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Principles of Humidification |   |
Sources of Mucus
Mucus generally comes from two sources: secretion from goblet cells and bronchial (mucous) glands. The goblet cells, which are distributed throughout the epithelium of the mucosa, synthesize and secrete mucus into the airway. The mucous glands, which are in the submucosa, are the greater source of mucus. Chronic irritation or disease can cause the number and size of goblet cells and mucous glands to increase, resulting in a larger and more viscous mucous blanket.
Effects of Mucous Layer
Ciliary activity, which moves the mucus, can be adversely affected if the mucous layer is changed. Changes in the ratio of gel to sol layer will affect the flow of mucus. A higher ratio, due either to a decrease in the watery sol layer or an increase in the viscous gel layer, could make the work load of the cilia too difficult to be effective. The cilia are capable of continuing to beat even if the workload increases, but only to a certain level. If the cilia become tangled in the thick mucus or are unable to penetrate the dense layer, the transport of the mucous blanket would stop, causing secretions to become retained in the respiratory tract.
Increases in the amount of watery sol fluid would also decrease the transport of mucus. The cilia must be able to extend through the sol layer to the gel layer to transport the mucus. Transport would be impaired if the thickness of the sol layer were to eliminate ciliary contact with the gel layer.
Other factors that can impede ciliary activity and the flow of mucus include:
- tobacco smoke
- local environmental conditions
- and pathology of the airway can impede clearance due to changes in the epithelium.