| endothelium derived relaxation factor | <biochemistry> This compound is produced from L arginine by the enzyme nitric oxide synthase. Acts as a potent vasorelaxant via elevation of intracellular cGMP in vascular smooth muscle. Synthesis of nitric oxide is not confined to endothelium, isoforms of nitric oxide synthase are also found in brain, neutrophils and platelets. Synonym: endothelium derived relaxation factor. Acronym: NO (29 Dec 1997) |
|---|---|
| transverse relaxation | In nuclear magnetic resonance, the rapid decay of the nuclear magnetization vector at right angles to the magnetic field after the 90 |
| longitudinal relaxation | In nuclear magnetic resonance, the return of the magnetic dipoles of the hydrogen nuclei (magnetization vector) to equilibrium parallel to the magnetic field, after they have been flipped 90 |
| activated clotting time | The most common test used for coagulation time in cardiovascular surgery. (05 Mar 2000) |
| activated partial thromboplastin time | The time needed for plasma to form a fibrin clot following the addition of calcium and a phospholipid reagent; used to evaluate the intrinsic clotting system. (05 Mar 2000) |
| A-H conduction time | Forward conduction of the cardiac impulse from atria to ventricles via the A-V node or any bypass tract, represented in the electrocardiogram by the P-R interval. P-H conduction time is from the onset of the P wave to the first high frequency component of the His bundle electrogram (normally 119 ± 38 msec); A-H conduction time is from the onset of the first high frequency component of the atrial electrogram to the first high frequency component of the His bundle electrogram (normally 92 ± 38 msec); P-A conduction time is from the onset of the P wave to the onset of the atrial electrogram (normally 27 ± 18 msec). (05 Mar 2000) |
| association time | Time elasping between a stimulus and the verbalised response to it. (05 Mar 2000) |
| biologic time | The concept that our appreciation of time varies with age and is governed by the neural organization of the individual; it obeys a logarithmic rather than an arithmetic law. (05 Mar 2000) |
| bleeding time | <haematology> A test which measures the time it takes for small blood vessels to close off and bleeding to stop. Abnormal results can be seen in those with congenital or acquired platelet function disorders or thrombocytopenia. (27 Sep 1997) |
| blood circulation time | Determination of the shortest time interval between the injection of a substance in the vein and its arrival at some distant site in sufficient concentration to produce a recognizable end result. It represents approximately the inverse of the average velocity of blood flow between two points. (12 Dec 1998) |
| P-A conduction time | See: atrioventricular conduction. (05 Mar 2000) |
| generation time | <cell biology> Time taken for a cell population to double in numbers and thus equivalent to the average length of the cell cycle. (18 Nov 1997) |
| reaction time | The time from the onset of a stimulus until the organism responds. (12 Dec 1998) |
| real-time ultrasonography | Rapid serial ultrasound images produced using a phased array or scanning transducer; produces a video display of organ motion, such as heart valve or foetal motion. (05 Mar 2000) |
| recognition time | The interval between the application of a stimulus and the recognition of its nature. (05 Mar 2000) |