Mucus: It's snot what you think

To many people, mucus is nothing more than a gross goo, something to be tossed away in a tissue immediately after clearing your throat or blowing your nose.

To scientists, it is nothing short of a medical marvel - an unsung hero in keeping people healthy and a potential gold mine for new treatments.

"It's really this masterpiece of biological engineering in my mind," said Massachusetts Institute of Technology professor of biological engineering Katharina Ribbeck, whose laboratory is dedicated to the study of mucus.

The sticky substance is essential to many of the body's functions. It can help people swallow and digest food, disarm harmful bacteria and even help build a healthy microbiome.

"Mucus has got a bad rap," said Dr Richard Boucher, a pulmonologist and director of the Marsico Lung Institute/UNC Cystic Fibrosis Center at the University of North Carolina at Chapel Hill. "People think it's something you should spit out and get rid of, but it's an amazing substance."

IT IS NOT JUST IN YOUR NOSE - IT IS EVERYWHERE More than 95 per cent water by weight, mucus lines all the wet surfaces inside the body - not just the nose, but also the eyes, ears, throat, airways, lungs, gut and urogenital tract.

Its key building blocks are mucins, which are long proteins decorated with complex sugars that make them look like bottle-brushes.

These sugars help attract water, Dr Boucher said, and the mucins form a gel-like mesh that can cover a large surface area like the nasal cavity, keeping it wet while also controlling the passage of pollutants, bacteria, viruses and drugs through it.

"It's designed to protect you from the outside world," Dr Boucher said.