| cardiac gating | Using an electronic signal from the cardiac cycle to trigger an event, such as in imaging separate phases of cardiac contraction. (05 Mar 2000) |
|---|---|
| gating | 1. In a biological membrane, the opening and closing of a channel, believed to be associated with changes in integral membrane proteins. 2. A process in which electrical signals are selected by a gate, which passes such signals only when the gate pulse is present to act as a control signal, or passes only the signals that have certain characteristics. See: gate. (05 Mar 2000) |
| gating current | <physiology> Small currents in the membrane just prior to the increase in ionic permeability, due to the movement of charged particles within the membrane. So called because they open the gates for current flow through ion channels. (20 Mar 1998) |
| gating mechanism | Occurrence of the maximum refractory period among cardiac conducting cells approximately 2 mm proximal to the terminal Purkinje fibres in the ventricular muscle, beyond which the refractory period is shortened through a sequence of Purkinje cells, transitional cells, and muscular cells; gating mechanism may be a cause of ventricular aberration, bidirectional tachycardia, and concealed extrasystoles, a mechanism by which painful impulses may be blocked from entering the spinal cord. Compare: gate-control theory. (05 Mar 2000) |
| channel gating | <physiology> Small currents in the membrane just prior to the increase in ionic permeability, due to the movement of charged particles within the membrane. So called because they open the gates for current flow through ion channels. (20 Mar 1998) |
| ion channel gating | The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability. (12 Dec 1998) |
| catheterization, peripheral | Insertion of a catheter into a peripheral artery, vein, or airway for diagnostic or therapeutic purposes. (12 Dec 1998) |
| peripheral | <anatomy> Pertaining to or situated at or near the periphery, situated away from a centre or central structure. (18 Nov 1997) |
| peripheral aneurysm | A saclike aneurysm springing from one side of an artery, an aneurysm of one of the smaller branches of an artery. (05 Mar 2000) |
| peripheral anterior synechia | Adhesion of the iris to the posterior surface of the cornea in the angle of the anterior chamber; associated with angle-closure glaucoma. Synonym: peripheral anterior synechia. Origin: G. Gonia, angle, + synechis, holding together (05 Mar 2000) |
| peripheral arteriosclerosis | Arteriosclerosis in any of the vessels beyond the aorta; most often refers to the lower extremities. (05 Mar 2000) |
| peripheral blood stem cell transplantation | A procedure that is similar to bone marrow transplantation. Doctors remove healthy immature cells (stem cells) from a patient's blood and store them before the patient receives high-dose chemotherapy and possibly radiation therapy to destroy the leukaemia cells. The stem cells are then returned to the patient, where they can produce new blood cells to replace cells destroyed by the treatment. (12 Dec 1998) |
| peripheral cataract | A cataract in which the opacity affects the cortex of the lens. Synonym: peripheral cataract. (05 Mar 2000) |
| peripheral chemoreceptor | The chemoreceptor's in the carotid and aortic bodies that are stimulated by chemical changes in the composition of the blood such as hypoxia. (05 Mar 2000) |
| peripheral dysostosis | Dysostosis of the metacarpals and metatarsals, accompanied by variable facial features; possibly autosomal dominant inheritance. (05 Mar 2000) |