Lung mucus: A clinician′s view

In ancient times, respiration's perceived purpose was only to cool the blood, and nasal mucus was thought to be a discharge from the brain. Later it was demonstrated that fluids cannot travel from the brain to the nose. It appears that credit for pointing out the medical significance of bronchial secretions and the biological value of the exocrine function of the lungs belongs to Laennec. He described the “chronic idiopathic pituitous catarrh” known today as bronchorrhea, which is characterized by paroxysms of expectoration. The importance of all this is that airway secretions, and their alterations, became one of the cardinal signs of many respiratory diseases (1).