hair cycle

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Related to hair cycle: hair follicle, Telogen effluvium


a succession or recurring series of events.
cardiac cycle a complete cardiac movement, or heart beat, including systole, diastole, and the intervening pause.
Cardiac cycle. From Applegate, 2000.
cell cycle the cycle of biochemical and morphological events occurring in a reproducing cell population; it consists of the S phase, occurring toward the end of interphase, in which DNA is synthesized; the G2 phase, a relatively quiescent period; the M phase, consisting of the four phases of mitosis; and the G1 phase of interphase, which lasts until the S phase of the next cycle.
citric acid cycle tricarboxylic acid cycle.
estrous cycle the recurring periods of estrus in adult females of most mammalian species and the correlated changes in the reproductive tract from one period to another.
hair cycle the successive phases of the production and then loss of hair, consisting of anagen, catagen, and telogen.
menstrual cycle see menstrual cycle.
ovarian cycle the sequence of physiologic changes in the ovary involved in ovulation; see also ovulation and reproduction.
reproductive cycle the cycle of physiologic changes in the reproductive organs, from the time of fertilization of the ovum through gestation and childbirth; see also reproduction.
sex cycle (sexual cycle)
1. the physiologic changes that recur regularly in the reproductive organs of nonpregnant female mammals.
2. the period of sexual reproduction in an organism that also reproduces asexually.
tricarboxylic acid cycle the cyclic metabolic mechanism by which the complete oxidation of the acetyl portion of acetyl-coenzyme A is effected; the process is the chief source of mammalian energy, during which carbon chains of sugars, fatty acids, and amino acids are metabolized to yield carbon dioxide, water, and high-energy phosphate bonds. Called also citric acid cycle, Krebs cycle, and TCA cycle.
 Central pathways of metabolism: How the body produces energy from the energy-containing nutrients using the tricarboxylic acid cycle. From Davis and Sherer, 1994.
urea cycle a cyclic series of reactions that produce urea; it is a major route for removal of the ammonia produced in the metabolism of amino acids in the liver and kidney.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

hair cy·cle

the cyclic phases of growth (anagen), regression (catagen), and quiescence (telogen) in the life of a hair.
Farlex Partner Medical Dictionary © Farlex 2012

hair cycle

The repetitive sequence of growth and rest affecting the production of the hair follicles. The growth phase is known as anagen and this varies in length in different sites. The scalp anagen may last for several years. The rest phase is called the telogen. After about three months of telogen the hair is shed and a new anagen starts. Between these is the brief catagen during which the base of the hair becomes club-shaped.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
Chmielowiec et al., "Gab1 and Mapk signaling are essential in the hair cycle and hair follicle stem cell quiescence," Cell Reports, vol.
We suggest that some unidentified functional factors in deer antler, such as IGF-1, may play a role in regulating the hair cycle and follicle cell proliferation in rodents.
All mammals have a hair cycle: growing, resting, and shedding of hairs.
However, the compound also sped the hair cycle through catagen and into anagen.
Angora mouse mutation: altered hair cycle, follicular dystrophy, phenotypic maintenance of skin grafts, and changes in keratin expression.
Bernard, "Melanocyte subpopulation turnover during the human hair cycle: An Immunohistochemical Study," Pigment Cell Research, vol.
The length of hair varies with each individual, which depends on the three-phase hair cycle; the growing phase, resting phase, and falling phase.
Foitzik, "In search of the "hair cycle clock": a guided tour," Differentiation, vol.
In addition to the keratin genes and keratin-associated protein genes, researchers also found several enzymes of amino acid biosynthesis, with implications in regulating primary hair growth and hair cycle.
This is because when you are pregnant the hair cycle is longer and so there is less shedding and your hair grows thicker.
Dermal papilla cells (DPCs), a group of specialized fibroblasts within the hair follicle bulb, have an essential function in the control of hair growth not only in the normal hair cycle but also in the pathogenesis of certain conditions, for example in androgenetic alopecia (Inui et al., 2003).
Ulrike Lichti of the National Cancer Institute in Bethesda, Md., finds these results "very interesting, because at the moment we know very little about endogenous signals that could control the hair cycle."