| tachycardia, paroxysmal atrial | Bouts of rapid, regular heart beating originating in the atrium (upper chamber of the heart). Often due to abnormalities in the av node relay station that lead to rapid firing of electrical impulses from the atrium which bypass the av node under certain conditions. These conditions include alcohol excess, stress, caffeine, overactive thyroid or excessive thyroid hormone intake, and certain drugs. Pat is an example of an arrhythmia where the abnormality is in the electrical system of the heart, while the heart muscle and valves may be normal. (12 Dec 1998) |
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| familial paroxysmal rhabdomyolysis | acute recurrent rhabdomyolysis |
| absolute refractory period | The period following excitation when no response is possible regardless of the intensity of the stimulus. (05 Mar 2000) |
| alabama period | <geology> A period in the American eocene, the lowest in the tertiary age except the lignitic. Source: Websters Dictionary (01 Mar 1998) |
| anaesthesia recovery period | The period of emergence from general anaesthesia, where different elements of consciousness return at different rates. (12 Dec 1998) |
| Gap1 period | The period of the cell cycle after cell division when there is synthesis of RNA and protein; it may last for a few hours in rapidly growing tissue or a lifetime in non-renewing cells such as nerve cells. Synonym: Gap1 phase, postmitotic phase. (05 Mar 2000) |
| Gap2 period | The period in the cell cycle when synthesis of DNA is completed but before mitosis begins. Synonym: Gap2 phase, premitotic phase. (05 Mar 2000) |
| masticatory silent period | A pause in electromyographic patterns associated with tooth contacts during chewing and biting; a part of the complex feedback mechanism of mandibular control involving receptors in the periodontal ligament and muscles. (05 Mar 2000) |
| refractory period | <neurology, physiology> most commonly used in reference to the interval (typically 1ms) after the passage of an action potential during which an axon is incapable of responding to another. This is caused by inactivation of the sodium channels after opening. The maximum frequency at which neurons can fire is thus limited to a few hundred Hertz. An analogous refractory period occurs in individuals of Dictyostelium discoideum, which are insensitive to extracellular cyclic AMP immediately after a pulse of cAMP has been secreted. The term can be applied to any system where a similar insensitive period follows stimulation. (18 Nov 1997) |
| refractory period of electronic pacemaker | The time required to restore full sensitivity after detecting cardiac activity or delivering a pacing impulse. (05 Mar 2000) |
| refractory period, psychological | A delayed response interval occurring when two stimuli are presented in close succession. (12 Dec 1998) |
| relative refractory period | The period between the effective refractory period and the end of the refractory period; fibres then respond only to high intensity stimuli and the impulses conduct more slowly than normally. (05 Mar 2000) |
| vulnerable period | Vulnerable period of heart, a brief time during the cardiac cycle when stimuli are particularly likely to induce repetitive activity like tachycardia, flutter, or fibrillation which persists after the stimulus has ceased; for the ventricle, it occurs during the latter part of systole, during the relative refractory period coincident with the inscription of the latter half of the T wave of the electrocardiogram. (05 Mar 2000) |
| menstrual period | <medicine> The catamenial or menstrual discharge, a periodic flow of blood or bloody fluid from the uterus or female generative organs. Origin: L. Mensis month, pl. Menses months, and the monthly courses of women. Cf. Month. Source: Websters Dictionary (01 Mar 1998) |
| period | Drosophila gene regulating circadian rhythm. See: timeless. (18 Nov 1997) |