SLIDEBOX - Respiratory System

SUPPLEMENTARY:
Electron micrograph of cilia (LS)

This electron micrograph shows longitudinal sections of the closely packed cilia on the luminal surface of a columnar cell of the respiratory epithelium. Cilia are actively motile and their movements are responsible for transporting the carpet of mucus, produced by the goblet cells and other glands, upwards towards the larynx where the mucus is swallowed.

Factors which affect ciliary activity

Since the activity of cilia is vital for the transport and removal of mucus from the deeper parts of the respiratory system, any paralysis or impairment of their activity will lead to a build up of mucus within the lungs. Accumulation of mucus is associated with respiratory tract infection.
Some examples of factors which affect the motility of cilia are listed below:

the respiratory system is lined by a delicate pseudostratified epithelium. However, some parts of the tract, which are normally exposed to direct air flow or physical abrasion have a more robust stratified squamous epithelium e.g. epiglottis, vocal folds. If air flow patterns alter e.g. with a chronic cough, the normal ciliated epithelium is lost and replaced by the more resistant stratified epithelium. This is a reversible change referred to as metaplasia. Look at the slide of metaplasia in this tutorial. Any loss of the ciliated epithelium will impair the transport of mucus and cause congestion of the airway
smoking increases levels of noxious gases (CO, SO₂) which causes a reduction in the number of ciliated cells. Loss of ciliary action results in reduced transport of the mucous carpet
cigarette smoke is also known to paralyse cilia
cold dry air
anaesthetics
i-v barbiturate
old age

Tutorial Navigator:

Core	Supplementary Material on Respiratory Epithelium
Return to Core	specialisations of respiratory epithelium	goblet cells & cilia	cilia
	EM of cilia (TS)	pathological increase in goblet cells	metaplasia of the respiratory epithelium
Return to Respiratory System Main Index