| horizontal plate of palatine bone | The part of the palatine bone that forms the posterior part (approximately one third) of the bony palate. Synonym: lamina horizontalis ossis palatini. (05 Mar 2000) |
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| horizontal resorption | A progressive loss of alveolar and supporting bone surrounding the teeth, beginning at the most coronal level of the bone. Synonym: horizontal resorption. (05 Mar 2000) |
| horizontal survey | <epidemiology> A study of a community, perhaps stratified by age, sex, ethnicity etc., but at one point in time or over a short time interval. Although a snapshot, horizontal surveys of prevalence and intensity within different age classes of a community can nevertheless provide valuable information on the rate at which hosts acquire infection through time, provided that the host and parasite populations have remained approximately stable for a period of time (i.e. Stable endemicity). Same as cross-sectional study , converse of longitudinal study. (05 Dec 1998) |
| horizontal transmission | <epidemiology> Transmission occurring generally within a population, but not including vertical transmission. (05 Dec 1998) |
| horizontal vertigo | Dizziness experienced on lying down. (05 Mar 2000) |
| horizontalis | Horizontal, referring to the plane of the body, perpendicular to the vertical plane, at right angles both to the median and coronal planes, that separates the body into upper and lower parts. Origin: L. (05 Mar 2000) |
| hormesis | An effect where a toxic substance acts like a stimulant in small doses, but it is an inhibitor in large doses. (09 Oct 1997) |
| hormion | A craniometric point at the junction of the posterior border of the vomer with the sphenoid bone. Origin: G. Hormos, cord, chain, necklace (05 Mar 2000) |
| hormogonal | Referring to a class of Cyanobacteria in which the cells grow in filaments. (05 Mar 2000) |
| hormogonium | <botany> A chain of small cells in certain algae, by which the plant is propogated. Origin: NL, fr. Gr. A chain + generation. Source: Websters Dictionary (01 Mar 1998) |
| hormonal | Pertaining to or of the nature of a hormone. (18 Nov 1997) |
| hormonal gingivitis | Gingivitis in which the host response to bacterial plaque is presumably exacerbated by hormonal alterations occurring during puberty, pregnancy, oral contraceptive use, or menopause. (05 Mar 2000) |
| hormonal therapy | Treatment of cancer by alteration of the hormonal balance. Some cancer will only grow in the presence of certain hormones. (09 Oct 1997) |
| hormone | <endocrinology> A naturally occuring substance secreted by specialised cells that affects the metabolism or behaviour of other cells possessing functional receptors for the hormone. Hormones may be hydrophilic, like insulin, in which case the receptors are on the cell surface or lipophilic, like the steroids, where the receptor can be intracellular. Some cancers may be stimulated and others inhibited by hormones (for example breast and prostate cancer). Some hormones can be synthesised and used as replacement in glandular deficiencies or as treatment for some cancers. Hormones may be injected, others taken by mouth. (29 Sep 1997) |
| hormone antagonists | Chemical substances which inhibit the function of the endocrine glands, the biosynthesis of their secreted hormones, or the action of hormones upon their specific sites. (12 Dec 1998) |