Biology

Unexplained phenomenon of Biology:

There is one thing I need don't understand in Biology but would like to. I came across it when studying... *sure*.

Respiration:

Do the Alvioli (air sacks) just hang around in the lungs or are they lining the walls of the lungs or do they make up the walls of the lungs? If one of the latter two, then how could the expansion of the lungs change pressure in your bronchi, trachea etc.

If you can answer this question... you can follow my blog! So hurry up! Limited time on offer!