| PHM | peptide histidine methionine; peptidylglycine alpha-hydroxylating monooxygenase; posterior hyaloid m... |
|---|---|
| PM | after death (Lat. post mortem); after noon [Lat. post meridiem]; mean pressure; pacemaker; pantomogr... |
| SM | Master of Science; sadomasochism; self-monitoring; silicon microphysiometer; simple mastectomy; skim... |
| TBM | total body mass; tracheobronchiomegaly; trophoblastic basement membrane; tuberculous meningitis; tub... |
| TM | technology management; tectorial membrane; temperature by mouth; temporalis muscle; temporomandibula... |
| Nernst potential | See: Nernst equation and ion selective electrodes. (18 Nov 1997) |
|---|---|
| surface potential | <cell biology, physiology> The electrostatic potential due to surface charged groups and adsorbed ions at a surface. It is usually measured as the zeta potential at the Helmholtz slipping plane outside the surface. (19 Jan 1998) |
| demarcation potential | The difference in potential recorded when one electrode is placed on intact nerve fibres or muscle fibres and the other electrode is placed on the injured ends of the same fibres; the intact portion is positive with reference to the injured portion. Synonym: injury potential. (05 Mar 2000) |
| diffusion potential | Potential arising from different rates of diffusion of ions at the interface of two dissimilar fluids, a junction potential. (18 Nov 1997) |
| inhibitory junction potential | Hyperpolarization of smooth muscle produced by stimulation of inhibitory nerves. (05 Mar 2000) |
| inhibitory postsynaptic potential | The change in potential produced in the membrane of the next neuron when an impulse which has an inhibitory influence arrives at the synapse; it is a local change in the direction of hyperpolarization; the frequency of discharge of a given neuron is determined by the extent to which impulses that lead to excitatory postsynaptic potential's predominate over those that cause inhibitory postsynaptic potential's. (05 Mar 2000) |
| injury potential | The difference in potential recorded when one electrode is placed on intact nerve fibres or muscle fibres and the other electrode is placed on the injured ends of the same fibres; the intact portion is positive with reference to the injured portion. Synonym: injury potential. (05 Mar 2000) |
| integrated biological hazard potential | <radiobiology> Total biological hazard potential of a collection of radioactive materials summed over their decay lifetimes. One measure of the integrated biological hazard potential is the amount of water one would need to use to dilute the materials to the point where the water would be safe to drink. (09 Oct 1997) |
| oscillatory potential | The variable voltage in the positive deflection of the electroretinogram (B-wave) of the dark-adapted eye arising from amacrine cells. (05 Mar 2000) |
| Ottoson potential | <investigation> An electronegative wave of potential occurring on the surface of the olfactory epithelium in response to stimulation by an odour. Synonym: osmogram, Ottoson potential. (05 Mar 2000) |
| oxidation-reduction potential | <chemistry, physics> The potential in volts of an inert metallic electrode measured in a system of an arbitrarily chosen ratio of [oxidant] to [reductant] and referred to the normal hydrogen electrode at absolute temperature. It is calculated from the following equation: where R is the gas constant expressed in electrical units, T the absolute temperature (Kelvin), n the number of electrons transferred, F the faraday and E0 the normal symbol for the potential of the system at pH 0; for biological systems E0' is often used (in which pH = 7). Compare: Nernst's equation. Synonym: redox potential. (05 Mar 2000) |
| thermodynamic potential | See: free energy. (05 Mar 2000) |
| early receptor potential | A voltage arising across the eye from a charge displacement within photoreceptor pigment, in response to an intense flash of light. (05 Mar 2000) |
| electrochemical potential | <chemistry> Defined as the work done in bringing 1 mole of an ion from a standard state (infinitely separated) to a specified concentration and electrical potential. Measured in joules/mole. More commonly used to measure the electrochemical potential difference between two points (e.g. Either side of a cell membrane), thus sidestepping the rather abstract concept of a standard state. If the molecule is uncharged or the electrical potential difference between two points is zero, the electrochemical potential reduces to the chemical potential difference of the species. at equilibrium, the electrochemical potential difference (by definition) is zero, the situation can then be described by the Nernst equation. (18 Nov 1997) |
| electronic potential | <chemistry, physiology> The measure (in volts) of electron pressure. A measure of the difference in electron concentrations between two compartments, such as either side of a cell membrane. (09 Oct 1997) |