Hair anatomy

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. 

Quiros, C.F. et al.. Resistance in tomato to the pink form of the potato aphid Macrosiphum euphorbiae. The role of anatomy, epidermal hairs and foliage composition, J. Am. Soc. Hortic. Sci., 102, 166, 1977. 

Jones, L. N. (2001). Hair structure anatomy and comparative anatomy. Clinics Dermatol. 19, 95-103. 

The normal external auditory canal has several mechanisms that protect if from infections. The S-shaped anatomy of the external auditory canal provides protection from foreign bodies under normal circumstances. The tragus provides protection anteriorly, and hair from follicles found just inside the meatus prevent airborne debris from entering. 

An additional variable that must be accounted for in derma absorption studies that may overshadow the difference between chemicals Is body site differences in absorption within a species. Regional variation in skin permeability at different body. sites may be related to skin thickne.ss, number of cell layers, cell size of the epidermis and stratum comeum, and di.stribution of hair follicles and sweat pores. Because of thick layers of stratum corneum, permeability in palmar and plantar skin is expected to be less than that in the scalp or forearm (Feldmann and Maibach, 1974). Data from several studies suggc.st that regional variation in vascular anatomy and blood flow should also be considered (Montciro-Rivicrc o/.. 1990 Qiao cf a/.. 1993). 

Eyelashes are also important to adornment. Eyelashes protect the eyes from sunlight and foreign objects, and they assist in communication. Nasal hairs filter inspired air and retard the flow of air into the respiratory system, thus allowing air to be warmed or cooled as it enters the body. Hair on other parts of the anatomy serves related functions. In addition, a general function of all hairs is as sensory receptors because all hairs are supplied with sensory nerve endings. The sensory receptor function can enhance hair in its protective actions. 

Czamota, M.A. et al. (2003) Anatomy of sorgo-leone-secreting root hairs of Sorghum species. Internat. J. Plant. Sci. 164, 861-866... 

Cobelli, C., 9 5-9-6,9-8-9-9 COCB (crossed olivocochlear bundle), 5-11 Cochlea, 5-1,5-4,5-6 Cochlear amplifier, 5-4 Cochlear implant, 29-6-29-7 Cochlear mechanics, 63-1-63-12 active models of, 63-11-63-12 active process in, 63-9-63-11 anatomy, 63-2-63-4 components, 63-2-63-3 fluid streaming in, 63-12 hair cell gating channels, in cochlear mechanics, 63-10-63-11... 

As we have seen from the discussion of toxicokinetics, the anatomy and physiology of an organism play key roles in defining the toxicity of a chemical to that organism. Birds have feathers rather than hair this impacts absorption. Aquatic mammals like muskrats have an insulating layer of fur that prevents water from reaching the skin. This will also affect absorption. Cattle have four stomachs and have a large... 

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