ASK DR. H: How the respiratory system stays moist

BY DR. MITCHELL HECHT

Q: Can you tell me why we need phlegm or mucus? It’s just an annoyance. —- B.R., Huntsville, Ala.

A: Phlegm is an accumulation of thick mucus secreted by cells that line the nasal and respiratory tracts. It’s usually clear/white/yellow in appearance and “expectorated” (i.e. spit out) with coughing. Mucus is a pretty important secretion. It 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. 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 (i.e. phlegm). Allergies, sinus infection or irritants such as cigarette smoke are triggers, which may cause an overproduction of mucus.

Chronic lung disease also can be a frustrating cause of phlegm. Post-nasal 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) 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.

Dr. Mitchell Hecht is a physician specializing in internal medicine. Send questions to him at: “Ask Dr. H,” P.O. Box 767787, Roswell, GA30076. Because of the large volume of mail received, personal replies are not possible.