To increase surface area for gas exchange.
I belive it's a mixture of cartilage and lung tissue containing cila.
Sponges have folded body walls with holes leading to the inside of the animal. The advantage is that water stays in one area allowing the animal to respire.
A bronchiole has no cartilage in its wall, a bronchus does.
A folded napkin is often folded into a right triangle. The corners of walls can be shaped like a right angle.
Bronchiole is the medical term meaning small bronchi
The parts are the Trachea,Bronchiole,Bronchiole Tubes, Bronchi, and the air sacs.
A folded plate structure is a type of building structure. In this type of structure, there are thin walls and flat plates or components connected to create a dihedral angled shell.
Bronchiole walls are lined with a layer of cells but are not necessarily considered slippery. The lining may have some degree of moisture to aid in the movement of air, but it is not a membrane designed to be slippery.
Alveoli.
hole, mole,
A air sac
the cateye