Top marks in school go to Mr Flexpwr...
To add a little more; think of pressurisation like blowing up a childs balloon;
to get the same in our aeroplane we first bung up all the leaky holes (I know some aeroplanes leak more than others eh?); then to make sure our balloon doesn't doesn't burst; we regulate a leak (using what are called 'Outflow valves'), allowing the air that has come from the air conditioning
packs, to escape once it has done its' job of warming or cooling down
everyone inside.
ttfn