Mucus / Phlegm / Nasal Discharge

Respiratory tracts of animals, including humans (nasal cavity, lungs)

N/A (Not a living organism)

Produced by mucous membranes; traps dust, pollen, and pathogens; expelled via coughing or blowing the nose.

Benefit: Essential for immune defense and keeping airways moist. Risk: Excess production can indicate infection (cold, flu, sinus infection) or allergies.