Epithelia, ciliated

Stratified squamous to mucociliated epithelium with olfactory cells Mucociliated epithelium (ciliated, mucous cells, basal cells) smooth muscle cells fibroblasts neuroendocrine cells immune cells Mucociliated epithelium with Clara cells in distal bronchioles and alveolar ducts... 

Airway cross-sections have the nominal anatomy shown in Fig. 5.16. Airway surface liquid (AST), primarily composed of mucus gel and water, surrounds the airway lumen with a thickness thought to vary from 5 to 10 mm. AST lies on the apical surface of airway epithelial cells (mostly columnar ciliated epithelium). This layer of cells, roughly two to three cells thick in proximal airways and eventually thinning to a single cell thickness in distal airways, rests along a basement membrane on its basal surface. Connective tissue (collagen fibers, basement membranes, elastin, and water) lies between the basement membrane and airway smooth muscle. Edema occurs when the volume of water within the connective tissue increases considerably. Interspersed within the smooth muscle are respiratory supply vessels (capillaries, arteriovenous anastomoses), nerves, and lymphatic vessels. 

Hansen A., Zeiske E. and Reutter K. (1994). Microvillous and ciliated receptor cells in the olfactory epithelium of the Australian Lungfish, Neoceratodus forsteri. In Advances in Biosciences 93 (Apfelbach R., et al., eds.). Elsevier, Oxford, pp. 43-51. 

Local host defenses of both the upper and lower respiratory tract, along with the anatomy of the airways, are important in preventing infection. Upper respiratory defenses include the mucodliary apparatus of the nasopharynx, nasal hair, normal bacterial flora, IgA antibodies, and complement. Local host defenses of the lower respiratory tract include cough, mucodliary apparatus of the trachea and bronchi, antibodies (IgA, IgM, and IgG), complement, and alveolar macrophages. Mucus lines the cells of the respiratory tract, forming a protective barrier for the cells. This minimizes the ability of organisms to attach to the cells and initiate the infectious process. The squamous epithelial cells of the upper respiratory tract are not ciliated, but those of the columnar epithelium of the lower tract are. The cilia beat in a uniform fashion upward, moving particles up and out of the lower respiratory tract. 

Herzog and Pletscher (1955) observed squamous metaplasia of the ciliated bronchial epithelium in two patients exposed to undetermined concentrations of phosgene. The metaplasia was observed 3 mo or 3 y postexposure, respectively. 

The highly vascularized respiratory epithelium is composed of five major cell types ciliated cells, nonciliated cells, columnar cells, goblet cells, and basal cells. Low numbers of neurosecretory cells are present in the basement membrane [17]. Approximately 20% of the total number of cells in the lower turbinate area is ciliated with fine projections ( 100 per cell) on the apical cell surface. Cilia are used to transport the mucus toward the nasopharynx. These long (4-6 fxm) and thin projections are mobile and beat with a frequency of 1,000 strokes per min. Ciliated and nonciliated columnar cells are populated with about 300 microvilli per cell, which help in enlarging the surface area. 

Figure 10.1 Typical tracheo-bronchial and bronchiolar epithelia showing the major cell types. The tracheo-bronchial epithelium showing the pseudostratified nature of the columnar epithelium, principally composed of ciliated cells (C), interspersed with goblet cells (G), brush cells (Br), serous cells (S), Kulchitsky s cells (K) and basal cells (B). The bronchiolar epithelium showing the cuboidal nature of the epithelium, principally composed of ciliated cells (C), Clara cells (Cl) and infrequent basal cells. Muc = mucus Ci = cilia N = nucleus Sec = secretory granules.

Iravani, J. Clearance function of the respiratory ciliated epithelium in normal and brochhic rats, pp. 143-148. In W. H. Walton, Ed. Inhaled Particles III. Vol. 1. Proceedings of an International Symposium organized by the British Occupational Hygiene Society. 1970. Surrey Unwin Brothers Limited. 1970. 

The oviducts are also known as the Fallopian tubes or uterine tubes. The wall of the oviduct consists of three layers a mucosa, a muscular layer and an outer layer of connective tissue. When the ovum is released by the ovary, it is taken up by the oviduct. The ends of the oviducts are not directly attached to the ovaries but open into the abdominal cavity close to them. The opening of each is funnel-shaped and surrounded by long finger-like projections, fimbriae, with ciliated epithelium which catch the ovum as it is released. The other ends open directly into the uteras. The lower end of the latter is known as the cervix and opens into the vagina. 

Dust particles inhaled in tobacco smoke, together with bronchial mucus, must be removed from the airways by the ciliated epithelium. Ciliary activity, however, is depressed by tobacco smoke mucociliary transport is impaired. This depression favors bacterial infection and contributes to the chronic bronchitis associated with regular smoking. Chronic injury to the bronchial mucosa could be an important causative factor in increasing the risk in smokers of death from bronchial carcinoma. 

The nasopharynx begins with the anterior nares and extends down to the larynx. The nasal passages are lined with vascular mucous epithelium composed of ciliated epithelium and scattered mucous glands. The nasopharynx filters out large inhaled particles and is where the relative humidity is increased and the temperature of the air is moderated. 

Particles deposited on or in the lung parenchyma are cleared primarily by alveolar macrophages. These phagocytized particles migrate to the ciliated epithelium or to the... 

The nasopharyngeal canal is lined by ciliated epithelium through which mucous glands are scattered. The role of this region is to remove large inhaled particles and to increase the humidity and temperature of inhaled air. 

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