Phlegm

Phlegm, and mucus as a whole, is in essence a water-based gel consisting of glycoproteins, immunoglobulins, lipids and other substances.

[1] The body naturally produces about 1 quart (about 1 litre) of phlegm every day to capture and clear substances in the air and bacteria from the nose and throat.

Mucus is a normal protective layering around the airway, eye, nasal turbinate, and urogenital tract.

Mucus is an adhesive viscoelastic gel produced in the airway by submucosal glands and goblet cells and is principally water.

Phlegm naturally drains down into the back of the throat and can be swallowed without imposing health risks.

Once this is done, a U-shape should be formed with the tongue, while simultaneously forcing air and saliva forward with the muscles at the back of the throat.

In his 1889 farewell speech at the University of Pennsylvania, Sir William Osler discussed the imperturbability required of physicians.

"'Imperturbability means coolness and presence of mind under all circumstances, calmness amid storm, clearness of judgment in moments of grave peril, immobility, impassiveness, or, to use an old and expressive word, phlegm.

Nobel laureate Charles Richet MD, when describing humorism's "phlegm or pituitary secretion" in 1910 asked rhetorically, "this strange liquid, which is the cause of tumours, of chlorosis, of rheumatism, and cacochymia - where is it?