Your respiratory system starts at at your nostrils and mouth, where oxygen goes in. It then passes into the pharynx and trachea and then into the right and left bronchi, which branch into smaller bronchioles, and finally into the millions of tiny alveoli. Actual gas exchange takes place in the alveoli.
A microchip is millions of electronic components placed on a tiny piece of silicon.
alveoli
the aveoli
Cilia are the tiny hairs that sweep dust and dirt out of the respiratory system.
flea?
alveoli
The alveoli in the lungs.
Your question is unclear. Are you asking what does the most in the respiratory system , then tiny little sacs called the alveoli do.
The tiny lines at the end of characters in some fonts
post office
oil