| OC | obstetrical conjugate; occlusocervical; office call; on call; only child; optic chiasma; oral contra... |
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| OPO | Organ Procurement Organization |
| OS | left eye [Lat. oculus sinister]; occipitosacral; occupational safety; office surgery; Omenn syndrome... |
| OSF | organ system failure; osteoclast-stimulating factor; outer spiral fiber; overgrowth stimulating fact... |
| OTD | oculotrichodysplasia; oral temperature device; organ tolerance dose |
| enamel organ | Epithelial cells surrounding the dental papilla and differentiated into three layers: the inner enamel epithelium, consisting of ameloblasts which eventually form the enamel, and the enamel pulp and external enamel epithelium, both of which atrophy and disappear before and upon eruption of the tooth, respectively. (12 Dec 1998) |
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| end organ | The special structure containing the terminal of a nerve fibre in peripheral tissue such as muscle, tissue, skin, mucous membrane, or glands. See: ending. (05 Mar 2000) |
| Jacobson's organ | A specialised part of the olfactory system located anteriorly in the nasal cavity within the nasal septum. Chemosensitive cells of the vomeronasal organ project via the vomeronasal nerve to the accessory olfactory bulb. The primary function of this organ appears to be in sensing pheromones which regulate reproductive and other social behaviours. While the structure has been thought absent in higher primate adults, data now suggests it may be present in adult humans. (12 Dec 1998) |
| floating organ | An organ with loose attachments, permitting its displacement. Synonym: floating organ, ptotic organ. (05 Mar 2000) |
| flower-spray organ of Ruffini | One of the two types of sensory nerve ending associated with the neuromuscular spindle (the other being the annulospiral ending); in this type, the fibre branches spread out upon the surface of the intrafusal fibres like a spray of flowers. Synonym: flower-spray organ of Ruffini. (05 Mar 2000) |
| foetal organ maturity | <embryology> Functional competence of specific foetal organs or body systems. In humans, it is usually assessed by analysis of amniotic fluid, as in the assessment of foetal lung maturity by analysis for components of pulmonary surfactant. (08 Mar 2000) |
| lateral line sense organ | A structure in fish consisting of a long groove or canal extending along each side of the trunk and tail and branching in the head region; the groove or tube is lined with neuroepithelial cells, some of which are in groups known as neuromasts; its function appears to be the detection of vibrations of low frequency. Synonym: neuromast organ. (05 Mar 2000) |
| anaesthetic shock | Shock produced by the administration of anaesthetic drug(s), usually in relative overdosage. (05 Mar 2000) |
| anaphylactic shock | <immunology> A serious, often life-threatening allergic reaction that is characterised by low blood pressure, shock (poor tissue perfusion) and difficulty breathing. (27 Sep 1997) |
| anaphylactoid shock | A reaction that is similar to anaphylactic shock, but which does not require the incubation period characteristic of induced sensitivity (anaphylaxis); it is unrelated to antigen-antibody reactions. Synonym: anaphylactoid crisis, pseudoanaphylactic shock. (05 Mar 2000) |
| break shock | The shock produced by breaking a constant current passing through the body. (05 Mar 2000) |
| cardiac shock | A form of shock (inadequate delivery of oxygen to the tissues) that occurs secondary to the weakened pumping function of the heart. This condition may be precipitated by myocardial infarction or cardiomyopathy. Treatment includes fluid restriction, diuretics, vasopressors (dopamine) to support the blood pressure and the use of intravenous medications (dobutamine) which stimulate the heart to contract more forcefully. (27 Sep 1997) |
| cardiogenic shock | A form of shock (inadequate delivery of oxygen to the tissues) that occurs secondary to the weakened pumping function of the heart. This condition may be precipitated by myocardial infarction or cardiomyopathy. Treatment includes fluid restriction, diuretics, vasopressors (dopamine) to support the blood pressure and the use of intravenous medications (dobutamine) which stimulate the heart to contract more forcefully. (27 Sep 1997) |
| cardiopulmonary obstructive shock | <cardiology> This term describes a number of conditions that involve a severe disturbance of the cardiopulmonary circuit resulting in shock (inadequate delivery of oxygen to the tissues). Examples include: pulmonary embolism, pericardial tamponade, pneumothorax and constrictive pericarditis. (27 Sep 1997) |
| vasogenic shock | Shock resulting from depressed activity of the higher vasomotor centres in the brain stem and the medulla, producing vasodilation without loss of fluid so that the container is disproportionately large. In oligaemic shock, blood volume is reduced; in both, return of venous blood is inadequate. (05 Mar 2000) |