Coughing serves the cleaning mechanism for the upper airways (roughly up to generation 7 of the bronchi). In other words: the mechanism coughing does not work further down (down in the smaller airways)! Phlegm from further down is delivered by mucociliary clearance. Down at the bottom, a very thin mucus layer, the surfactant, helps to transport it further. When it comes to coughing and secretion, always keep in mind: only cough at the end, when the phlegm has come far enough to the top!
What types of cough are there?
Those who suffer increasingly from sputum and cough will soon notice that there are different kinds of coughs.
Types of Cough
The sputum which is transported up and coughed out can vary in colour and shape. This indicates the state that the airways are in.