| ANS | acanthion; American Nutrition Society; 8-anilino-1-naphthalene-sulfonic acid; anterior nasal spine; ... |
|---|---|
| APS | adenosine phosphosulfate; American Pain Society; American Pediatric Society; American Physiological ... |
| ARAMIS | American Rheumatism Association Medical Information System |
| ARAS | ascending reticular activating system |
| ARSM | acute respiratory system malfunction |
| involuntary nervous system | <anatomy> Neurons that are not under conscious control, comprising two antagonistic components, the sympathetic and parasympathetic nervous systems. The autonomic nervous system regulates key functions including the activity of the cardiac (heart) muscle, smooth muscles (e.g., of the gut), and glands. The autonomic nervous system has two divisions: 1. The sympathetic nervous system that accelerates the heart rate, constricts blood vessels, and raises blood pressure. 2. The parasympathetic nervous system slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles. (03 Jul 1999) |
|---|---|
| isolated system | <chemistry> A system which can exchange neither mass nor energy with its surroundings. (09 Jan 1998) |
| occlusal system | The form or design and arrangement of the occlusal and incisal units of a dentition or the teeth on a denture. Synonym: occlusal scheme. (05 Mar 2000) |
| oculomotor system | That part of the central nervous system having to do with eye movements; it is composed of pathways connecting various regions of the cerebrum, brainstem, and ocular nuclei, utilizing multisynaptic articulations. (05 Mar 2000) |
| open system | A system that exchanges energy and materials with the outside environment. (09 Oct 1997) |
| O-R system | <abbreviation> Oxidation-reduction system. (05 Mar 2000) |
| osseous part of skeletal system | The part of the skeleton composed of bone. Synonym: pars ossea systematis skeletalis. (05 Mar 2000) |
| oxidation-reduction system | <enzyme> An enzyme system in the tissues by which oxidation and reduction proceed simultaneously through the transference of hydrogen or of one or more electrons from one metabolite to another. See: oxidation-reduction. Synonym: redox system. (05 Mar 2000) |
| thoracolumbar system | See: autonomic nervous system, sympathetic part. (05 Mar 2000) |
| 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) |
| 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) |
| 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) |