Physiotherapy Question:

You breathe with the help of your diaphragm and other
muscles in your chest and abdomen. These muscles literally
change the space and pressure inside your body to
accomodate breathing. When your diaphragm pulls down, it
not only leaves more space for the lungs to expand but also
lowers the internal air pressure. Outside, where the air
pressure is greater, you suck in air in an inhale. The air
then expands your lungs like a pair of balloons. When your
diaphragm relaxes, the cavity inside your body gets smaller
again. Your muscles squeeze your rib cage and your lungs
begin to collapse as the air is pushed up and out your body
in an exhale.