| dark current | <physiology> Current caused by constant influx of sodium ions into the rod outer segment of retinal photoreceptors and that is blocked by light (leading to hyperpolarization). The plasma membrane sodium channel is controlled through a cascade of amplification reactions initiated by photon capture by rhodopsin in the disc membrane. (18 Nov 1997) |
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| d'Arsonval current | An alternating electric current having a frequency of 10,000 or more per second; it produces no muscular contractions and does not affect the sensory nerves. Synonym: d'Arsonval current, Tesla current. (05 Mar 2000) |
| demarcation current | The current set up when an injured part of a nerve, muscle, or other excitable tissue is connected through a conductor with the uninjured region; the injured tissue is negative to the uninjured. Synonym: demarcation current. (05 Mar 2000) |
| descending current | The direction of current flow in a nerve when the cathode is placed peripheral to the anode, in contrast to ascending current. Synonym: centrifugal current. (05 Mar 2000) |
| direct current | (DC) Electric current which travels continuously in the same direction over a sustained period of time, contrast with AC (Alternating Current) which oscillates as a function of time. (09 Oct 1997) |
| inductive current drive | <physics> Method to drive current in a toroidal plasma by using the torus of conducting plasma as the second coil in a transformer. The primary coil usually runs down the centre of the torus, changes in the current driven through the primary coil create changing magnetic fields which drive current in the plasma. The current thus driven can be used to heat the plasma as well (see also ohmic heating, induction). (09 Oct 1997) |
| Tesla current | An alternating electric current having a frequency of 10,000 or more per second; it produces no muscular contractions and does not affect the sensory nerves. Synonym: d'Arsonval current, Tesla current. (05 Mar 2000) |
| eddy current | <radiobiology> Electric current induced inside a conductor when the conductor (a) moves through a nonuniform magnetic field, or (b) experiences a change in the magnetic flux through its surface. (09 Oct 1997) |
| eddy-current loss | <radiobiology> Energy loss due to eddy currents circulating in a resistive material. (09 Oct 1997) |
| toroidal current | <radiobiology> Current flowing in the toroidal direction (the long way) around a torus. (As distinct from poloidal currents flowing through the centre of the torus and around to the outside, the short way.) (09 Oct 1997) |
| labile current | An electrical current applied to the body by means of electrodes that are constantly shifted about. (05 Mar 2000) |
| acquired platelet function defect | <haematology> Platelet function can be affected by a number of different disease processes including polycythaemia vera, leukaemia, myelofibrosis, renal failure, multiple myeloma and some medications (for example penicillins, salicylates, phenothiazines). Disturbed blood clotting can be manifested by: easy bruising, bleeding gums, nosebleeds, abnormal vaginal bleeding, rectal bleeding, skin rash, vomiting blood, coughing up blood or blood in the urine. A measure of bleeding time and coagulation profile will be part of the evaluation. (29 Dec 1997) |
| allomeric function | The combined function of the several segments of the spinal cord and medulla, communicating with each other by means of the white matter. (05 Mar 2000) |
| aperture function | <microscopy> In a diffraction-limited optical system, the function that determines the relationship between the image and each point in the object. Modifying the aperture function changes the image according to the modified Fourier-filtering (or optical filtration) property of the aperture. (05 Aug 1998) |
| arousal function | The ability of a sensory event to arouse the cortex to vigilance or readiness. (05 Mar 2000) |