| GAN | giant axon neuropathy |
|---|---|
| JVP | [POMD P 49 - 52] 1) Jugular Vein Pressure 2) Jugular Venous Pulse ... |
| GCT | general care and treatment; germ-cell tumor; giant cell thyroiditis; giant cell tumor |
| GnRH | Gonadotropin Releasing Hormone [HP 1898, 2034] = LHRH = Go... |
| MA | malignant arrhythmia; management and administration; mandelic acid; masseter; Master of Arts; matern... |
| MGA | medial giant axon |
|---|---|
| Q-SART | Quantitative Sudomotor Axon Reflex Test |
| CGC | cerebral giant cell |
| FBGC | Foreign Body Giant Cell |
| GT | Giant |
| giant axon | <biology> Extraordinarily large unmyelinated axons found in invertebrates. Some, like the squid giant axon, can approach 1 mm diameter. Large axons have high conduction speeds, the giant axons are invariably involved in panic or escape responses and may (e.g. Crayfish) have electrical synapses to further increase speed. Vertebrate axons with high conduction velocites are much narrower: they are myelinated, allowing saltatory conduction. (17 Dec 1997) |
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| giant axonal neuropathy | <paediatrics> A rare disorder beginning at or after the third year of life, and presenting clinically with kinky hair, progressive painless clumsiness, muscle weakness and atrophy, sensory loss, and areflexia. Pathologically, both myelinated and unmyelinated nerve fibres contain axonal spheroids packed with neurofilaments; sporadic in nature. (05 Mar 2000) |
| squid giant axon | <physiology> Large axons, up to 1mm in diameter, that innervate the mantle of the squid. Because of their large size, many of the pioneering investigations of the mechanisms underlying resting and action potentials in excitable cells were done on these fibres. (10 Mar 1998) |
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| axon | <cell biology> A long process of a neuron, that carries efferent (outgoing) action potentials from the cell body towards target cells. Each nerve cell has one axon, which can be over a foot long. A nerve cell communicates with another nerve cell by transmitting signals from the branches at the end of its axon. At the terminal end of the axon, the impulses are transmitted to other nerve cells or to effector organs. In the peripheral nervous system, the larger (myelinated) axons are surrounded by a myelin sheath formed by concentric layers of plasma membrane of the schwann cell. In the central nervous system, the function of the schwann cell is supplied by oligodendrocytes (oligodendroglia). See: dendrite. (03 Jul 1999) |
| axon degeneration | A type of peripheral nerve fibre response to insult, wherein axon death and subsequent breakdown occurs, with secondary breakdown of the myelin sheath associated; caused by focal injury to peripheral nerve fibres; often referred to as wallerian degeneration. Synonym: axon degeneration. (05 Mar 2000) |
| axon hillock | <cell biology> Tapering region between a neuron's cell body and its axon. This region is responsible for summating the graded inputs from the dendrites and producing action potentials if the threshold is exceeded. (12 Mar 1998) |
| axon loss polyneuropathy | A type of polyneuropathy in which axon degeneration is the sole/predominant feature; many aetiologies, particularly toxic and metabolic; on nerve conduction studies, affects amplitudes of the responses, but does not cause conduction slowing or block. Synonym: axonal polyneuropathy. (05 Mar 2000) |
| axon reflex | An effect brought about by the passage of the nerve impulses from a sensory ending to the effector organ along divisions of the nerve fibre without traversing a synapse, e.g., as in the vasodilation resulting from stimulation of the skin or the irritation of the conjunctiva; the reaction occurs even when the nerve fibre has been sectioned and thus isolated from the nervous centres. (05 Mar 2000) |
| axon terminals | The somewhat enlarged, often club-shaped endings by which axons make synaptic contacts with other nerve cells or with effector cells (muscle or gland cells). As isolated, by homogenizing brain or spinal cord, they contain acetylcholine and the related enzymes. Terminals contain neurotransmitters of various kinds, sometimes more than one. These can be demonstrated by chemical analysis and immunocytochemical methods. See: synapse. Synonym: axonal terminal boutons, end-feet, neuropodia, pieds terminaux, synaptic boutons, synaptic endings, synaptic terminals, terminal boutons, bouton terminaux. (05 Mar 2000) |
| cervix of the axon | The constricted portion of the axon just before the myelin sheath begins. (05 Mar 2000) |
| benign giant lymph node hyperplasia | Solitary masses of lymphoid tissue containing concentric perivascular aggregates of lymphocytes, occurring usually in the mediastinum or hilar region of young adults; similar changes have been reported outside the mediastinum and, if associated with interfollicular sheets of plasma cells, may progress to lymphoma or plasmacytoma. Synonym: angiofollicular mediastinal lymph node hyperplasia, Castleman's disease. (05 Mar 2000) |
| carcinoma, giant cell | An epithelial neoplasm characterised by unusually large anaplastic cells. It is highly malignant with fulminant clinical course, bizarre histologic appearance and poor prognosis. It is most common in the lung and thyroid. (12 Dec 1998) |
| malignant giant cell tumour | A type of bone tumour. (12 Dec 1998) |
| giant | 1. A man of extraordinari bulk and stature. "Giants of mighty bone and bold emprise." 2. A person of extraordinary strength or powers, bodily or intellectual. 3. Any animal, plant, or thing, of extraordinary size or power. Giant's Causeway, a vast collection of basaltic pillars, in the county of Antrim on the northern coast of Ireland. Origin: OE. Giant, geant, geaunt, OF. Jaiant, geant, F. Geant, L. Gigas, fr. Gr, from the root of E. Gender, genesis. See Gender, and cf. Gigantic. Like a giant; extraordinary in size, strength, or power; as, giant brothers; a giant son. Giant cell. <anatomy> A very large African heron (Ardeomega goliath). It is the largest heron known. Giant kettle, a pothole of very large dimensions, as found in Norway in connection with glaciers. See Pothole. Giant powder. See Nitroglycerin. <botany> Giant puffball, one of several species of very large squids, belonging to Architeuthis and allied genera. Some are over forty feet long. Source: Websters Dictionary (01 Mar 1998) |
| giant cell | <pathology> A cell of large size, often with many nuclei. They are multinucleated masses produced by the fusion of many cells. They are often associated with viral infections. In AIDS, they are induced when the envelope glycoprotein of HIV binds to the CD4 antigen of uninfected neighboring T4 cells. The resulting syncytium leads to cell death and thus may account for the cytopathic effect of the virus. (18 Jul 2002) |
| giant cell aortitis | <pathology> Giant cell arteritis involving the aorta. (05 Mar 2000) |
| giant cell arteritis | <pathology> An inflammatory condition of the temporal artery. It is a serious chronic vascular disease, characterised by inflammation of the walls of the blood vessels (vasculitis). The age of affected patients is usually over 50 years of age. It most often involves the carotid artery system, and can lead to blindness or stroke. It can be diagnosed by biopsy of an artery, but there is often a false negative result. Elevation of the erythrocyte sedimentation rate is typical. Treatment is with high dose steroids. Common symptoms include headaches and tenderness over the temple (temporal artery). Can be associated with polymyalgia rheumatica. See: polymyalgia rheumatica. Synonym: cranial arteritis, temporal arteritis (20 Jun 2000) |
| giant axonal n. |
an autosomal recessive neuropathy of childhood characterized by enlarged axons made up of masses of tightly woven neurofilaments.
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