... or at least i think it falls under chemistry. what is the scientific term for the continuous even dispersion of oxygen in the air? say, so that we don't have to inhale from another direction once we exhale in one?
Homogeneous (chemistry) - Wikipedia, the free encyclopedia http://en.wikipedia.org/w/index.php?title=Dispersion_(chemistry)&oldid=382899226 [ame="http://en.wikipedia.org/wiki/Mixture"]Mixture - Wikipedia, the free encyclopedia[/ame]
biology is chemistry. chemistry is physics. physics is math. eventually you give up on what to call it.
You can inhale and exhale in the same direction because the body doesn't actually use all that much oxygen, combined with the effects of diffusion and convective mixing mentioned above. Exhale still contains ~16% oxygen, which is why you can give mouth-to-mouth, or breathe into a bag for some time before feeling ill. If you inhale an atmosphere with very low oxygen (<5% or so), you'll pass out in seconds. This is seen in industrial accidents where workers enter a vessel full of nitrogen.
And for those who don't know... the general atmosphere is made up of approximately 21% oxygen So each breath uses about 25% of the oxygen available in that breath.
