DSLR air leakage

I presume (and this may be a dumb thing to say) that air enters and leaves the camera through the lens/camera interface. Although the camera is "sealed" I presume that water and air can move through the gap between the metal surfaces of the lens and camera interface. (there are no rubber seals or are there?)
So air pressure can equalize etc. It also means though that dust and moisture can get into the camera to some limited extent.
Also when a zoom lens changes length etc there must presumably be air movement in and out of the lens, although not through the camera body, so dust and moisture can get into the lens also to a limited extent.
Anyone know if this is true?
Not that we can do anything about it except keep our gear clean of course.

Air certainly gets in, especially in the zooms.... I learned the hardway when my 55-200mm VR rolled into a pond and I pulled it out and saw lots of water droplets on the INSIDE. I had the cap on the back so the electronics were all sealed, but the water got in where the zoom mechanism connects I guess.

(The lens was saved via my oven and some rice, though the inside of the glass was a little dirty)

Bill - For some of the pro setups, both lenses and camera body are sealed, including a gasket that seals at the lens mount. They probably aren't airtight, but are largely water-tight. And zooms that physically extend would let in a lot more air/water than zooms that are fixed physical length I'd assume.

A friend dropped his camera into water and Nikon fixed it... for $350!

That is one of the advantages of the internal focussing (IF) lenses I believe. Since the design doesn't use the two external barrels to focus there is no change in the internal pressure. Feel free to let me know if I am wrong on this though.....