| PTRA | percutaneous transluminal renal angioplasty |
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| RA | radioactive; ragocyte; ragweed antigen; rapidly adapting [receptors]; reactive arthritis; reciprocal... |
| RALPH | renal-anal-lung-polydactylyhamartoblastoma [syndrome] |
| RAP | recurrent abdominal pain; regression-associated protein; renal artery pressure; resident assessment ... |
| RBF | regional blood flow; regional bone mass; renal blood flow |
| ecological system | <ecology> An ecosystem is the dynamic and interrelating complex of plant and animal communities and their associated non-living environment. The physical and climactic features and all the living and dead organisms in an area that are interrelated in the transfer of energy and material. An interacting complex of a community and its environment functioning as an ecological unit in nature. Differs from system in being a more rigorous definition that encompasses and requires assumptions of energetics, ecological interactions, species adaptations and so forth. (13 Nov 1997) |
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| electron optical system | <apparatus> A combination of parts capable of producing and controlling a beam of electrons to produce an image of an object. (05 Aug 1998) |
| electron transport system | The mitochondrial electron transport chain. (18 Nov 1997) |
| endocrine system | The system of glands that release their secretions (hormones) directly into the circulatory system. In addition to the endocrine glands, included are the chromaffin system and the neurosecretory systems. (12 Dec 1998) |
| endomembrane system | <cell biology> Membrane system that ramifies through the cytoplasm. The membranes of the endoplasmic reticulum are separated by 50-200 nm and the cisternal space thus enclosed constitutes a separate compartment. The Golgi region is composed of flattened sacs of membrane that together with endoplasmic reticulum and lysosomes constitute the GERL system. See: smooth endoplasmic reticulum, rough endoplasmic reticulum. (18 Nov 1997) |
| endoscopy, digestive system | Visual examination of the digestive tract by means of a fibreoptic endoscope. It is used to localise, identify, and photograph pathologic alterations, to obtain biopsy material and perform other surgical interventions, and for delivery of medication. (12 Dec 1998) |
| enteric nervous system | Two ganglionated neural plexuses in the gut wall which form one of the three major divisions of the autonomic nervous system. The enteric nervous system innervates the gastrointestinal tract, the pancreas, and the gallbladder. It contains sensory neurons, interneurons, and motor neurons. Thus the circuitry can autonomously sense the tension and the chemical environment in the gut and regulate blood vessel tone, motility, secretions, and fluid transport. The system is itself governed by the central nervous system and receives both parasympathetic and sympathetic innervation. (12 Dec 1998) |
| triaxial reference system | The figure resulting from rearranging the lines of derivation of the three standard limb leads of the electrocardiogram (as represented in Einthoven's triangle) so that, instead of forming the sides of an equilateral triangle, they bisect one another. Synonym: Dieuaide diagram. (05 Mar 2000) |
| trigeminal system | <neurology> Neurons associated with the fifth or trigeminal nerve, the largest cranial nerve. The trigeminal system provides sensory innervation to the face and mucous membrane of the oral cavity, along with motor innervation to the muscles of mastication. It is called trigeminal because it has three major peripheral branches, the opthalmic, the maxillary and the mandibular nerves. (18 Nov 1997) |
| T system | The transverse tubules that are continuous with the sarcolemma in skeletal and cardiac muscle fibres. (05 Mar 2000) |
| esthesiodic system | A system of neurons and fibre tracts in the spinal cord and brain subserving sensation. (05 Mar 2000) |
| Jamin Lebedeff system | <apparatus> Interference microscopy in which object and reference beams are split and later recombined by birefringent calcite plates, but pass through the same optical components (in contrast to the Mach Zehnder system). (18 Nov 1997) |
| turnkey system | A system which is built, engineered, and installed to the point of readiness for operation by the owner. (05 Dec 1998) |
| expert system | Expert systems are computer programs designed to simulate the problem-solving behaviour of human experts within very narrow domains or scientific disciplines (entomology, plant pathology, etc.). This discipline is a sub-set of Artificial Intelligence. See: artificial intelligence. Synonym: knowledge-based systems (13 Jan 1998) |
| expression system | <molecular biology> Combination of an expression vector, its cloned DNA, and the host for the vector that provide a context to allow foreign gene function in a host cell, that is, produce proteins at a high level. (13 Nov 1997) |