of less pressure. "Thin air" is an accurate term.

[masraum]

Originally Posted by M.D. Holloway

Many believe that there are less oxygen levels at high temperatures which makes mountain climbing difficult. That is actually not the case. The reason why it is difficult to breathe at high altitude has to do with a reduction*of pressure. Our respiratory systems require external pressure*(partial pressure) to work.

Here are a couple of cool sites to check out:

The Composition of Earth’s Atmosphere With Elevation | MrReid.org

https://www.irunfar.com/into-thin-air-the-science-of-altitude-acclimation

Absolutely correct about the reduction of pressure. And maybe partial pressure has something to do with being able to absorb what's in the air. But there is also less oxygen available because there's less air available. The ratio of constituent gases is roughly the same, but at 15k feet, the air pressure is about half what it is for most of us. And when the pressure is that much lower, the density of air decreases by what looks like about 40% (@15k ft). I would think that means that you've got 40% less oxygen available (unless you're turbo charged).

[LWJ]

Living in Boulder for a while I certainly noticed this. But, when I came back to Willamette Valley Oregon, I could run for MILES!

[Pazuzu]

Originally Posted by masraum

I would think that means that you've got 40% less oxygen available (unless you're turbo charged).

Shhhh...it's not the actual number of oxygen atoms entering your lungs each breath that's important to the difficulty of mountain climbing, it's the percentage of oxygen atoms to other gas atoms per cubic meter that's important.


At least to the OP...

[svandamme]

I would think if there is less pressure; there will be less O2 per cubic meter of air.
eg the level of O2 is lower per given volume

The level of other molecules will also be lower.. the ratio should be similar but you might get a slightly different ratio because lighter molecules will be more prevalent then heavier molecules... but that would not be to a degree it really matters for breathing


Also, because pressure is lower, the O2 exchange in the lungs will be less effective.
Think air cooled engines... Air cooling works less effective then water cooling because in essence there are less molecules going past the heat exchanger surfaces.

The fan increases that pressure.
Also the oil pump increases the oil pressure at the oil cooler
higher pressure means more atoms at the exchanger

Same with lungs.

In any case, I would still state that its harder to breathe because there is less O2 up there... That is not an incorrect statement
At least not per volume..

Total O2 up there?
wel the circular diameter of the athmosphere is much bigger so maybe total O2 for the entire altitude is similar.. vs at the ground.. it's just spread out more?
But for breathing that is pretty much irrelevant.

[red 928]

less pressure results in a less
dense atmosphere so less oxygen by volume
and less oxygen contained in each breath
what I find surprising is that we are having a
conversation to clarify something I
thought was so obvious

[GH85Carrera]

Yea, less oxygen, less nitrogen, less carbon dioxide and just less air up high. Ratios may be the same, but just of them. Duh.

[masraum]

Originally Posted by svandamme

Also, because pressure is lower, the O2 exchange in the lungs will be less effective.

Originally Posted by red 928

less pressure results in a less
dense atmosphere so less oxygen by volume
and less oxygen contained in each breath
what I find surprising is that we are having a
conversation to clarify something I
thought was so obvious

Lubey is a VERY smart fella, so I suspect we may be misunderstanding what he was trying to say.

I do think that at least part of the issue is that each lung full of air will contain less oxygen. But the partial pressure of oxygen in the air vs blood stream will be different than at or near sea level. Therefore, it's possible that our lungs/blood will have a much harder time taking in what oxygen IS in the lung full of air.

Partial pressure relates to the pressures of the constituent gases in a mixture and how that amount of gas would relate to the overall volume of the mixture, IIRC.

It's the reason that carbonated beverages go flat when they are opened, and why when they are really cold, they lose that carbonation more slowly than when they are warm. I assume opening a soda or beer at mountaintop atmospheric conditions would probably be a lot more exciting than opening one at sea level.

I hadn't previously read this article because it was next to the image, and I assumed it was part of the link to the image or something.

Originally Posted by M.D. Holloway

https://www.irunfar.com/into-thin-air-the-science-of-altitude-acclimation

But this article does go into detail about the partial pressure issue above, about how the reduction in Oxygen level makes it harder for us to absorb oxygen out of the air at high altitude.

On a related note, sherpas are genetically different and adapted to functioning at high altitudes. I read about this a few years back and thought that it was fascinating.

https://www.bbc.com/news/science-environment-40006803

This is the finding of a new study that investigated high-altitude adaptation in mountain populations.

The research involved taking muscle samples from mountaineers at 5,300m altitude and even putting them on an exercise bike at Mt Everest Base Camp.

The Sherpas owe this ability to an advantageous genetic mutation that gives them a unique metabolism.

It has long been a puzzle that Sherpas can cope with the low-oxygen atmosphere present high in the Himalayas far better than those visiting the region.

Mountaineers trekking to the area can adapt to the low oxygen by increasing the number of red cells in their blood, increasing its oxygen-carrying capacity.

In contrast, Sherpas actually have thinner blood, with less haemoglobin and a reduced capacity for oxygen (although this does have the advantage that the blood flows more easily and puts less strain on the heart).

"This shows that it's not how much oxygen you've got, it's what you do with it that counts," concludes Cambridge University’s Prof Andrew Murray, the senior author on the new study.

What the biochemical tests on the fresh muscle showed was that the Sherpas' tissue was able to make much better use of oxygen by limiting the amount of body fat burned and maximising the glucose consumption.

"Fat is a great fuel, but the problem is that it's more oxygen hungry than glucose," Prof Murray explained.

In other words, by preferentially burning body sugar rather than body fat, the Sherpas can get more calories per unit of oxygen breathed.

The result impresses Federico Formenti of King’s College, London, whose own trekking study a decade ago, monitoring oxygen consumption through breath sensors, suggested Sherpas can produce 30% more power than lowlanders.

"This paper provides a cellular mechanism for what we found at the whole body level; that Sherpas use less oxygen to do the same job," he says.

James Horscroft agrees the difference in performance is impressive. "It was pretty clear straight away that our tissue experiments were showing different metabolisms for the two groups. In fact, the difference was so astounding we were worried if the tests were working."

But back in Cambridge the results were borne out. And a genetic variation altering the way fats are burned was established, too. While all of the Sherpas carried the glucose-favouring variant of the metabolic gene, almost none of the lowland volunteers did.

Sherpas are a specific population amongst the Nepalese ("the Ferraris of the Himalayans", Formenti calls them) who migrated to the country 500 years ago from Tibet, which has been occupied by humans for at least 6,000 years. That is plenty of time for a beneficial gene to become embedded, Prof Murray argues.

"It's not down to one gene, of course. We see better blood flow through the capillaries; and they appear to have a richer capillary network as well so that the oxygen can be delivered better to the tissues. But this gene would also have given them some advantage."