Thought you might find this intriguing Old Mike
Researchers discover mechanism for fixing defective mucinswww.sciencedaily.com/releases/2015/10/151002113546.htm
"Proper lubrication is crucial to keep not only machines but also humans functioning smoothly. The mucus membranes in our mouths, eyes, stomachs and genital area help keep friction to a minimum and also protect us against environmental hazards such as chemicals and pathogens. Researchers are investigating exactly how these mechanisms work."