A question about breathing.

[Bushmaster]

You know questions that have bugged you on and off for years, but just not enough for you to make an effort to find the answer? Here's one of mine:

Breathing. In, out. In, out.

What percentage of the oxygen in a lungful is used up on each breath? I mean, of the gases exhaled, what percentage is oxygen compared to the gasses inhaled?

Please tell me.

Thank you.

Edited by Bushmaster on Wednesday 13th August 15:42

[swiftpete]

The air we inhale is roughly 78% by volume nitrogen, 21% oxygen, 0.96% argon and 0.04% carbon dioxide, helium, water, and other gases.

The permanent gases in gas we exhale are roughly 4% to 5% carbon dioxide and 4% to 5% less oxygen than was inhaled.





Took about 15 seconds to find this out through google. You should have looked there years ago!

Edited by swiftpete on Wednesday 13th August 15:36

[roboxm3]

IIRC not that much; below 50%





:runs of to google and wiki:



OK a lot more than 50%

Edited by roboxm3 on Wednesday 13th August 15:38

[captainzep]

Has a lot to do with the efficiency of your cardio-vascular system in terms of individual difference.

Hence VO2max is used as a measure of fitness. The fitter you are, the better adapted you are to utilise the oxygen you inhale. Google VO2max for the science.

[ewenm]

Which is why you can share air underwater for a bit - there's enough oxygen in what you exhale for someone else to use for a breath.

[Mattt]

ewenm said:

Which is why you can share air underwater for a bit - there's enough oxygen in what you exhale for someone else to use for a breath.

That's how rebreathers work.

The breathing reflex is triggered by CO2 buildup in the lungs, hence when you hyperventilate and flush the CO2 from the lungs - then hold your breath, your O2 levels can fall before you are triggered to breathe - and pass out before you know it. IIRC that is.

[Bushmaster]

So if I hold a breath twice as long I will get twice as much oxygen from it. So slow breathing is more efficient than fast breathing? So why do we breath faster when we need more oxygen then, hey? Hey?

[wainy]

Did you know you alternate which nostril you breathe in and out of. Cant remember where I heard that but it is interesting...

[Mattt]

roboxm3 said:

IIRC not that much; below 50%





:runs of to google and wiki:



OK a lot more than 50%

Not really, it goes from c. 20% to c. 16% - so 20% of the original O2 amount by volume.

[ewenm]

Bushmaster said:

So if I hold a breath twice as long I will get twice as much oxygen from it. So slow breathing is more efficient than fast breathing? So why do we breath faster when we need more oxygen then, hey? Hey?

Much bigger volume by breathing more, not less

[Mattt]

Are the lungs more efficient at removing O2 from larger volumes? i.e. the lungs are more efficient removing the first 4% than subsequent amounts, or does it make no difference?

[captainzep]

Mattt said:

ewenm said:

Which is why you can share air underwater for a bit - there's enough oxygen in what you exhale for someone else to use for a breath.

That's how rebreathers work.

The breathing reflex is triggered by CO2 buildup in the lungs, hence when you hyperventilate and flush the CO2 from the lungs - then hold your breath, your O2 levels can fall before you are triggered to breathe - and pass out before you know it. IIRC that is.

Spot on, same concept of people breathing into a paper bag during hyper-ventilation.

[Bushmaster]

And I'll share another one:

Where are all the old men with small ears? Do they die before their African-elephant-gene-sharing brethren? Where are they??

[Bushmaster]

Mattt said:

Are the lungs more efficient at removing O2 from larger volumes? i.e. the lungs are more efficient removing the first 4% than subsequent amounts, or does it make no difference?

Surely drawing that second lungful demands more energy than maximising the usage of the first lungful?

[ewenm]

Bushmaster said:

And I'll share another one:

Where are all the old men with small ears? Do they die before their African-elephant-gene-sharing brethren? Where are they??

Oh oh pick me pick me! Ears don't stop growing throughout your life.

[fadeaway]

ewenm said:

Which is why you can share air underwater for a bit - there's enough oxygen in what you exhale for someone else to use for a breath.

It's also why mouth to mouth resusitation works

[Bushmaster]

ewenm said:

Bushmaster said:

And I'll share another one:

Where are all the old men with small ears? Do they die before their African-elephant-gene-sharing brethren? Where are they??

Oh oh pick me pick me! Ears don't stop growing throughout your life.

You sure? You don't say, what age do you think she is? Don't know, let's have a look at her ears..ah, obviously 39 - look at those lobes! People don't get ear-jobs to make them look younger.

[Bushmaster]

fadeaway said:

ewenm said:

Which is why you can share air underwater for a bit - there's enough oxygen in what you exhale for someone else to use for a breath.

It's also why mouth to mouth resusitation works

Interesting, so a fat unfit person gives you mouth to mouth you should be OK, but if an Olympic athlete does the same you're fked.

[ewenm]

Bushmaster said:

ewenm said:

Bushmaster said:

And I'll share another one:

Where are all the old men with small ears? Do they die before their African-elephant-gene-sharing brethren? Where are they??

Oh oh pick me pick me! Ears don't stop growing throughout your life.

You sure? You don't say, what age do you think she is? Don't know, let's have a look at her ears..ah, obviously 39 - look at those lobes! People don't get ear-jobs to make them look younger.

Blokes only (noses too). Birds do stop.

[fadeaway]

Bushmaster said:

Mattt said:

Are the lungs more efficient at removing O2 from larger volumes? i.e. the lungs are more efficient removing the first 4% than subsequent amounts, or does it make no difference?

Surely drawing that second lungful demands more energy than maximising the usage of the first lungful?

That's not really how the lungs work. They don't "suck" O2 from the air you breath in, rather they allow blood which has already passed around the body to flow past the air that you're breathed in. So what's happening is gas exchange - ie (using approx figures) the blood has 4% CO2, 16% 02 and 80% N, the air you breath in has 0% CO2, 20% O2 and 80% N. So it's just the gasses trying to balance themselves out.