Alveoli.
Capillaries . The smallest of the blood vessels: capillaries.
the air goes into your lungs. In your lungs there are billions of tiny air sacs. Surrounding each air sac is a network of blood capillaries. The air sacs and the blood capillaries are separated by a thin membrane. Across this membrane the air sacs give the blood capillaries oxygen and they blood capillaries give the air sacs carbon dioxide. We breathe out this carbon dioxide!
capillaries
These are called alveoli. The singular term is alveolus.
alveoli
They are called Alveoli, look that up on wikipedia, or in your textbook.
Another name for ARDS is shock lung. Its formal name is misleading, because children, as well as adults, may be affected. In the lungs the smallest blood vessels, or capillaries, make contact with the alveoli, tiny air sacs.
Consisting of thousands of tiny air sacs increases the surface area inside of the lung which allows for better gas exchange. If the lung was made of one larger air sac, you would not be able to exchange as many gases (oxygen/CO2) with each breath.
The Alveoli are the tiny sacs and they are located through out the whole lung.
The smallest tube in the lungs is the Bronchus
lungs