| extraction | The process or act of pulling or drawing out. Origin: L. Trahere = to draw (18 Nov 1997) |
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| extraction and processing industry | The industry concerned with the removal of raw materials from the earth's crust and with their conversion into refined products. (12 Dec 1998) |
| extraction coefficient | The percentage of a substance removed from the blood or plasma in a single passage through a tissue; e.g., the extraction coefficient for p-aminohippuric acid (PAH) in the kidney is the difference between arterial and renal venous plasma PAH concentrations, divided by the arterial plasma PAH concentration. (05 Mar 2000) |
| extraction, obstetrical | Extraction of the foetus by means of obstetrical instruments. (12 Dec 1998) |
| extraction ratio | The fraction of a substance removed from the blood flowing through the kidney; it is calculated from the formula (A -V)/A, where A and V, respectively, are the concentrations of the substance in arterial and renal venous plasma. (05 Mar 2000) |
| annular cataract | Congenital cataract in which a central white membrane replaces the nucleus. Synonym: disk-shaped cataract, life-belt cataract, umbilicated cataract. (05 Mar 2000) |
| arborescent cataract | An obsolete term for dendritic cataract. (05 Mar 2000) |
| atopic cataract | A cataract associated with atopic dermatitis. (05 Mar 2000) |
| axial cataract | A lenticular opacity in the visual axis of the lens. (05 Mar 2000) |
| black cataract | A cataract in which the lens is hardened and of a dark brown colour. In the 19th century, German black cataract meant gutta severa (q.v.). Synonym: cataracta brunescens, cataracta nigra. (05 Mar 2000) |
| blue cataract | Coronary cataract of bluish colour. Synonym: cataracta cerulea. (05 Mar 2000) |
| capsular cataract | A cataract in which the opacity affects the capsule only. (05 Mar 2000) |
| capsulolenticular cataract | A cataract in which both the lens and its capsule are involved. See: membranous cataract. (05 Mar 2000) |
| galactose cataract | A neonatal cataract associated with intralenticular accumulation of galactose alcohol. See: galactosaemia. (05 Mar 2000) |
| radiation cataract | A cataract caused by excessive or prolonged exposure to ultraviolet rays, X-rays, radium, beta rays, gamma rays, heat, or radioactive isotopes. (05 Mar 2000) |