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| Module 4: Lung Defences Against The Environment - The Mucous Layer. |
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| Module 4: Lung Defences Against The Environment - The Mucous Layer. |
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Defence against particulates begins with the nasal turbinates and hairs which trap large particles ( > 10 microns). Turbulent flow in smaller airways results in particulates depositing on the muco-ciliary escalator.
As shown in the figure below, the mucous is produced by glands in the respiratory epithelium and comprises of sol (watery) and gel (sticky) layers. Epithelial cilia waft the sol layer and the gel layer with it, towards the larynx.
Dust particles trapped in the mucous are thereby expelled, either being coughed out or swallowed.
At particle size < 7 microns these defences become increasingly less efficient and there is pulmonary retention.
Postgraduate Diploma in Occupational Health (DOH) - Modules 3 – 5: Occupational Medicine & Toxicology by Prof Rodney Ehrlich & Prof Mohamed Jeebhay is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Permissions beyond the scope of this license may be available at http://www.healthedu.uct.ac.za/