Are aircraft wings airtight? Is there any no air proof design for the wings? Or are  some of the parts are equivalent to outside pressure and some have gauge pressures?

Are some parts airtight and others not?
No part of my Cessna Cardinal wings are airtight. Even the fuel tanks are vented to allow air in to replace the fuel this is used.
The area around the flaps, flap motor aileron control cables, etc., none are airtight.