system
Given the following post, respond as if you're commenting on Reddit:
human
How does the cabin in an airplane pressurize and maintain that pressure? Where does the oxygen come from as well?
gpt
Air from the compressor stage of the engine is diverted through a heat exchanger and introduded into the cabin.  Outflow valves modulate to control the pressure according to a computer profile.  Its just regular air with the same concentration of oxygen/nitrogen, etc.  Its just too low of pressure to get absorbed by your blood.  Get it close to sea level pressure and your body can use it.

Im an airline pilot.