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The trachea (pl.: tracheae or tracheas), also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all animals lungs. The trachea extends from the larynx and branches into the two primary bronchi.
Mammals also have motile cilia or secondary cilia that are usually present on a cell's surface in large numbers (multiciliate), and beat in coordinated metachronal waves. [40] Multiciliated cells are found lining the respiratory tract where they function in mucociliary clearance sweeping mucus containing debris away from the lungs . [ 13 ]
The cells in the respiratory epithelium are of five main types: a) ciliated cells, b) goblet cells, c) brush cells, d) airway basal cells, and e) small granule cells (NDES) [6] Goblet cells become increasingly fewer further down the respiratory tree until they are absent in the terminal bronchioles; club cells take over their role to some extent here. [7]
The trachea is the largest tube in the respiratory tract and consists of tracheal rings of hyaline cartilage. It branches off into two bronchial tubes, a left and a right main bronchus . The bronchi branch off into smaller sections inside the lungs, called bronchioles .
Cilia movement in a metachronal wave. The coordinated movement of the cilia on all the cells is carried out in a fashion that is not clear. This produces wave-like motions that in the trachea, move at a speed of between 6 and 20 mm per minute. [2] The wave produced is a metachronal wave that moves the mucus. [5]
Pseudostratified epithelia function in secretion or absorption. If a specimen looks stratified but has cilia, then it is a pseudostratified ciliated epithelium, since stratified epithelia do not have cilia. Ciliated epithelia are more common and lines the trachea, bronchi.
The bronchi and non-cartilaginous portions of the trachea collapse to form slits through which the air is forced, which clears out any irritants attached to the respiratory lining. Stimulation of the auricular branch of the vagus nerve supplying the ear may also elicit a cough.
All of the lower respiratory tract including the trachea, bronchi, and bronchioles is lined with respiratory epithelium. This is a ciliated epithelium interspersed with goblet cells which produce mucin the main component of mucus , ciliated cells, basal cells , and in the terminal bronchioles – club cells with actions similar to basal cells ...