| POSM | patient-operated selector mechanism |
|---|---|
| SAM | S-adenosyl-L-methionine; scanning acoustic microscope; senescence accelerated mouse; sex arousal mec... |
| TM | technology management; tectorial membrane; temperature by mouth; temporalis muscle; temporomandibula... |
| ping-pong mechanism | A special multisubstrate reaction in which, for a two-substrate, two-product (i.e., bi-bi) system, an enzyme reacts with one substrate to form a product and a modified enzyme, the latter then reacting with a second substrate to form a second, final product, and regenerating the original enzyme. An example of such a mechanism is found in the aminotransferases. More complex ping-pong mechanisms exist for enzymes having more than two substrates. Synonym: double displacement mechanism. (05 Mar 2000) |
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| countercurrent mechanism | A system in the renal medulla that facilitates concentration of the urine as it passes through the renal tubules. See: countercurrent exchanger, countercurrent multiplier. (05 Mar 2000) |
| pressoreceptive mechanism | The pressoreceptor system, especially of the carotid sinuses and aortic arch. (05 Mar 2000) |
| proprioceptive mechanism | <physiology> The mechanism of sense of position and movement, by which muscular movements can be adjusted to a great degree of accuracy and equilibrium maintained. (05 Mar 2000) |
| Schultze's mechanism | Expulsion of the placenta with the foetal surface foremost. (05 Mar 2000) |
| defense mechanism | A psychological means of coping with conflict or anxiety, e.g., conversion, denial, dissociation, rationalization, repression, sublimation, the psychic structure underlying a coping strategy, immunological mechanism vs. Non-specific defense mechanism. (05 Mar 2000) |
| double displacement mechanism | A special multisubstrate reaction in which, for a two-substrate, two-product (i.e., bi-bi) system, an enzyme reacts with one substrate to form a product and a modified enzyme, the latter then reacting with a second substrate to form a second, final product, and regenerating the original enzyme. An example of such a mechanism is found in the aminotransferases. More complex ping-pong mechanisms exist for enzymes having more than two substrates. Synonym: double displacement mechanism. (05 Mar 2000) |
| Duncan's mechanism | Passage of the placenta from the uterus with the rough side foremost. (05 Mar 2000) |
| immunological mechanism | The groups of cells (chiefly lymphocytes and cells of the reticuloendothelial system) that function in establishing active acquired immunity (induced sensitivity, allergy). (05 Mar 2000) |
| ordered mechanism | A scheme for substrate binding and product release for multisubstrate enzymes; for a two-substrate two-product enzyme with an ordered mechanism, one particular substrate has to bind to the enzyme first followed by the other substrate; chemistry then occurs, products are formed and are released from the enzyme in a distinct order. More complex ordered schemes exist for enzymes having more than two substrates. Some of the dehydrogenases have such a mechanism. Synonym: ordered. (05 Mar 2000) |
| ordered on-random off mechanism | A scheme for substrate binding and product release for multisubstrate enzymes; for a two-substrate two-product enzyme with this mechanism, the individuals have to bind to the enzyme in a distinct order; however, once the products are formed they may dissociate from the enzyme in either order. It has been suggested that pyruvate kinase has such a mechanism. The random on-ordered off mechanism is simply the reverse of this mechanism. (05 Mar 2000) |