Medical columnist, Mitchell Hecht, wrote an interesting article about " Why the need for phlegm and mucus?"
Excerpts of the article are reproduced below for your convenience:
[Phlegm is just an accumulation of thick mucus secreted by cells that line the nasal and respiratory tracts. It's usually clear/white/yellow in appearance and is spit out with coughing.
Mucus keeps the respiratory and nasal tissue moist and lubricated so it doesn't dry out, and traps small particles of dust and other foreign matter so that they don't enter the tiny air sacs of the lungs (alveoli).
Mucus keeps the respiratory and nasal tissue moist and lubricated so it doesn't dry out, and traps small particles of dust and other foreign matter so that they don't enter the tiny air sacs of the lungs (alveoli).
Along with the mucus, there are millions of tiny hairlike structures called cilia that line our upper respiratory tract. They beat and sweep away allergens, bacteria, and irritants trapped in mucus at a rate of 10-20 times per second in the direction of the mouth. Smoking causes cilia hairs to fall out, which is one reason why smokers get more respiratory infections than nonsmokers.
Normally, mucus is thin and watery, but in certain inflammatory situations like a cold or bronchitis, there's an excess of thick mucus (phlegm). Allergies, sinus infection, or irritants like cigarette smoke are triggers, which may cause an overproduction of mucus and a post- nasal mucus drip.
Chronic lung disease also can be a frustrating cause of phlegm. Postnasal mucus drainage on the back of the throat is very irritating and often causes a sore, scratchy throat by morning. During sleep, saliva production decreases, resulting in less clearing of mucus. When awake, you'll drink liquids to thin the irritating mucus and wash it away; you'll also swallow much more often. That's why you'll notice that your scratchy/sore throat is much better after drinking liquid (hot or cold), and as the day goes on.
Gargling also helps to bathe and rehydrate the irritated tissues. Thinning mucus with guaifenesin (e.g.- Robitussin, Mucinex) makes it easier to cough up and clear. If you're producing abundant phlegm and it's not clearing up, get it checked out by a doctor.]
It is important to be able to distinguish between normal mucus and sinus infection mucus. Learn how to tell the difference between sinus infection symptoms and what remedies are effective for sinus infection treatment.
