| oxidation-reduction indicator | A substance that undergoes a definite colour change at a specific oxidation potential. Synonym: redox indicator. (05 Mar 2000) |
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| oxidation-reduction potential | <chemistry, physics> The potential in volts of an inert metallic electrode measured in a system of an arbitrarily chosen ratio of [oxidant] to [reductant] and referred to the normal hydrogen electrode at absolute temperature. It is calculated from the following equation: where R is the gas constant expressed in electrical units, T the absolute temperature (Kelvin), n the number of electrons transferred, F the faraday and E0 the normal symbol for the potential of the system at pH 0; for biological systems E0' is often used (in which pH = 7). Compare: Nernst's equation. Synonym: redox potential. (05 Mar 2000) |
| oxidation-reduction reaction | <chemistry> Any reaction in which electrons are removed from one molecule or atom and given to another molecule or atom. (09 Oct 1997) |
| oxidation-reduction system | <enzyme> An enzyme system in the tissues by which oxidation and reduction proceed simultaneously through the transference of hydrogen or of one or more electrons from one metabolite to another. See: oxidation-reduction. Synonym: redox system. (05 Mar 2000) |
| tuberosity reduction | The surgical excision of excessive fibrous or bony tissue in the area of the maxillary tuberosity prior to the construction of prosthetic appliances. (05 Mar 2000) |
| abnormal cleavage of cardiac valve | Congenital malformation of a valve leaflet with a defect extending from the free margin. (05 Mar 2000) |
| anterior cardiac veins | Two or three small veins in the anterior wall of the right ventricle opening directly into the right atrium independently of the coronary sinus. Synonym: venae cordis anteriores. (05 Mar 2000) |
| area of cardiac dullness | A triangular area determined by percussion of the front of the chest; it corresponds to the part of the heart that is not covered by lung tissue. (05 Mar 2000) |
| cardiac | <cardiology> Pertaining to the heart. Origin: L. Cardiacus from Gr. Kardiakos (16 Dec 1997) |
| cardiac accident | Sudden cardiac catastrophe, such as may result from coronary occlusion. (05 Mar 2000) |
| cardiac albuminuria | Albuminuria caused by congestive heart failure. (05 Mar 2000) |
| cardiac alternation | The occurrence of any cardiac phenomenon every other beat. (05 Mar 2000) |
| cardiac aneurysm | Thinning, stretching, and bulging of a weakened ventricular wall, usually as a result of myocardial infarction; rarely postinflammatory or congenital. Synonym: mural aneurysm, ventricular aneurysm. (05 Mar 2000) |
| cardiac arrest | This refers to the complete cessation of cardiac activity (heartbeat). (27 Sep 1997) |
| cardiac arrhythmia | A disturbance the electrical activity of the heart that manifests as an abnormality in heart rate or heart rhythm. Patients with a cardiac arrhythmia may experience a wide variety of symptoms ranging from palpitations to fainting. (27 Sep 1997) |