| OHC | occupational health center; outer hair cell |
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| REEDS | retention of tears, ectrodactyly, ectodermal dysplasia, and strange hair, skin and teeth [syndrome] |
| woolly hair | Tightly coiled hair, oval in cross-section, with the texture of wool. (05 Mar 2000) |
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| woolly-hair nevus | A circumscribed patch of fine, curly hair in an otherwise normal scalp appearing during childhood and enlarging for a period of 2 to 3 years; autosomal dominant inheritance. There is another, mostly sporadic form that may be autosomal recessive. Synonym: allotrichia circumscripta. (05 Mar 2000) |
| cortex of hair shaft | The principal structural component of the hair shaft, composed of closely packed fusiform keratinised cells and invested by the cuticula pili. (05 Mar 2000) |
| hair | 1. The collection or mass of filaments growing from the skin of an animal, and forming a covering for a part of the head or for any part or the whole of the body. 2. One the above-mentioned filaments, consisting, in invertebrate animals, of a long, tubular part which is free and flexible, and a bulbous root imbedded in the skin. "Then read he me how Sampson lost his hairs." (Chaucer) "And draweth new delights with hoary hairs." (Spenser) 3. Hair (human or animal) used for various purposes; as, hair for stuffing cushions. 4. <zoology> A slender outgrowth from the chitinous cuticle of insects, spiders, crustaceans, and other invertebrates. Such hairs are totally unlike those of vertebrates in structure, composition, and mode of growth. 5. An outgrowth of the epidermis, consisting of one or of several cells, whether pointed, hooked, knobbed, or stellated. Internal hairs occur in the flower stalk of the yellow frog lily (Nuphar). 6. A spring device used in a hair-trigger firearm. 7. A haircloth. 8. Any very small distance, or degree; a hairbreadth. Hairs is often used adjectively or in combination; as, hairbrush or hair brush, hair dye, hair oil, hairpin, hair powder, a brush, a dye, etc, for the hair. Against the hair, in a rough and disagreeable manner; against the grain. "You go against the hair of your professions." . <anatomy> Hair bracket, the thinnest metal space used in lines of type. Hair stroke, a delicate stroke in writing. Hair trigger, a trigger so constructed as to discharge a firearm by a very slight pressure, as by the touch of a hair. Not worth a hair, of no value. To a hair, with the nicest distinction. To split hairs, to make distinctions of useless nicety. Origin: OE. Her, heer, haer, AS. Haer; akin to OFries, her, D. & G. Haar, OHG. & Icel. Har, Dan. Haar, Sw. Har; cf. Lith. Kasa. Source: Websters Dictionary (01 Mar 1998) |
| hair ball | A hair cast in the stomach or intestinal tract, common in cats. Synonym: hair ball, pilobezoar. Origin: tricho-+ bezoar (05 Mar 2000) |
| hair bulb | Hair bulb, the lower expanded extremity of the hair follicle that fits like a cap over the papilla pili. Synonym: bulbus pili, hair bulb. (05 Mar 2000) |
| hair cast | 1. A cast composed of parakeratotic scales attached to scalp hair but freely movable up and down the hair shaft; found in scaling dermatitis of the scalp, including dandruff, psoriasis, and seborrheic dermatitis. Synonym: pseudonit. 2. A small, nodular accretion of epithelial cells and keratinous debris resulting from failure of the internal root sheath to disintegrate; it appears for 3 to 7 mm along the hair shaft. (05 Mar 2000) |
| hair cell | 1. <biology> Cells found in the epithelial lining of the labyrinth of the inner ear. The hairs are stereovilli up to 25 m long that restrict the plane in which deformation of the apical membrane of the cell can be brought about by movement of fluid or by sound. Movement of the single stereocilium transduces mechanical movements into electrical receptor potentials. 2. <plant biology> Many plant surfaces are covered with fine hairs (Tradescantia stamens are a common source), the hairs are made up of thin walled cells that are convenient for studying cytoplasmic streaming and for observing mitosis. (13 Nov 1997) |
| hair cells | Mechanoreceptors located in the organ of corti that are sensitive to auditory stimuli and in the vestibular apparatus that are sensitive to movement of the head. In each case the accessory sensory structures are arranged so that appropriate stimuli cause movement of the hair-like projections (stereocilia and kinocilia) which relay the information centrally in the nervous system. (12 Dec 1998) |
| hair cells, inner | Bulbous cells that are medially placed in one row in the organ of corti. In contrast to the outer hair cells, the inner hair cells are fewer in number, have fewer sensory hairs, and are less differentiated. (12 Dec 1998) |
| hair cells, outer | Mechanoreceptors in the organ of corti. In mammals the outer hair cells are arranged in three rows which are further from the modiolus than the single row of inner hair cells. The motile properties of the outer hair cells may contribute actively to tuning the sensitivity and frequency selectivity of the cochlea. (12 Dec 1998) |
| hair cells, vestibular | Mechanoreceptors located in the acoustic maculae and the saemicircular canals that mediate the sense of balance, movement, and head position. The vestibular hair cells are connected to accessory structures in such a way that movements of the head displace their stereocilia. This influences the membrane potential of the cells which relay information about movements via the vestibular part of the acoustic nerve to the brainstem. (12 Dec 1998) |
| hair colour | Colour of hair or fur. (12 Dec 1998) |
| hair crosses | Crosslike figures formed by hairs growing from two directions that meet and then separate in a direction perpendicular to the original orientation. Synonym: hair crosses. (05 Mar 2000) |
| hair cycle | The cyclical phases of growth (anagen), regression (catagen), and quiescence (telogen) in the life of a hair. (05 Mar 2000) |