| resting potential | <physiology> The electrical potential of the inside of a cell, relative to its surroundings. Almost all animal cells are negative inside, resting potentials are in the range 20 to 100mV, 70mV typical. Resting potentials reflect the action of the sodium pump only indirectly, they are mainly caused by the subsequent diffusion of potassium out of the cell through potassium leak channels. The resting potential is thus close to the Nernst potential for potassium. See: action potential. (10 Mar 1998) |
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| membrane potential | <physiology> More correctly, transmembrane potential difference: the electrical potential difference across a plasma membrane. See: resting potential, action potential. (18 Nov 1997) |
| chemical potential | <chemistry> The work required (in j mol 1) to bring a molecule from a standard state (usually infinitely separated in a vacuum) to a specified concentration. More usually employed as chemical potential difference, the work required to bring one mole of a substance from a solution at one concentration to another at a different concentration, __ = RT.In (c2/cl). This definition is useful in studies of active transport, note that, for charged molecules, the electrical potential difference must also be considered (see electrochemical potential). (18 Nov 1997) |
| miniature end plate potential | <physiology> Small fluctuations (typically 0.5 mV) in the resting potential of postsynaptic cells. They are the same shape as, but much smaller than, the end plate potentials caused by stimulation of the presynaptic cell. Miniature end plate potentials are considered as evidence for the quantal release of neurotransmitters at chemical synapses, a single miniature end plate potential resulting from the release of the contents of a single synaptic vesicle. (12 Jan 1998) |
| water potential | <plant biology> The chemical potential (i.e. Free energy per mole) of water in plants. Water moves within plants from regions of high water potential to regions of lower water potential, i.e. Down gradient. (18 Nov 1997) |
| myogenic potential | Action potential of muscle. (05 Mar 2000) |
| postsynaptic potential | In a synapse, a change in the resting potential of a postsynaptic cell following stimulation of the presynaptic cell. For example: in a cholinergic synapse, the release of acetylcholine from the presynaptic cell causes channels to open in the postsynaptic cell. Each channel opening causes a small depolarisation, known as a miniature end plate potential (mepp), these sum to produce an excitatory postsynaptic potential. (18 Nov 1997) |
| potential | Existing and ready for action but not yet active. (18 Nov 1997) |
| potential energy | <chemistry> Energy due to position, it is stored energy which can be used to do work. (09 Jan 1998) |
| site potential tree | A tree that has attained the average maximum height possible given site conditions where it occurs. (05 Dec 1998) |
| somatosensory evoked potential | The computer-averaged cortical and subcortical responses to repetitive stimulation of peripheral nerve sensory fibres. (05 Mar 2000) |
| spike potential | The main wave in the action potential of a nerve; it is followed by negative and positive afterpotentials. (05 Mar 2000) |
| S potential | Prolonged, slow, depolarising or hyperpolarising responses to illumination; initiated between the photoreceptor and ganglion cell layers of the retina. (05 Mar 2000) |
| 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) |