| GMS | General Medical Service; geriatric mental state; Gilbert-Meulengracht syndrome; Gomori methenamine s... |
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| PASM | periodic acid-silver methenamine |
| PA-T-SP | periodic acid-thiocarbo-hydrazide-silver proteinate |
| RSS | rat stomach strip; rectosigmoidoscopy; Russell-Silver syndrome |
| SDS | same day surgery; school dental services; self-rating depression scale; sensory deprivation syndrome... |
| food ball | A gastric concretion formed of vegetable fibres, with the seeds and skins of fruits, and sometimes starch granules and fat globules. Synonym: food ball. Origin: phyto-+ bezoar (05 Mar 2000) |
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| fungus ball | A compact mass of fungal mycelium and cellular debris, 1 to 5 cm in diameter, residing within a lung cavity; such cavities may be produced by bacterial as well as mycotic infectious agents, but they are usually produced by Aspergillus fumigatus or, more rarely, by A. Niger. See: aspergilloma. (05 Mar 2000) |
| active electrode | A small electrode whose exciting effect is used to stimulate or record potentials from a localised area. Synonym: exciting electrode, localizing electrode, therapeutic electrode. (05 Mar 2000) |
| calomel electrode | An electrode in which the wire is connected through a pool of mercury to a paste of mercurous chloride (Hg2Cl2, calomel) in a potassium chloride solution covered by more potassium chloride solution; commonly used as a reference electrode. (05 Mar 2000) |
| carbon dioxide electrode | A glass electrode in a film of bicarbonate solution covered by a thin plastic membrane permeable to carbon dioxide but impermeable to water and electrolytes; the carbon dioxide pressure of a gas or liquid sample quickly equilibrates through the membrane and is measured in terms of the resulting pH of the bicarbonate solution, as sensed by the glass electrode; commonly used to analyze arterial blood samples. Synonym: Severinghaus electrode. (05 Mar 2000) |
| redox electrode | An electrode capable of measuring oxidation-reduction potential. See: quinhydrone electrode. Synonym: redox electrode. (05 Mar 2000) |
| reference electrode | An electrode expected to have a constant potential, such as a calomel electrode, and used with another electrode to complete an electrical circuit through a solution; e.g., when a reference electrode is used with a glass electrode for pH measurement, changes in voltage between the two electrode's can be attributed to the effects of pH on the glass electrode alone. (05 Mar 2000) |
| glass electrode | A thin-walled glass bulb containing a standard buffer solution, quinhydrone, and a platinum wire; when immersed in an unknown solution, a potential difference develops that varies with the pH of the unknown solution; this difference can be made to give the pH; used in pH meters. (05 Mar 2000) |
| central terminal electrode | In electrocardiography, an electrode in which connections from the three limbs (right arm, left arm, and left leg) are joined and led to the electrocardiograph to form the indifferent electrode, theoretically at zero potential for the system. (05 Mar 2000) |
| Clark electrode | An oxygen electrode consisting of the tip of a platinum wire exposed to a thin film of electrolyte covered by a plastic membrane permeable to oxygen but not to water or the electrolyte. When a certain voltage is applied, oxygen is destroyed at the platinum surface; the flow of current is then proportional to the rate at which oxygen can diffuse to the platinum surface from the gas or liquid sample outside the membrane, and is thus a measure of the oxygen pressure in the sample; commonly used to measure oxygen pressure in arterial blood samples. (05 Mar 2000) |
| positive electrode | <microscopy> The electrode to which a major flow of electrons takes place internally (as in a cathode-ray tube) or to which an external positive voltage supply is connected. (05 Aug 1998) |
| Severinghaus electrode | A glass electrode in a film of bicarbonate solution covered by a thin plastic membrane permeable to carbon dioxide but impermeable to water and electrolytes; the carbon dioxide pressure of a gas or liquid sample quickly equilibrates through the membrane and is measured in terms of the resulting pH of the bicarbonate solution, as sensed by the glass electrode; commonly used to analyze arterial blood samples. Synonym: Severinghaus electrode. (05 Mar 2000) |
| hydrogen electrode | The ultimate standard of reference in all pH determinations, limited and technically difficult to use, consisting of a piece of spongy platinum black partly immersed in a solution in a small glass tube; the tube above the solution is filled with hydrogen gas that is bubbled through the solution and absorbed by the platinum; the electrode thus measures the potential between H2 and H+, the "standard" potential of which (1 atmosphere, 1 molar) is taken as zero; hence, the hydrogen electrode potential measures [H+] or pH. (05 Mar 2000) |
| silent electrode | In unipolar electrocardiography, a remote electrode placed either upon a single limb or connected with the central terminal and paired with an exploring electrode; the indifferent electrode is supposed to contribute little or nothing to the resulting record. Synonym: dispersing electrode, silent electrode. (05 Mar 2000) |
| negative electrode | <chemistry, physics> The electrode in an electrochemical cell toward which cations are drawn and where reduction occurs. The negatively charged electrode in a vacuum tube. (16 Mar 1998) |