Throughout our life, day after day, we breathe in dust. I think not only of chemical particles caused by fuel combustion, but also microscopic fibers of cotton, wool and synthetic fabrics we breathe in our homes, mineral dust we inhale when driving on dusty roads, tiny particles of rubber from millions of automobile tires.
Are those particles absorbed, eliminated ? It seems impossible that all that foreign matter is being accumulated in our lungs.
IANAD, but capturing and eventually removing that stuff is what mucus is for.
The audible “clunk” of one’s dust-cluttered lungs as they land on the diaphram is the last sound many of us hear.
Quite a bit of the dust and stuff we inhale is eliminated by mucus, lung cillia, and coughing. There is also the involvement of some types of immune-system cells as well.
However, superfine particles may not be, and gradually accumulate. Asbestos is also problematic, and tends to stay in the lungs. So as we age, yes, there’s a certain amount of long-term grit. However, assuming a healthy lifestyle, you’ll die of something else long before your lungs completely solidify. In normal conditions the mucus along your entire respiratory track traps gunk, and coughing/sneezing gets rid of the vast majority of it.
It’s also possible to overwhelm the lung’s clean up crew. Smoke, for instance, can damage the cillia and vastly decrease the lungs’ ability to clear themselves, not to mention at the gunk and superfine particles that tend to stick around (hence the notably abnormal appearance of lungs removed from long-term smokers). Coal mining also generates dust and crap that lodges long-term in the lungs (black lung), as do certain agricultural operations (brown lung), stoneworking, and other industries. Then there are natural phenomena, such as volcanoes, which can generate a very fine “ash” which is really microsopic shard of volcanic glass, very tiny, and complete with razor sharp edges. This stuff is not something you want to breathe in.
So, kids, don’t smoke, use respirators when called for in industry and hobbies, and stay away from erupting volcanos.
Aye, and hence the primary purpose of Leukocytes, a macrophage, or white blood cells. Leukocytes ingest foreign objects through Phagocytosis and neutralize the invading entity and eliminate it, principally, by the expulsion of phlegm, which is mainly WBC’s and associated phagocytotic foreign bodies.
Satisfying answers. Thanks everyone