It looks gross, it’s a nuisance, but there is no debating the important functions that mucus (better known as “snot” or phlegm) serves for our health.
Mucus is produced by tissue (epithelial, or surface cells) lining the mouth, nose, sinuses, throat, lungs and gastrointestinal tract. Mucus has a number of essential functions; one of them is to protect all those soft and delicate organs it lines, to keep them from getting dry and irritated as a result of our continual breathing. Mucus also serves to attract dust, pollutants in the air that we breathe, as well as bacteria and other foreign particles, before they can enter the body; it’s gooey and sticky, so that it can trap things.
Like all tissues and fluids in our bodies, the chemical composition of mucus is complex. Mucus is 95 percent water, most of which is bound in proteins called mucins, which form a gooey liquid when mixed with fluids. Mucus also has antibodies that help the body recognize invading microbes; and it has enzymes that kill foreign organisms. Tiny hair-like structures called cilia, which line the esophageal and nasal cavities, help push the mucus outward when we sneeze or cough, and the sticky nature of mucus helps insure that foreign particles or bacteria do not enter our lungs when we breathe.
Mucus, then, is something that our bodies make at all times, even when we’re healthy. In fact, the adult human body makes about 1 to 1.5 liters of the stuff every single day! Most of this mucus trickles down quietly down our throats; but when we get sick, its consistency gets thicker, which causes us to notice it and to want to expel it.
When we come down with a bad cold, or when we have an allergic reaction, the body starts producing more mucus. For example, when a person is exposed to something to which they’re allergic, such as pollen, specialized cells release histamine, which causes itchiness and sneezing; mucus membranes start releasing fluid, which causes a runny nose.
You may also notice that you produce more mucus when you drink milk, and that your nose gets watery when you eat spicy foods. This is caused by a little-understood phenomenon called non-allergic gustatory rhinitis, which resembles an allergic reaction but which is normal.
As we know, mucus can have a variety of colors. For example, when we have a cold, our mucus can appear yellowish or green. This is because of white blood cells called neutrophils that the body sends to the affected area, which have a greenish enzyme that in large numbers can make the mucus appear green.
Decongestants should be used with caution, if at all, during a cold or allergies. This is because overuse of them can cause the nasal cavities to produce thicker mucus and thus drain less effectively, which can increase the risk of infection. In addition, when you decrease the amount of mucus that the body is trying to eliminate, you are also restricting an important route for pathogens and allergens to be removed from your system.
Why Do We Get Runny Noses in Cold Weather?
This is because the cilia that normally push mucus from our nose to the back of the throat become less active or completely inactive in cold weather. That causes the mucus to run down and out the nose. Mucus also thickens in cold weather, so that when you come in from the cold, it thaws before the cilia start to work again, causing your nose to drip.
By Marc Courtiol