system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: How are lungs self-cleaning?

Edit: More specifically, how does the cleaning occur? Is it simply the constant pumping of air in and out of the lungs? Or is it through other means?
gpt
You’ve got a sticky substance called mucus in your airways that catches the bad stuff. This sticky substance and the bad stuff are then moved up the airway by the action of these hair-like things on the outside of the cells called cilia. The cilia beat back and forth to move all that stuff like a conveyor belt up the airway so you can cough it up and out of your body. 

This is called mucociliary clearance.


Edit to add: some diseases which affect this process include cystic fibrosis in which the mucus is thicker and so it doesn’t move up the airway as well. Since it gets stuck and doesn’t move out as easily you’re more prone to get sick because the mucus is trapped. Another example of a disease is ciliary dyskinesia where the cilia don’t work well so the mucus isn’t able to move up and coughed out, also making you more prone to getting sick.