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an interval or division of time; the time for the regular recurrence of a phenomenon.
absolute refractory period the part of the refractory period from phase 0 to approximately −60 mV during phase 3; during this time it is impossible for the myocardium to respond with a propagated action potential, even with a strong stimulus. Called also effective refractory period.
blanking period a period of time during and after a pacemaker stimulus when the unstimulated chamber is insensitive to avoid sensing the electronic event in the stimulated chamber.
effective refractory period absolute refractory period.
ejection period the second phase of ventricular systole (0.21 to 0.30 sec), between the opening and closing of the semilunar valves, while the blood is discharged into the aorta and pulmonary artery. Called also sphygmic period.
gestation period see gestation period.
incubation period see incubation period.
isoelectric period the moment in muscular contraction when no deflection of the galvanometer is produced.
latent period a seemingly inactive period, as that between exposure to an infection and the onset of illness (incubation period) or that between the instant of stimulation and the beginning of response (latency, def. 2).
refractory period the period of depolarization and repolarization of the cell membrane after excitation; during the first portion (absolute refractory period), the nerve or muscle fiber cannot respond to a second stimulus, whereas during the relative refractory period it can respond only to a strong stimulus.
relative refractory period the part of the refractory period from approximately −60 mV during phase 3 to the end of phase 3; during this time a depressed response to a strong stimulus is possible.
safe period the period during the menstrual cycle when conception is considered least likely to occur; it comprises approximately the ten days after menstruation begins and the ten days preceding menstruation. See the section on fertility awareness methods, under contraception.
sphygmic period ejection period.
supernormal period in electrocardiography, a period at the end of phase 3 of the action potential during which activation can be initiated with a milder stimulus than is required at maximal repolarization, because at this time the cell is excitable and closer to threshold than at maximal diastolic potential.
vulnerable period that time at the peak of the T wave during which serious arrhythmias are likely to result if a stimulus occurs.
in psychoanalytic personality theory, the period of psychosexual development in children, extending from about age 5 to the beginning of adolescence at age 12, during which the apparent cessation of sexual preoccupation stems from a strong, aggressive blockade of libidinal and sexual impulses in an effort to avoid oedipal relationships; during this phase, boys and girls are inclined to choose friends and join groups of their own sex.
Synonym(s): latency period
1. The fourth stage of psychosexual development in psychoanalytic theory, from about five years to puberty, during which a child apparently represses sexual urges and prefers to associate with members of the same sex. It is preceded by the phallic stage and followed by the genital stage.
2. A latent period.
Etymology: L, latere, to be concealed; Gk, peri + hodos, way
latency periodEpidemiology A period of subclinical or inapparent pathologic changes following exposure to a noxious agent, ending with the onset of Sx of disease. Cf Incubation period Psychology See Psychosexual development Virology
1. A period in which a virus–eg, EBV, HSV, HIV present in the body is undetectable or asymptomatic; viral LPs are attributed to a lack in host factors critical for expressing early viral gene products; during latency the virus absconds itself in certain cells–eg, EBV in epithelial cells and B lymphocytes; activation of specific cellular–host transcription factors in response to extracellular stimuli may induce the expression of viral regulatory proteins. leading to a burst of lytic viral replication.
2. The period that follows the 1º infection–chickenpox in Pts infected with varicella-zoster virus. See Herpes zoster.
la·ten·cy phase, latency period (lā'tĕn-sē fāz, pēr'ē-ŏd)
1. psychiatry According to psychoanalytic personality theory, the period of psychosexual development in children, extending from about age 5 to the beginning of adolescence around age 12, during which the apparent cessation of sexual preoccupation stems from a strong, aggressive blockade of libidinal and sexual impulses in an effort to avoid oedipal relationships; during this phase, boys and girls are inclined to choose friends and join groups of their own sex.
2. biowarfare Interval during which an organism lies dormant.