| free margin of eyelids | The unattached inferior edge of the upper lid and superior edge of the lower lid, where the anterior (cutaneous) surface of the eyelid meets the posterior (conjunctival) surface of the eyelid. The free margins of the eyelids bound the rima palpebrarum, and each free margin has an anterior and posterior border. See: borders of eyelids. (05 Mar 2000) |
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| free-milling | Yielding free gold or silver; said of certain ores which can be reduced by crushing and amalgamation, without roasting or other chemical treatment. Source: Websters Dictionary (01 Mar 1998) |
| free nerve endings | A form of peripheral ending of sensory nerve fibres in which the terminal filaments end freely in the tissue. Synonym: terminationes nervorum liberae. (05 Mar 2000) |
| free radical | A chemically active atom or molecular fragment containing a chemical charge due to an excess or deficient number of electrons. Radicals seek to receive or release electrons in order to achieve a more stable configuration, a process that can damage the large molecules within cells. See: Oxidation. (09 Oct 1997) |
| free radical reductase | <enzyme> Catalyses conversion of carbon-centreed lipid radicals into an inactive species by utilizing vitamin e at one end and glutathione at the other Registry number: EC 1.8.4.- (26 Jun 1999) |
| free radicals | Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated. (12 Dec 1998) |
| free radical scavengers | Substances that influence the course of a chemical reaction by ready combination with free radicals. Among other effects, this combining activity protects pancreatic islets against damage by cytokines and prevents myocardial and pulmonary perfusion injuries. (12 Dec 1998) |
| free-swimming | <zoology> Swimming in the open sea; said of certain marine animals. Source: Websters Dictionary (01 Mar 1998) |
| free tenia | See: teniae coli. Synonym: tenia libera. (05 Mar 2000) |
| free thyroxine index | An arbitrary value obtained by multiplying the triiodothyronine uptake by the serum thyroxine concentration; it largely corrects for variations in thyroid-bound globulin concentration by providing a clinically valid estimate of the physiologically active free thyroxine; direct assay or laboratory measurement of free serum thyroxine yields a more accurate value. (05 Mar 2000) |
| free villus | A chorionic villus that is not attached to the decidua basalis, but is "free" in the maternal blood of the intervillous spaces. Synonym: floating villus. (05 Mar 2000) |
| free water | Water in the body that can be removed by ultrafiltration and in which substances can be dissolved. (05 Mar 2000) |
| free water clearance | The amount of water excreted in the urine beyond that which would accompany the excreted solutes if the urine were isosmotic with plasma; it represents the loss of body water in excess of solute tending to raise body osmolality and making urine hyposmotic. Unlike other clearance's, it is calculated by subtracting the osmolal clearance from the actual volume of urine excreted per minute. A negative value for free water clearance represents the amount of water that the body has reclaimed from isosmotic tubule fluid to make the urine hyperosmotic and to lower body osmolality. (05 Mar 2000) |
| free wave | <radiobiology> A wave (for example, electromagnetic) traveling in a homogeneous infinite medium (no boundary conditions). (09 Oct 1997) |
| free will | 1. A will free from improper coercion or restraint. "To come thus was I not constrained, but did On my free will." (Shak) 2. The power asserted of moral beings of willing or choosing without the restraints of physical or absolute necessity. Source: Websters Dictionary (01 Mar 1998) |