Re: Greek plane crash questions

[Jose]

>> The useful consciousness time as it reaches its high-altitude minimum is mostly the transit time of the already oxygenated blood that just left your lungs on the way to the brain at the "moment" of pressure loss--when that low oxygen blood gets there, your conscious brain cells, which have some of the most rapid replenishment rates of any tissue in the body, go to sleep almost immediately.
>
Ok, so why don't I collapse right away after taking a breath of helium
to talk like Donald Duck?

And...btw... this is a perfect example of why I trim newsgroups. I
originally sent this as a "reply", as I was told to do by people here
who have some issue with my trimming groups and/or indicating which ones
I follow.

My newsreader is dumb.

The reply went =only= to alt.disasters.aviation, where I will never see
a reply and will probably be accused of hit and run posting, an
accusation I will also never see. Followups had been set to that group,
and I didn't catch that. I don't follow that group. But discussion
seems to be happening here too.

My newsreader is dumb.

So now I'm replying manually here only, so that if there is a reply,
I'll actually see it.

Jose
p.s. My newsreader is dumb.
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

[Bushleague]

Actually it is referred to as oxygen partial pressure. With time of
usefull conciousness at FL350 less than 90 seconds, the PIC
(whether the pilot flying or not) usually donns his mask first,
switches the mixer box from boom to mask in order to establish
communications, regains control of the aircraft, then instructs the
F/O to do the same.

Part of Rome was built in a day.

Bush

[George Patterson]

Jose wrote:
>
> Ok, so why don't I collapse right away after taking a breath of helium
> to talk like Donald Duck?

Because at anything close to sea level, the oxygen that is already in your
bloodstream stays there. At altitude, it comes out of your bloodstream. At
altitude, none of the blood leaving the lungs contains enough oxygen to do you
any good. When you take a breath of helium, there won't be any transfer of
oxygen into the bloodstream from that breath, but there is still oxygen left in
that portion of the blood from the last time it passed through the lungs.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

[Jose]

> When you take a breath of helium, there won't be any transfer of oxygen into the bloodstream from that breath, but there is still oxygen left in that portion of the blood from the last time it passed through the lungs.

There was an earlier message concerning somebody breathing nitrogen by
accident (I presume at sea level) and going into immediate convulsions.

Why nitrogen and not helium?

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

[George Patterson]

Jose wrote:
>
> There was an earlier message concerning somebody breathing nitrogen by
> accident (I presume at sea level) and going into immediate convulsions.
>
> Why nitrogen and not helium?

Dunno.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

[Stefan]

Jose wrote:

> There was an earlier message concerning somebody breathing nitrogen by
> accident (I presume at sea level) and going into immediate convulsions.

Nobody said immediate.

The point is you can't entirely empty you lungs by just exhaling, the
human body just isn't built for this. So there's still oxygen in the
lungs even when you take one or two breathes of pure helium (or
nitrogen, for that matter). If however you continue to breathe pure
helium, you will loose consisiousness pretty quickly.

If the environmental pressure falls, this is an entirely different
situation.

Stefan

[Dave]

Isn't our atmosphere made up of 70% nitrogen?

"Jose" > wrote in message
...
>> When you take a breath of helium, there won't be any transfer of oxygen
>> into the bloodstream from that breath, but there is still oxygen left in
>> that portion of the blood from the last time it passed through the lungs.
>
> There was an earlier message concerning somebody breathing nitrogen by
> accident (I presume at sea level) and going into immediate convulsions.
>
> Why nitrogen and not helium?
>
> Jose
> --
> Quantum Mechanics is like this: God =does= play dice with the universe,
> except there's no God, and there's no dice. And maybe there's no
> universe.
> for Email, make the obvious change in the address.

[Ron Lee]

"Dave" > wrote:

>Isn't our atmosphere made up of 70% nitrogen?


Closer to 78 %. But why quibble over 8-9%

Ron Lee