Your lungs and how they work?

You have two lungs in your chest cavity which sit on either side of your heart. The left lung is smaller than the right because it shares that side of your chest with your heart.
When you breathe in, air enters your airways via your nose and mouth. The air traves into your windpipe, (also called your trachea) which then divides into airways called bronchi. Your right bronchi for your right lung, your left bronchi for your left lung. These branch into smaller and smaller airways. At the end of the tubes are tiny air sacs called alveoli where gas exchange takes place. Under a microscope, the inside of your lungs look like a giant sponge.
Mucus is produced from goblet cells in the walls of the airways which help keep your lungs clean and well lubricated. Unwanted materials stick to the mucus. Mucus is moved by tiny hairs called cilia that line your airways. They move back and forth sweeping the mucus out of your lungs and into your throat. When the mucus reaches the throat, it’s usually swallowed without you realising.
If your mucus builds up or if you have an inflammation, coughing can help to clear it from the airways.
Some people with lung diseases can have increased sputum which can be difficult to clear. Physiotherapy can help by teaching you different airway clearance techniques to clear your sputum.
Adapted from BLF
Here is a presentation about Airway Clearance