| electrotonic junction | <cell biology> A junction between two cells consisting of many pores that allow the passage of molecules up to about 900D. Each pore is formed by an hexagonal array (connexon) of six transmembrane proteins (connexins) in each plasma membrane: when mated together the pores open, allowing communication and the interchange of metabolites between cells. Electrical synapses are gap junctions and metabolic cooperation depends upon the formation of gap junctions. (18 Nov 1997) |
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| excitatory junction potential | Discrete partial depolarisation of smooth muscle produced by stimulation of excitatory nerves; similar to small end-plate potentials. They summate with repeated stimuli. (05 Mar 2000) |
| tympanostapedial junction | The connection of the base or foot-plate of the stapes with the vestibular (oval) window. Synonym: syndesmosis tympanostapedia, tympanostapedial syndesmosis. (05 Mar 2000) |
| junction | 1. The act of joining, or the state of being joined; union; combination; coalition; as, the junction of two armies or detachments; the junction of paths. 2. The place or point of union, meeting, or junction; specifically, the place where two or more lines of railway meet or cross. Junction plate, the switch, or movable, rails, connecting one line of track with another. Origin: L. Junctio, fr. Jungere, junctum, to join: cf. F. Jonction. See Join. Source: Websters Dictionary (01 Mar 1998) |
| junction nevus | A nevus consisting of nests of melanocytes in the basal cell zone, at the junction of the epidermis and dermis, appearing as a slightly raised, small, flat, nonhairy pigmented (brown or black) tumour. Synonym: epidermic-dermic nevus. (05 Mar 2000) |
| junction of lips | The junction of the lips lateral to the angle of the mouth. Synonym: commissura labiorum, junction of lips. (05 Mar 2000) |
| junction potential | <physiology> Potential difference at the boundary between dissimilar solutions, arises from differences in diffusion constants between ions. (18 Nov 1997) |
| ureteropelvic junction | Site of origin of the ureter from the renal pelvis, a common location for congenital or acquired obstruction. (05 Mar 2000) |
| ureteropelvic junction obstruction | <urology> A blockage of a ureter in the region where the ureter enters the anatomic pelvis (close to the bladder). This is caused most often by a kidney stone but can also be caused by external (or internal) compression from a tumour. (27 Sep 1997) |
| agent | <pharmacology> Any power, principle or substance capable of producing an effect, whether physical, chemical or biological. Origin: L. Agens = acting (18 Nov 1997) |
| agent, antihypertensive | As the name suggests, a drug aimed at reducing high blood pressure (hypertension). (12 Dec 1998) |
| agent, anti-infective | Something capable of acting against infection, by inhibiting the spread of an infectious agent or by killing the infectious agent outright. (12 Dec 1998) |
| Agent Orange | An herbicide and defoliant, consisting of (2,4,5-trichlorophenoxy)acetic acid, (2,4-dichlorophenoxy)acetic acid, and dioxin, that was widely used in the Vietnam War; it has been shown to possess residual post-exposure carcinogenic and teratogenic properties in humans. (05 Mar 2000) |
| agent, tocolytic | A medication that can inhibit labour, slow down or halt the contractions of the uterus. Tocolytic agents are widely used today to treat premature labour and permit pregnancy to procede and so let the foetus gain in size and maturity before being born. (12 Dec 1998) |
| alkylating agent | <oncology, pharmacology> A reagent that places an alkyl group, for example propyl in place of a nucleophilic group in a molecule. Alkylating reagents include a number of cytotoxic drugs some of which react fairly specifically with N7 of the purine ring and lead to depurination of DNA, for example the agent ethyl ethanesulphonic acid and thus to mutagenesis. The drugs interaction with DNAand prevents the division of the cells. Examples of drugs include: busulphan, chlorambucil, cyclophosphamide, melphalan. (29 Sep 1997) |