Mucus, though it may bring up feelings of disgust, is actually a remarkable and wonderful substance. It is one of the many tools available to your body when infections try to creep in and it’s the same substance that snails and slugs produce in order to help them move about.
Most of the time, you are completely oblivious to the presence of mucus in your body. Indeed, you manage to produce about a litre of the stuff each day and you only really notice when it starts dripping out of your nose. One of its main purposes is to function as a filtration system, with its stickiness helping it to catch dust and other irritants before they damage your respiratory system, as well as fungi, bacteria and viruses before they have a chance to multiply and harm your body. This mucus is continually moving down your throat and the foreign substances can be expelled through your digestion system.
If the volume of irritant is quite large, however, as is often the case with allergens, then your body may trigger a cough or a sneeze in order to expel the mucus and the irritant along with it. The reason why smokers cough is because the increase in pollutants causes the body to produce more mucus. This mucus must then be gotten rid of, so coughing is triggered as a way of expelling this excess.
Mucus also plays a vital role in ensuring that the delicate tissues that line your nasal cavity and airways from drying out. The painful sensation that you sometimes get in your nose and throat can often be down to problems with mucus production. Without mucus, these tissues dry out and become much more sensitive to the particles that pass through your nose and mouth.
The blocked nose feeling that you get during a cold is not related to the mucus in your nose, though it certainly feels that way when you start sniffling. Instead, what you are feeling is the swollen blood vessels in your nasal cavity that are restricting air flow. The blood vessels need to expand in order to accommodate the influx of white blood cells to the area. As an interesting side note, have you ever noticed that you only breathe through one nostril at a time anyway? It’s known as the nasal cycle and you only really become aware of it when you’re feeling blocked up.