What is the purpose of the alveoli in the lungs?
a) Production of mucus
b) Gas exchange
c) Filtering blood
d) Pumping air into the bronchi
b) Gas exchange
The alveoli are tiny air sacs in the lungs where oxygen and carbon dioxide are exchanged between the lungs and the blood. This gas exchange is essential for supplying oxygen to the body's cells and removing carbon dioxide from the body.