| ion pump | A membranal complex of proteins that is capable of transporting ions against a concentration gradient using the energy from ATP. (05 Mar 2000) |
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| electrogenic pump | <physiology> Ion pump that generates net charge flow as a result of its activity. The sodium potassium exchange pump transports two potassium ions inward across the cell membrane for each three sodiums transported outward. This produces a net outward current that contributes to the internal negativity of the cell. (05 Jan 1998) |
| jet ejector pump | A suction pump in which fluid under high pressure is forced through a nozzle into an abruptly larger tube where a high velocity jet, at a low pressure in accordance with Bernoulli's law, entrains gas or liquid from a side tube opening just beyond the end of the nozzle to create suction; e.g., the pump by which steam is used to evacuate an autoclave, a water aspirator. (05 Mar 2000) |
| force pump | <machinery> A pump having a solid piston, or plunger, for drawing and forcing a liquid, as water, through the valves; in distinction from a pump having a bucket, or valved piston. A pump adapted for delivering water at a considerable height above the pump, or under a considerable pressure; in distinction from one which lifts the water only to the top of the pump or delivers it through a spout. Source: Websters Dictionary (01 Mar 1998) |
| acid dissociation constant | <chemistry> This is the equilibrium constant for the breaking apart of a weak acid into its hydrogen and conjugate base in a water solution. (09 Oct 1997) |
| Ambard's constant | <physiology> Obsolete law's for output of urea: 1. With the urinary urea concentration constant, urea output varies directly as the square of the concentration of the blood urea. 2. With the blood urea concentration constant, urea output varies inversely as the square root of its urinary concentration. (05 Mar 2000) |
| association constant | <chemistry> Reciprocal of dissociation constant. A measure of the extent of a reversible association between two molecular species at equilibrium. (18 Nov 1997) |
| Avogadro's constant | <physics> The number of molecules in a mole (gram molecular weight) of a substance, equals 6.02 x 1023 molecules. (09 Oct 1997) |
| base dissociation constant | <chemistry> This is the equilibrium constant for the reaction in which a weak base breaks apart in water to form its conjugate acid and hydroxide ion. (09 Oct 1997) |
| binding constant | <chemistry> Reciprocal of dissociation constant. A measure of the extent of a reversible association between two molecular species at equilibrium. (18 Nov 1997) |
| boltzmann constant | <radiobiology> K = 1.38 x 10^-16 erg/degree. This is the ratio of the universal gas constant to Avogadro's number. It is also used to relate temperatures (Kelvin) to energies (ergs or Joules) via E = (constant of order unity) kT. (09 Oct 1997) |
| radioactive constant | <physics, radiobiology> The fraction of the amount of a radionuclide that undergoes transition per unit time. Formally: Lamda=dP/dt Where dP is the probability of a given nucleus undergoing spontaneous nuclear transition in the time interval dt. (16 Dec 1997) |
| gas constant | R (symbol for the constant) = 8.314 × 107 ergs per degree Celsius per mole = 8.314 J K-1 mol-1 (joules per kelvin mole). (05 Mar 2000) |
| permeability constant | A measure of the ease with which an ion can cross a unit area of membrane driven by a 1.0 m difference in concentration; usually expressed in centimeters per second. Compare: permeability coefficient. (05 Mar 2000) |
| Michaelis constant | <chemistry> The true dissociation constant for the enzyme-substrate binary complex in a single-substrate rapid equilibrium enzyme-catalyzed reaction (usually symbolised by Ks), the concentration of the substrate at which half the true maximum velocity of an enzyme-catalyzed reaction is achieved (when velocities are measured under initial rate and steady state conditions). The ratio of rate constants (k2 + k3)/k1 in the single-substrate enzyme-catalyzed reaction: E + S &dblarr; ES &dblarr; E + products where E represents the free enzyme, S is the substrate, and ES is the central binary complex. The expression for the Michaelis constant will be more complex for multisubstrate reactions. An apparent Michaelis constant is a constant determined either under conditions that are not strictly steady state and initial rate or one that varies with the concentration of one or more cosubstrates. See: Michaelis-Menten equation. Synonym: Michaelis-Menten constant. (05 Mar 2000) |