Mucus, snot, bogeys. Call it what you like, mucus is something we all have. While the slimey, gooey stuff can be unpleasant to think about, we'd really notice if it wasn’t there.
So while it can be gross to blow mucus into tissue after tissue during a cold or sinus infection, remember, mucus actually serves a very important purpose in your nose and beyond.
To delve into the world of mucus, we turned to Jonathan Hern, consultant ear nose and throat (ENT) surgeon at Frimley Park Hospital, Camberley, Surrey, and member of ENT UK.
"Mucus is produced in the nose and sinuses and it's moved in predefined pathways from your sinuses through to your nose and then from your nose to your throat. Then it's swallowed," he says. "So there's a continuous carpet of mucus that's produced. It keeps your nose and throat moist. It helps in humidification of air we breathe through the nose. Air all around us is quite dry, so when we breathe it in to the lungs it's saturated with water mainly as a result of nasal mucus."
Mr Hern says the world of mucus is even more fascinating under the microscope: "You have to look at the microscopic structure of the lining of your nose and sinuses. There are cells which produce mucus: mucus cells or goblet cells. Adjacent - and in higher quantities - there are cells that have things called cilia on the end, like little hairs that beat in a coordinated fashion."
We may not even notice mucus is there until a cold comes on. "If you've got a cold, you produce too much mucus," Mr Hern says. "You can actually feel it in your nose and throat. It occupies volume there."
Extra mucus is part of the body's natural response to a cold. "It's all part of an acute inflammatory response. You get more blood going to the nose and sinuses and more mucus to try and act as a protective mechanism to try to get rid of the viral infection.
"However, in itself, it causes some of the symptoms of a cold. The sinus drainage pathways are quite narrow and convoluted. So if you get too much produced, it tends to get stuck in the sinuses. That's why you feel completely bunged up when you've got a cold. You're not effectively clearing the mucus as you should and it’s building-up in your sinuses and clogging things up."
Mucus production factory
"People often under estimate how much nasal and sinus mucus we produce. It's probably about half a litre a day. It's quite a significant amount," Mr Hern says. Plus we make even more when we have a cold. "You can produce very much more."
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