Life Without These Body Fluids Is Impossible

Mucus
Mucus sounds unpleasant, but none of us would be here without it. A slippery, clear liquid produced by mucous glands, it lines the cells of the bronchi in the lungs, the stomach and intestines, the urinary and reproductive tracts, and the eyes and ears. Mucus contains a variety of important substances, including antiseptic enzymes, antibodies and mucins that give mucus its gel-like properties. The average adult produces about one liter of mucus per day. Mucus keeps the lining of the respiratory system from drying out and also filters out dust and infectious agents in the air we breathe. Microscopic hair-like projections from the cells lining the lung’s air passages help to propel the mucus back up toward the mouth at a speed of about one millimeter per minute, where it can be swallowed or expectorated. Patients with cystic fibrosis have a genetic mutation that makes their mucus too thick, undermining this important defense against infection.