| tight junction | <cell biology> Specialised intercellular junction in which the two plasma membranes are separated by only 1-2nm. Found near the apical surface of cells in simple epithelia, forms a sealing gasket around the cell. Prevents fluid moving through the intercellular gap and the lateral diffusion of intrinsic membrane proteins between apical and baso lateral domains of the plasma membrane. (18 Nov 1997) |
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| 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) |
| 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) |