| H+ | hydrogen ion |
|---|---|
| [H+] | hydrogen ion concentration |
| HEIS | high-energy ion scattering |
| ICM | inner cell mass; integrated conditional model; intercostal margin; International Confederation of Mi... |
| ICR | [distance between] iliac crests; Institute for Cancer Research; Institute for Cancer Research [mouse... |
| ion pumps | Integral membrane proteins that transport ions across a membrane against an electrochemical gradient. (12 Dec 1998) |
|---|---|
| ion selective electrode | An electrode half cell, with a semi permeable membrane that is permeable only to a single ion. The electrical potential measured between this and a reference half cell (e.g. A calomel electrode) is thus the Nernst potential for the ion. Given that the solution filling the ion selective electrode is known, the activity (rather than concentration) of the ion in the unknown solution can be measured. Commercial ion selective electrodes frequently use a hydrophobic membrane containing an ionophore, such as valinomycin (for potassium) or monensin (for sodium). A pH electrode is made with a thin membrane of pH sensitive (i.e. Proton permeable) glass. (18 Nov 1997) |
| ion-selective electrodes | Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions. (12 Dec 1998) |
| oxonium ion | <chemistry> A positively charged ion that is water with an additional hydrogen atom (H3O). (09 Oct 1997) |
| tetraethylammonium ion | A monovalent cation widely used in neurophysiology as a specific blocker of potassium channels. It is similar in size to the hydrated potassium ion and gets stuck (reversibly) in the channels. (18 Nov 1997) |
| field ion microscope | <instrument> Type of microscopy in which the specimen is illuminated with ions, often gallium ions, that are focussed electrostatically. The ions remove components of the specimen, lower atomic masses first. These are imaged and provide information on elemental distribution with a resolution of perhaps 30 nm. (18 Nov 1997) |
| ligand gated ion channel | A transmembrane ion channel whose permeability is increased by the binding of a specific ligand, typically a neurotransmitter at a chemical synapse. The permeability change is often drastic, such channels let through effectively no ions when shut, but allow passage at up to 10exp7 ions sexp 1 when a ligand is bound. Recently, the receptors for both acetylcholine and GABA have been found to share considerable sequence homology, implying that there may be a family of structurally related ligand gated ion channels. (18 Nov 1997) |
| light-ion fusion | <radiobiology> Light-Ion-Beam-Driven Inertial Confinement fusion, using beams of light ions driven at implosion targets. Pulsed-power driven accelerators are relatively efficient and cost-effective, but beam-focusing is a technical hurdle for this approach. (09 Oct 1997) |
| active transport | <biochemistry, chemistry> Transport of ions, nutrients or other molecules into a cell against a concentration gradient, this requires the expenditure of energy through ATP hydrolysis. (06 May 1997) |
| anterograde transport | Movement of material from the cell body of a neuron into axons and dendrites retrograde axoplasmic transport also occurs). (18 Nov 1997) |
| atrial transport function | The role of the atria in filling and stretching the ventricles by their presystolic contraction, without which the force of ventricular contraction and hence the cardiac output may significantly decrease. (05 Mar 2000) |
| axonal transport | Directed transport of organelles and molecules along a nerve cell axon. Transport can be anterograde (from the cell body) or retrograde (toward the cell body). (alberts et al., molecular biology of the cell, 3d ed, pg3) (12 Dec 1998) |
| axoplasmic transport | Transport by way of flow of axoplasm toward cell soma (retrograde) or toward axon terminal (anterograde). (05 Mar 2000) |
| biological transport | The movement of materials (including biochemical substances and drugs) across cell membranes and epithelial layers, usually by passive diffusion. (12 Dec 1998) |
| biological transport, active | The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy. (12 Dec 1998) |