| 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) |
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| 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) |
| missed period | The failure of menstruation to occur in any month at the expected time. (05 Mar 2000) |
| mitotic period | The period of the cell cycle in which all phases of mitosis occur. Synonym: M phase. (05 Mar 2000) |
| Wenckebach period | A sequence of cardiac cycles in the electrocardiogram ending in a dropped beat due to A-V block, the preceding cycles showing progressively lengthening P-R intervals; the P-R interval following the dropped beat is again shortened. (05 Mar 2000) |
| crisis period | A situation in which most of the secondary cells in a culture die off, even though conditions exist which should normally be favorable for their growth. (09 Oct 1997) |
| critical period | <psychology> A specific stage in animal and human development during which certain types of behaviour normally are shaped and molded for life. (12 Dec 1998) |
| postoperative period | The period following a surgical operation. (12 Dec 1998) |