| PFU | plaque-forming unit; pock-forming unit |
|---|---|
| PICU | pediatric intensive care unit; pulmonary intensive care unit |
| PSU | photosynthetic unit; primary sampling unit |
| PU | palindromic unit; passed urine; pepsin unit; peptic ulcer; pregnancy urine; 6-propyluracil; prostati... |
| RTU | real-time ultrasonography; relative time unit; renal transplantation unit |
| metameric nervous system | That part of the nervous system which innervates body structures developed in ontogeny from the segmentally arranged somites or, in the head region, branchial arches. The term implies reference to the neural mechanisms intrinsic to the spinal cord and brainstem (represented by the sensory nuclei, motoneuronal cell groups, and their associated interneurons in the reticular formation); by strict definition it should exclude the autonomic nervous system. (05 Mar 2000) |
|---|---|
| meter-kilogram-second system | An absolute system based on the meter, kilogram, and second; the basis of the International System of Units. (05 Mar 2000) |
| cholinergic system | <physiology> The system of nerve cells that uses acetylcholine as its neurotransmitter, nerve cells in the cholinergic system are damaged in the brains of Alzheimer patients. (15 Jan 1998) |
| metric system | A system of weights and measures, universal for scientific use, based upon the meter, which was originally intended to be one ten-millionth of a quadrant of the earth's meridian and now is based on the length that light travels in a vacuum in a given period of time (see meter). Prefixes of the meter (and other standards) reflect either fractions or multiples of the meter and are identical to the International System of Units (see International System of Units). The unit of weight is the gram, which is the weight of one cubic centimeter of water, equivalent to 15.432358 grains. The unit of volume is the liter or one cubic decimeter, equal to 1.056688 U.S. Liquid quarts; a cubic centimeter is about 16.23073 U.S. Minims. (05 Mar 2000) |
| chromaffin system | The cells of the body which stain with chromium salts. They occur along the sympathetic nerves, in the adrenal gland, and in various other organs. (12 Dec 1998) |
| rootlet system | <plant biology> Microtubules associated with the base of the flagellum in ciliates and flagellates. Also associated with this region is the rhizoplast. (18 Nov 1997) |
| circulatory system | The circulatory system is a composed of the heart, arteries, capillaries and veins. It serves to transport blood low in oxygen from the body to the lungs and heart (veins) and oxygenated blood from the lungs and heart throughout the body (arteries). (see heart, blood). (12 Dec 1998) |
| phosphoenolpyruvate sugar phosphotransferase system | <enzyme> The bacterial sugar phosphotransferase system (pts) that catalyses the transfer of the phosphoryl group from phosphoenolpyruvate to its sugar substrates (the pts sugars) concomitant with the translocation of these sugars across the bacterial membrane. The phosphorylation of a given sugar requires four proteins, two general proteins, enzyme I and hpr and a pair of sugar-specific proteins designated as the enzyme II complex. The pts has also been implicated in the induction of synthesis of some catabolic enzyme systems required for the utilization of sugars that are not substrates of the pts as well as the regulation of the activity of adenylate cyclase. Registry number: EC 2.7.1.- (12 Dec 1998) |
| closed system | <biology, ecology> A chemical or biological system that exchanges no matter or energy with the ouside environment. (12 Mar 1998) |
| mnss blood-group system | A system of universal human blood group isoantigens with many associated subgroups. The m and n traits are codominant and the s and s traits are probably very closely linked alleles, including the u antigen. This system is most frequently used in paternity studies. (12 Dec 1998) |
| Pinel's system | The abolition of forcible restraint in the treatment of the mental hospital patient. (05 Mar 2000) |
| mononuclear phagocyte system | A widely distributed collection of both free and fixed macrophages derived from bone marrow precursor cells by way of monocytes; their substantial phagocytic activity is mediated by immunoglobulin and the serum complement system. In both connective and lymphoid tissue, they may occur as free and fixed macrophages; in the sinusoids of the liver, as Kupffer cells; in the lung, as alveolar macrophages; and in the nervous system, as microglia. Synonym: system of macrophages. (05 Mar 2000) |
| colloid system | A combination of the two phases, internal and external, of a colloid solution; the various system's are: gas + liquid (foam); gas + solid (meerschaum); liquid + gas (fog); solid + gas (smoke); solid + liquid (sol); liquid + solid (gel); liquid + liquid (emulsion); solid + solid (coloured glass). (05 Mar 2000) |
| pituitary-adrenal system | The interactions between the anterior pituitary and adrenal glands, in which corticotropin (acth) stimulates the adrenal cortex and adrenal cortical hormones suppress the production of corticotropin by the anterior pituitary. (12 Dec 1998) |
| combined system disease | A subacute or chronic disorder of the spinal cord, such as that occurring in certain patients with vitamin B12 deficiency, characterised by a slight to moderate degree of gliosis in association with spongiform degeneration of the posterior and lateral columns. Synonym: combined sclerosis, combined system disease, funicular myelitis, Putnam-Dana syndrome, vitamin B12 neuropathy. (05 Mar 2000) |