Mucus (shown in pink) is secreted by a cell in the stomach. (Credit: The Path to Digestion Is Paved with Repair. Underwood J, PLoS Biology Vol. 4/9/2006, e307. doi:10.1371/journal.pbio.0040307)

We know it best as a stringy slime dripping from noses and as viscous, discolored goop hacked up by sickened airways. But it’s so much more than that. Coating the surfaces of guts, eyes, mouth, nasal cavity and ears, mucus plays a range of important physiological roles — hydrating, cleaning, supportin