| MHS | major histocompatibility system; malignant hyperthermia in swine; malignant hyperthermia syndrome; m... |
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| PDS | pain-dysfunction syndrome; paroxysmal depolarizing shift; patient data system; Patient-Doctor Societ... |
| PNS | paraneoplastic syndrome; parasympathetic nervous system; partial nonprogressive stroke; peripheral n... |
| PPS | Personal Preference Scale; physician, patient and society [course]; polyvalent pneumococcal polysacc... |
| RAS | rapid atrial stimulation; recurrent aphthous stomatitis; reflex activating stimulus; reliability, av... |
| integumentary system | The skin, hair, and nails; derived from ectoderm and subjacent mesoderm. (05 Mar 2000) |
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| intermediary system | One of the lamellae of partially resorbed osteons occurring between newer, complete osteons. Synonym: ground lamella, intermediary system, intermediate lamella. (05 Mar 2000) |
| international system of units | A system of physical units in which the fundamental quantities are length, time, mass, electric current, temperature, luminous intensity, and amount of substance, and the corresponding units are the meter, second, kilogram, ampere, kelvin, candela, and mole. The system has been given official status and recommended for universal use by the general conference on weights and measures. (12 Dec 1998) |
| interofective system | Term applied by W. Cannon to the autonomic nervous system as opposed to the somatic nervous system or exterofective system. (05 Mar 2000) |
| 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) |