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Encyclopedia > Ovulation cycle
Menstrual cycle......
Menstrual cycle......

The menstrual cycle is a recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility. Download high resolution version (947x1191, 47 KB) Created by Chris 73. ... Download high resolution version (947x1191, 47 KB) Created by Chris 73. ... Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. ...


This article concentrates on the menstrual cycle as it occurs in human beings. Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ...

Contents


Overview

Only human beings and the great apes experience a true menstrual cycle. Most placental mammals experience estrus instead. The menstrual cycle is under the control of the reproductive hormone system and is necessary for reproduction. In women, menstrual cycles occur typically on a monthly basis between puberty and menopause. Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Genera Subfamily Ponginae Pongo - Orangutans Gigantopithecus (extinct) Sivapithecus (extinct) Subfamily Homininae Gorilla - Gorillas Pan - Chimpanzees Homo - Humans Paranthropus (extinct) Australopithecus (extinct) Sahelanthropus (extinct) Ardipithecus (extinct) Kenyanthropus (extinct) Pierolapithecus (extinct) (tentative) The Hominids (Hominidae) are a biological family which includes humans, extinct species of humanlike creatures and the other great apes... The placenta is an ephemeral and temporary organ present only in female placental mammals during gestation (pregnancy). ... Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... Estrus (also spelled œstrus) or heat in female mammals is the period of greatest female sexual responsiveness usually coinciding with ovulation. ... For other uses, see Reproduction (disambiguation) Reproduction is the biological process by which new individual organisms are produced. ... A hormone (from Greek horman - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... For other uses, see Reproduction (disambiguation) Reproduction is the biological process by which new individual organisms are produced. ... Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ... Menopause (also known as the Change of life or climacteric) is a stage of the human female reproductive cycle that occurs as the ovaries stop producing estrogen, causing the reproductive system to gradually shut down. ...


During the menstrual cycle, the sexually mature female body releases one egg (or occasionally two, which might result in dizygotic, or non-identical, twins) at the time of ovulation. The lining of the uterus, the endometrium, builds up in a synchronised fashion. After ovulation, this lining changes to prepare for potential implantation of the fertilized egg to establish a pregnancy. If fertilization and pregnancy do not ensue, the uterus sheds the lining and a new menstrual cycle begins. The process of the shedding of the lining is called menstruation. Menstruation manifests itself to the outer world in the form of the menses (also menstruum): essentially part of the endometrium and blood products that pass out of the body through the vagina. Although this is commonly referred to as blood, it differs in composition from venous blood. A human ovum An ovum (from Latin, loosely, egg or egg cell) is a female sex cell or gamete. ... This article or section does not cite its references or sources. ... Fraternal twin boys in the tub The term twin most notably refers to two individuals (or one of two individuals) who have shared the same uterus (womb) and usually, but not necessarily, born on the same day. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ... Female internal reproductive anatomy The uterus or womb is the major female reproductive organ of most mammals, including humans. ... The endometrium is the inner uterine membrane in mammals which is developed in preparation for the implantation of a fertilized egg upon its arrival into the uterus. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ... Implantation occurs when a fertilized zygote attaches itself onto the lining of the uterus. ... Pregnancy Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies. ... Human female internal reproductive anatomy. ... In the circulatory system, venous blood is blood returning to the heart. ...


Common usage refers to menstruation and menses as a period. This bleeding serves as a sign that a woman has not become pregnant. (However, this cannot be taken as certainty, as sometimes there is some bleeding in early pregnancy.) During the reproductive years, failure to menstruate may provide the first indication to a woman that she may have become pregnant. A woman might say that her "period is late" when an expected menstruation has not started and she might have become pregnant. Pregnancy Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies. ... Image of a nude woman on the Pioneer plaque sent to outer space. ...


Menstruation forms a normal part of a natural cyclic process occurring in healthy women between puberty and the end of the reproductive years. The onset of menstruation, known as menarche, occurs at an average age of 12, but can occur any time between the ages of 8 and 16.[1] However, the condition precocious puberty has caused menstruation to occur in girls as young as 8 months old. The last period, menopause, usually occurs between the ages of 45 and 55. Deviations from this pattern deserve medical attention. Amenorrhea refers to a prolonged absence of menses during the reproductive years of a woman for reasons other than pregnancy. For example, women with very low body fat, such as athletes, may cease to menstruate. The presence of menstruation does not prove that ovulation took place; women who do not ovulate may have menstrual cycles. Those anovulatory cycles tend to take place less regularly and show greater variation in cycle length. In addition, the absence of menstruation also does not prove that ovulation did not take place, because hormone disruptions in non-pregnant women can suppress bleeding on occasion. Puberty refers to the process of physical changes by which a childs body becomes an adult body capable of reproduction. ... Menarche refers to the first menstrual period, or first menstrual bleeding, as a girls body progresses through the changes of puberty. ... Precocious puberty means early puberty. ... Menopause (also known as the Change of life or climacteric) is a stage of the human female reproductive cycle that occurs as the ovaries stop producing estrogen, causing the reproductive system to gradually shut down. ... Amenorrhoea (BE) or amenorrhea (AmE) is the absence of a menstrual period in a woman of reproductive age. ... In biochemistry, fat is a generic term for a class of lipids. ... An athlete is a person who has above average physical skills (strength, agility, and endurance) and is thus suitable for physical activities, in particular, contests. ... The anovulatory cycle is a menstrual cycle characterized by varying degrees of menstrual intervals and the absence of ovulation and a luteal phase. ...


The normal menstrual cycle in humans

Women show considerable variation in the lengths of their menstrual cycles, and the length of the menstrual cycle differs in different animals (see below).


While cycle length may vary, 28 days is generally taken as representative of the average ovulatory cycle in women. Convention uses the onset of menstrual bleeding to mark the beginning of the cycle, so the first day of bleeding is called "Cycle Day one".


One can divide the menstrual cycle into four phases:


Menstruation

Eumenorrhea denotes normal, regular menstruation that lasts for a few days (usually 3 to 5 days, but anywhere from 2 to 7 days is considered normal [2]). The average blood loss during menstruation is 35 millilitres with 10-80 mL considered normal[3]; many women also notice shed endometrium lining that appears as tissue mixed with the blood. An enzyme called plasmin — contained in the endometrium — inhibits the blood from clotting. Because of this blood loss, women have higher dietary requirements for iron than do males to prevent iron deficiency. Many women experience uterine cramps, also referred to as dysmenorrhea, during this time. A vast industry has grown to provide sanitary products to help women to manage their menses. (Redirected from 1 E-5 m3) To help compare different orders of magnitude this page lists volumes between 10-5 cubic metres and 10-4 cubic metres (10 cubic centimetres and 100 cubic centimetres). ... The endometrium is the inner uterine membrane in mammals which is developed in preparation for the implantation of a fertilized egg upon its arrival into the uterus. ... Ribbon diagram of the catalytically perfect enzyme TIM. An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. ... Plasmin is an important degrading enzyme (EC 3. ... Coagulation is the thickening or congealing of any liquid into solid clots. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... It has been suggested that this article or section be merged into iron deficiency anemia. ... Matrilineality is a system in which one belongs to ones mothers lineage; it may also involve the inheritance of property or titles through the female line. ... Dysmenorrhea (or dysmenorrhoea), cramps or painful menstruation, involves menstrual periods that are accompanied by either sharp, intermittent pain or dull, aching pain, usually in the pelvis or lower abdomen. ...


Follicular phase

Through the influence of a rise in Follicle stimulating hormone (FSH), five to seven tertiary-stage ovarian follicles are recruited for entry into the menstrual cycle. These follicles, that have been growing for the better part of a year in a process known as folliculogenesis, compete with each other for dominance. In a signal cascade kicked off by luteinizing hormone (LH), the follicles secrete estradiol, a steroid that acts to inhibit pituitary secretion of FSH. With diminished FSH supply comes a slowing in growth that eventually leads to follicle death, known as atresia. The largest follicle secretes inhibin that serves as a finishing blow to less competent follicles by further suppressing FSH. This dominant follicle continues growing, forms a bulge near the surface of the ovary, and soon becomes competent to ovulate. Follicle stimulating hormone (FSH) is a hormone produced by gonadotropes in the anterior pituitary gland. ... In biology, folliculogenesis refers to the maturation of the ovarian follicle, a densely-packed shell of somatic cells that contains an immature oocyte. ... Luteinizing hormone (LH) is a hormone synthesised and secreted by gonadotropes in the anterior lobe of the pituitary gland. ... Estradiol (17-beta estradiol) is a sex hormone. ... Inhibin is a peptide that is an inhibitor of FSH synthesis and secretion and participates in the regulation of the menstrual cycle. ...


The follicles also secrete estrogens (of which estradiol is a member). Estrogens initiate the formation of a new layer of endometrium in the uterus, histologically identified as the proliferative endometrium. If fertilised, the embryo will implant itself within this hospitable flesh. Estrogens (also oestrogens) are a group of steroid compounds, named for their importance in the oestrus cycle, functioning as the primary female sex hormone. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ...


Ovulation

This ovary is about to release an egg.
This ovary is about to release an egg.

When the follicle has matured, it secretes enough estradiol to trigger the acute release of luteinizing hormone (LH). In the average cycle this LH surge starts around cycle day 12 and may last 48 hours. The release of LH matures the egg and weakens the wall of the follicle in the ovary. This process leads to ovulation: the release of the now mature ovum, the largest cell of the body (with a diameter of about 0.5 mm). Which of the two ovaries — left or right — ovulates appears essentially random; no known left/right co-ordination exists. The Fallopian tube needs to capture the egg and provide the site for fertilisation. A characteristic clear and stringy mucus exhibiting spinnbarkeit develops at the cervix, ready to accept sperm from intercourse. In some women, ovulation features a characteristic pain called Mittelschmerz (German term meaning 'middle pain') which lasts for several hours. The sudden change in hormones at the time of ovulation also causes light mid-cycle bleeding for some women. Many women perceive the vaginal and cervical mucus changes at ovulation, particularly if they are monitoring themselves for signs of fertility. An unfertilised egg will eventually disintegrate or dissolve in the uterus. Scientific investigations[4] have indicated that the olfactory acuity or the sense of smell is greatest during ovulation in women. Download high resolution version (688x973, 276 KB)Impending Ovulation This is an ovary shortly before an egg is released. ... Download high resolution version (688x973, 276 KB)Impending Ovulation This is an ovary shortly before an egg is released. ... Luteinizing hormone (LH) is a hormone synthesised and secreted by gonadotropes in the anterior lobe of the pituitary gland. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ... A human ovum An ovum (from Latin, loosely, egg or egg cell) is a female sex cell or gamete. ... (Redirected from 1 E 4 m) To help compare different orders of magnitude this page lists lengths between 10 and 100 km (104 to 105 m). ... Female internal reproductive anatomy The Fallopian tubes or oviducts are two very fine tubes leading from the ovaries of female mammals into the uterus. ... A spermatozoon fertilising an ovum Fertilization (also known as conception, fecundation and syngamy) is fusion of gametes to form a new organism. ... Mucus is a slippery secretion of the lining of various membranes in the body (mucous membranes). ... Spinnbarkeit is a medical term and refers to the stringy and stretchy quality of cervical mucus at the time just prior to ovulation. ... Schematic frontal view of female anatomy The cervix (from Latin neck) is actually the lower, narrow portion of the uterus where it joins with the top end of the vagina. ... The signifier sperm can refer to: (mass noun, from Greek sperma = seed) a substance which consists of spermatozoa and which is a component of semen (mass noun) semen itself (informally, count noun with plural sperm or sperms) a single spermatozoon (= sperm cell) sperma ceti (Latin ceti, genitive of cetus = whale... The word intercourse refers to: Look up intercourse in Wiktionary, the free dictionary. ... Mittelschmerz (German: middle pain) is a medical term for ovulation pain. Some women have mittelschmerz regularly and can time their ovulation by it, but many never experience it. ... Fertility Awareness (FA) is the practice of observing one or more of a woman’s primary fertility signs to determine the fertile and infertile phases of her cycle. ... Olfaction, the sense of smell, is the detection of chemicals dissolved in air (or, by animals that breathe water, in water). ... Olfaction, the sense of odor (smell), is the detection of chemicals dissolved in air (or, by animals that breathe water, in water). ...


Luteal phase

The corpus luteum is the solid body formed in the ovaries after the egg has been released from the fallopian tube which continues to grow and divide for a while. After ovulation, the residual follicle transforms into the corpus luteum under the support of the pituitary hormones. This corpus luteum will produce progesterone in addition to estrogens for approximately the next 2 weeks. Progesterone plays a vital role in converting the proliferative endometrium into a secretory lining receptive for implantation and supportive of the early pregnancy. It raises the body temperature by half- to one degree Fahrenheit (one-quarter to one-half degree Celsius), thus women who record their temperature on a daily basis will notice that they have entered the luteal phase. If fertilisation of an egg has occurred, it will travel as an early embryo through the tube to the uterine cavity and implant itself 6 to 12 days after ovulation. Shortly after implantation, the growing embryo will signal its existence to the maternal system. One very early signal consists of human chorionic gonadotropin (hCG), a hormone that pregnancy tests can measure. This signal has an important role in maintaining the corpus luteum and enabling it to continue to produce progesterone. In the absence of a pregnancy and without hCG, the corpus luteum demises and inhibin and progesterone levels fall. This will set the stage for the next cycle. Progesterone withdrawal leads to menstrual shedding (progesterone withdrawal bleeding), and falling inhibin levels allow FSH levels to rise to raise a new crop of follicles. The corpus luteum (Latin for yellow body) is a small, temporary endocrine structure in mammals that develops from an ovarian follicle during the luteal phase of the menstrual cycle, following the release of a mature egg during ovulation. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ... Implantation occurs when a fertilized zygote attaches itself onto the lining of the uterus. ... Pregnancy Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies. ... Embryos (and one tadpole) of the wrinkled frog (Rana rugosa). ... Human chorionic gonadotropin (hCG) is a peptide hormone produced in pregnancy, that is made by the embryo soon after conception and later by the trophoblast (part of the placenta). ... HCG may stand for Human chorionic gonadotropin (usually abbreviated with a lowercase h: hCG) H computer graphics (pornographic drawings in H games) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... A pregnancy test is a test to determine whether or not a woman is pregnant. ...


Menstrual symptoms

In many women, various unpleasant symptoms caused by the involved hormones and by cramping of the uterus can precede or accompany menstruation. More severe symptoms may include significant menstrual pain (dysmenorrhea), abdominal pain, migraine headaches, depression and irritability. Some women encounter premenstrual stress syndrome (PMS or premenstrual syndrome), a cyclic clinical entity. Other women are said to suffer from what some doctors call post-menstrual syndrome where similar symptoms manifest themseleves. This is rare and is usually not as severe or as long as pre-menstrual syndrome. Breast discomfort caused by premenstrual water retention is very common. The list of symptoms experienced varies from person to person. Furthermore, within an individual, the severity of the symptoms may vary from cycle to cycle. Pharmaceutical and herbal companies provide products designed to lessen or relieve some or all of these symptoms. This article is about muscular pain. ... Dysmenorrhea (or dysmenorrhoea), cramps or painful menstruation, involves menstrual periods that are accompanied by either sharp, intermittent pain or dull, aching pain, usually in the pelvis or lower abdomen. ... Sad redirects here; for the three letter acronym, see SAD, or for the Quranic sura see Sad Depression, or, more properly, a depressed mood, refers to a state of non-clinical melancholia that is shorter than 2 weeks in duration and distinctly differentiated from a diagnosis of clinical depression. ... Premenstrual Stress Syndrome (PMS, also called Premenstrual Stress, Premenstrual Tension, PMT, Premenstrual Syndrome, Periodic Mood Swing) is stress which is a physical symptom prior to the onset of menstruation. ... Premenstrual water retention is a common phenomenon associated with the menstrual cycle. ...


The fertile window

The length of the follicular phase — and consequently the length of the menstrual cycle — may vary widely. The luteal phase, however, almost always takes the same number of days. Some women have a luteal phase of 10 days, others of 16 days (the average is 14 days), but for each individual woman, this length will remain constant. Sperm survive inside a woman for 3 days on average, with survival time up to five days considered normal. A pregnancy resulting from sperm life of eight days has been documented [5]. The most fertile period (the time with the highest likelihood of sexual intercourse leading to pregnancy) covers the time from some 5 days before ovulation until 1-2 days after ovulation. In an average 28 day cycle with a 14-day luteal phase, this corresponds to the second and the beginning of the third week of the cycle. Fertility awareness methods of birth control attempt to determine the precise time of ovulation in order to find the relatively fertile and the relatively infertile days in the cycle. The signifier sperm can refer to: (mass noun, from Greek sperma = seed) a substance which consists of spermatozoa and which is a component of semen (mass noun) semen itself (informally, count noun with plural sperm or sperms) a single spermatozoon (= sperm cell) sperma ceti (Latin ceti, genitive of cetus = whale... The missionary position is the most commonly used position for sexual intercourse in humans The cowgirl sex position is a position frequently combined with kissing, caressing, and embracing of the paramour. ... Fertility Awareness (FA) is the practice of observing one or more of a woman’s primary fertility signs to determine the fertile and infertile phases of her cycle. ... Birth control is a regimen of one or more actions, devices, or medications followed in order to deliberately prevent or reduce the likelihood of a woman giving birth or becoming pregnant. ...


People who have heard about the menstrual cycle and ovulation may commonly and mistakenly assume, for contraceptive purposes, that menstrual cycles always take a regular 28 days, and that ovulation always occurs 14 days after beginning of the menses. This assumption may lead to unintended pregnancies. Note too that not every bleeding event counts as a menstruation, and this can mislead people in their calculation of the fertile window.


If a woman wants to conceive, the most fertile time occurs between 19 and 10 days prior to the expected menses. Many women use ovulation detection kits that detect the presence of the LH surge in the urine to indicate the most fertile time. Other ovulation detection systems rely on observation of one or more of the three primary fertility signs (basal body temperature, cervical fluid, and cervical position).


Among women living closely together, the onsets of menstruation may tend to synchronise somewhat. Researchers first described this phenomenon in 1971, and explained it by the action of pheromones in 1998 (Stern and McClintock 1998). However, subsequent research has called this conclusion into question. It has been suggested that Bombykol be merged into this article or section. ... The McClintock effect (also known as Menstrual Synchrony) is the observed phenomenon that the menstrual cycles of women who live together (such as in prisons, convents, bordellos, dormitories, etc. ...


Hormonal control

Extreme intricacies regulate the menstrual cycle. For many years, researchers have argued over which regulatory system has ultimate control: the hypothalamus, the pituitary, or the ovary with its growing follicle; but all three systems have to interact. In any scenario, the growing follicle has a critical role: it matures the lining, provides the appropriate feedback to the hypothalamus and pituitary, and modifies the mucus changes at the cervix. Two sex hormones play a role in the control of the menstrual cycle: estradiol and progesterone. While estrogen peaks twice, during follicular growth and during the luteal phase, progesterone remains virtually absent prior to ovulation, but becomes critical in the luteal phase and during pregnancy. Many tests for ovulation check for the presence of progesterone. These sex hormones come under the influence of the pituitary gland, and both FSH and LH play necessary roles. FSH stimulates immature follicles in the ovaries to grow. LH triggers ovulation. The gonadotropin-releasing hormone of the hypothalamus controls the pituitary, yet both the pituitary and the hypothalamus receive feedback from the follicle. After ovulation the corpus luteum — which develops from the burst follicle and remains in the ovary — secretes both estradiol and progesterone. Only if pregnancy occurs do hormones appear in order to suspend the menstrual cycle, while production of estradiol and progesterone continues. Abnormal hormonal regulation leads to disturbance in the menstrual cycle. Sex hormones are hormones that affect the reproductive system. ... Estradiol (17-beta estradiol) is a sex hormone. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ... In botany, a follicle is a type of simple dry fruit produced by certain flowering plants. ... Gonadotropin-releasing hormone 1 (GNRH1 also called LHRH) is a peptide hormone responsible for the release of FSH and LH from the anterior pituitary. ...


Some women with neurological conditions experience increased activity of their conditions at about the same time every month. 80 percent of women with epilepsy have more seizures than usual in the phase of their cycle when progresterone declines and estrogen increases. Neurology is a branch of medicine dealing with the nervous system and its disorders. ...


Mice have been used as an experimental system to investigate possible mechanisms by which levels of sex steroid hormones might regulate nervous system function. During the part of the mouse estrous cycle when progesterone is highest, the level of nerve-cell GABA receptor subtype delta was high. Since these GABA receptors are inhibitory, nerve cells with more delta receptors are less likely to fire than cells with lower numbers of delta receptors. During the part of the mouse estrous cycle when estrogen levels are higher than progesterone levels, the number of delta receptors decrease, increasing nerve cell activity, in turn increasing anxiety and seizure susceptibility. (Maguire et al., 2005) Drawing by Santiago Ramón y Cajal of cells in the pigeon cerebellum. ... The GABA-a pentameric receptor The GABAA receptor is one of the three ligand-gated ion channels responsible for mediating the effects of Gamma-AminoButyric Acid (GABA), the major inhibitory neurotransmitter in the human body. ... Inhibitory Postsynaptic Potential is commonly abbreviated to Impulses are transmitted from neuron to neuron by the release of a chemical transmitter across synaptic clefts from the synaptic vesicles along the axon to the postsynaptic receptors of another neuron. ...


Hidden ovulation

Main article: concealed ovulation

Unlike almost all other species, the external physical changes of a human female near ovulation are very subtle. A woman may sense her own ovulation while it may remain indiscernible to others; this is considered to have sociobiological significance. In contrast, other species often signal receptivity through heat. The great apes are the only other mammals to have hidden ovulation. Human and bonobo females have concealed ovulation or hidden estrus. ... Sociobiology is a synthesis of scientific disciplines that attempts to explain behaviour in all species by considering the evolutionary advantages of social behaviours. ...


The ovary as an egg-bank

Evidence suggests that eggs are formed from germ cells early in fetal life. The number is reduced to an estimated 400,000 to 450,000 immature eggs residing in each ovary at puberty. The menstrual cycle, as a biologic event, allows for ovulation of one egg typically each month. Thus over her lifetime a woman will ovulate approximately 400 to 450 times. All the other eggs dissolve by a process called atresia. As a woman's total egg supply is formed in fetal life, to be ovulated decades later, it has been suggested that this long lifetime may make the chromatin of eggs more vulnerable to division problems, breakage, and mutation than the chromatin of sperm, which are produced continuously during a man's reproductive life. This possibility is supported by the observation that fetuses and infants of older mothers have higher rates of chromosome abnormalities than those of older fathers. Atresia is a condition in which a body orifice or passage in the body is abnormally closed or absent. ...


The anovulatory menstrual cycle

Not all menstruations result from an ovulatory menstrual cycle (Anovulatory cycle - literally 'an-' absence of 'ovulation'). In some women, follicular development may start but not complete, nevertheless estrogens will form and will stimulate the uterine lining. Sooner or later the uterus will shed this lining. As no ovulation and no progesterone involvement occurs, doctors call this type of bleeding an estrogen breakthrough bleeding, and cannot always predict its duration or frequency. Anovulatory bleeding commonly occurs prior to menopause (premenopause) or in women with polycystic ovary syndrome. Infrequent or irregular ovulation is called oligoovulation. The anovulatory cycle is a menstrual cycle characterized by varying degrees of menstrual intervals and the absence of ovulation and a luteal phase. ... Menopause (also known as the Change of life or climacteric) is a stage of the human female reproductive cycle that occurs as the ovaries stop producing estrogen, causing the reproductive system to gradually shut down. ... Polycystic Ovary by Sonography Polycystic ovary syndrome (PCOS, also known clinically as Stein-Leventhal syndrome), is an endocrine disorder that affects 5–10% of women. ...


Cycle abnormalities

Main article: Menstrual disorder

A menstrual disorder is an irregular condition in a womans menstrual cycle. ...

Frequency

The "normal menstrual cycle" occurs every 28 days ± 7 days.


The medical term for cycles with intervals of 21 days or fewer is polymenorrhea and, on the other hand, the term for cycles with intervals exceeding 35 days is oligomenorrhea (or amenorrhea if intervals exceed 180 days). Polymenorrhea ... Oligomenorrhea is the medical term for infrequent or light menstrual periods in women of child-bearing age. ... Amenorrhoea (BE) or amenorrhea (AmE) is the absence of a menstrual period in a woman of reproductive age. ...


Flow

The normal menstrual flow amounts to 50 ml ± 30 ml. It follows a "crescendo-decrescendo" pattern; that is, it starts at a moderate level, increases somewhat, and then slowly tapers. Sudden heavy flows or amounts in excess of 80 ml (hypermenorrhea or menorrhagia) may stem from hormonal disturbance, uterine abnormalities, including uterine leiomyoma or cancer, and other causes. Doctors call the opposite phenomenon, of bleeding very little, hypomenorrhea. Menorrhagia is an abnormally heavy and prolonged menstrual period. ... A leiomyoma (plural is leiomyomata) is a benign smooth muscle neoplasm that is not premalignant. ... When normal cells are damaged beyond repair, they are eliminated by apoptosis. ...


Duration

The typical woman bleeds ("is on her period") for three to seven days out of each month.


Prolonged bleeding (metrorrhagia, also meno-metrorrhagia) no longer shows a clear interval pattern. Dysfunctional uterine bleeding refers to hormonally caused bleeding abnormalities, typically anovulation. All these bleeding abnormalities need medical attention; they may indicate hormone imbalances, uterine fibroids, or other problems. As pregnant patients may bleed, a pregnancy test forms part of the evaluation of abnormal bleeding. Dysfunctional Uterine Bleeding (DUB) is the most common cause of functional abnormal uterine bleeding, which is abnormal genital tract bleeding based in the uterus and found in the absence of demonstrable organic pathology. ... A pregnancy test is a test to determine whether or not a woman is pregnant. ...


The birth control pill

Main article: Birth control pill

Estrogens and progesterone-like hormones make up the main active ingredients of birth control pills. Typically they tend to mimic a menstrual cycle in appearance, but to suppress the critical event of the ovulatory cycle, namely ovulation. Normally, a woman takes hormone pills for 21 days, followed by 7 days of non-functional placebo sugar pills or no pills at all; then the cycle starts again. During the 7 placebo days, a withdrawal bleeding occurs; this differs from ordinary menstruation, and skipping the placebos and continuing with the next batch of hormone pills may suppress it. (Two main versions of the pill exist: monophasic and triphasic. With triphasic pills, skipping of the placebos and continuing with the next month's dose can make a woman more likely to experience spotting or breakthrough bleeding.) In 2003 the United States Food and Drug Administration (FDA) approved low-dose monophasic birth control pills which induce withdrawal bleedings only every 3 months. Oral contraceptives are contraceptives which are taken orally and inhibit the bodys fertility by chemical means. ... Oral contraceptives are contraceptives which are taken orally and inhibit the bodys fertility by chemical means. ... A placebo, from the Latin for I will please, is a medical treatment (operation, therapy, chemical solution, pill, etc. ... The Food and Drug Administration (FDA) of the United States is the government agency responsible for regulating food (human and animal), dietary supplements, drugs (human and animal), cosmetics, medical devices (human and animal), biologics, and blood products in the United States. ...


Etymology and the lunar month

The terms "menstruation" and "menses" come from the Latin mensis (month), which in turn relates to the Greek mene (moon) and to the roots of the English words month and moon — reflecting the fact that the moon also takes close to 28 days to revolve around the Earth (actually 27.32 days). The synodical lunar month, the period between two new moons (or full moons), is 29.53 days long. Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... In lunar calendars, a lunar month is the time between two successive similar syzygies (new moons or full moons). ...


Many women, when not being exposed to artificial nighttime lighting, find that their menstrual cycles occur in rhythm with the lunar cycle.


Menstrual products

While some women allow their menses to flow freely or learn to recognise when their menses will flow, most women prefer to use some artificial means to absorb or catch their menses to prevent soiling their clothes. There are a number of different methods used:

  • Sanitary towels, sanitary napkins, or pads - Somewhat rectangular pieces of material worn in the underpants to absorb menstrual flow, often with "wings," pieces that fold around the panties, and/or an adhesive backing to hold the pad in place. Reusable cloth pads are made of cotton (often organic), terrycloth, or flannel, and may be handsewn (from material or reused old clothes and towels) or storebought. Disposable synthetic pads are made of wood pulp or synthetic products, usually with a plastic lining and bleached.
  • Tampons - Disposable wads of treated rayon/cotton blends or all-cotton fleece, usually bleached, that are inserted into the vagina to absorb menstrual flow.
  • Menstrual cups - A firm, flexible cup- or bell-shaped device worn inside the vagina to catch menstrual flow. Reusable versions include rubber or silcone cups (like the Keeper, Divacup, Lunette and Mooncup). Disposable versions come in soft plastic cups (like Instead).
  • Sea sponges - Reuseable soft sponges from plant-like animals that grow on the ocean floor, worn internally to absorb blood.
  • Padettes - Disposable wads of treated rayon/cotton blend fleece that are placed within the inner labia to absorb menstrual flow.
  • Padded panties - Reuseable cloth (usually cotton) underwear with extra absorbent layers sewn in to absorb flow.
  • Blanket, towel - Large reuseable piece of cloth, most often used at night, placed between legs to absorb menstrual flow.

Pharmaceutical companies also provide products — commonly Non-steroidal anti-inflammatory drugs (NSAIDs) — to relieve menstrual cramps. A sanitary towel (U.K.) or sanitary napkin (U.S.) is an absorbent piece of material worn by a woman while she is menstruating, to absorb the flow of blood from the vagina. ... A sanitary towel (U.K.) or sanitary napkin (U.S.) is an absorbent piece of material worn by a woman while she is menstruating, to absorb the flow of blood from the vagina. ... Lingerie is a term, derived from the French language, for womens undergarments. ... Cotton plant as imagined and drawn by John Mandeville in the 14th century Cotton is a soft fiber that grows around the seeds of the cotton plant (Gossypium spp. ... Organic farming is a form of agriculture that relies on ecosystem management and attempts to reduce or eliminate external agricultural inputs, especially synthetic ones. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Flannel is a light-to-medium weight woven cloth that is commonly used to make clothing and bedsheets. ... Wood pulp is the most common material used to make paper. ... Generally, synthetic means pertaining to synthesis, i. ... Plastic is a term that covers a range of synthetic or semisynthetic polymerization products. ... A tampon is a plug of cotton or other absorbent material inserted into a body cavity or wound to absorb fluid. ... See Raion for a subnational entity. ... Cotton plant as imagined and drawn by John Mandeville in the 14th century Cotton is a soft fiber that grows around the seeds of the cotton plant (Gossypium spp. ... Cotton plant as imagined and drawn by John Mandeville in the 14th century Cotton is a soft fiber that grows around the seeds of the cotton plant (Gossypium spp. ... A menstrual cup is a type of cup or barrier worn by a woman inside her vagina during menstruation to collect menstrual fluid. ... Keeper may mean: A curator as, for example, at the British Museum A menstrual cup In some sports, a player who protects a goal A warder or guardian A gamekeeper A term used to refer to the status of a person that one is dating being worth marrying. ... A menstrual cup is a type of cup or barrier worn by a woman inside her vagina during menstruation to capture the blood. ... This article is about the animal. ... See Raion for a subnational entity. ... Cotton plant as imagined and drawn by John Mandeville in the 14th century Cotton is a soft fiber that grows around the seeds of the cotton plant (Gossypium spp. ... Lingerie is a term, derived from the French language, for womens undergarments. ... Cotton plant as imagined and drawn by John Mandeville in the 14th century Cotton is a soft fiber that grows around the seeds of the cotton plant (Gossypium spp. ... A man modeling a pair of boxer shorts A pair of mens briefs Undergarments, also called underwear, lingerie (undergarments for women), or sometimes intimate clothing, are clothes worn next to the skin, usually under other clothes. ... This article needs to be cleaned up to conform to a higher standard of quality. ... A towel is a piece of absorbent fabric or paper used for drying or wiping. ... Non-steroidal anti-inflammatory drugs, usually abbreviated to NSAIDs, are drugs with analgesic, antipyretic and anti-inflammatory effects - they reduce pain, fever and inflammation. ...


Debate

Much debate centers around which menstrual products to use. The main debate can be summarized as one between the convenience, availability, and general knowledge of disposables; versus the environmental, monetary, and potential health benefits of reuseables. A secondary aspect of this is commercial responsibility. Disposable menstrual products compose a large and powerful industry in the West, with a near monopoly on advertising, supermarket shelves, and menstrual education. This leads many people to believe that these corporate products are their only options. Many people object to the negative portrayal of menstruation in advertising; menstruation is portrayed as shameful, unnatural, smelly, and hindering. In contrast, the reuseable menstrual products industry is composed mostly of small, independent, and woman-owned, woman-positive businesses. Finally, some believe that the disposable menstrual products industry is imperialist, forcing or coercing women of other cultures to leave their reuseable, inexpensive or free menstrual products to become consumers of disposables.


A summary of the main issues of debate:

Environmental waste 
Tampons, pads, disposable cups and their packaging generate tons of bulky waste per year, much of which is not biodegradable.
Cost 
Many disposables have a cheaper upfront cost than reuseables, but over time (a period of a few months), this cost is recouped many times over from savings on reuseables. Many reuseables can also be made for free from old clothes or other scraps of cloth.
Health concerns 
1. Bleaching - Many women object to the chlorine bleaching of disposable menstrual products, which leaves trace amounts of dioxin, a carcinogen, in their bodies. 2. Scents and deodorizers - Chemical scents and deodorizers can cause rashes, irritation, and allergic reactions. They can upset the pH balance of the vagina and cause yeast infections.
Health concerns specific to tampons 
Toxic Shock Syndrome is indirectly caused by Staphylococcus aureus, which can thrive in the environment found in tampon fibers. TSS is very rare, with only approx. 40 cases per year in the UK. Tampon-associated TSS is not caused by the staphylococci invading into tissues, but rather as a result of the release of a protein called toxic shock syndrome toxin (TSST)[6]. TSST is absorbed into the body where it acts as a toxin. Toxic Shock Syndrome can, and does, cause death. TSS can be avoided by using the least absorbent tampon possible for one's flow, and changing tampons at least every 8 hours, or by avoiding tampons altogether. This may apply to sea sponges also, though no cases of TSS with sea sponge use have been reported.

In chemistry, to bleach something generally means to whiten it or oxidize it. ... Structure of Tetrachlorobenzodioxin Dioxin is the popular name for the family of chlorinated organic compounds comprising of Polychlorinated Dibenzo Furans (PCDF) and Polychlorinated Dibenzo Dioxins (PCDD). ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... A tampon with an applicator. ... Toxic shock syndrome (TSS) is a rare but potentially fatal disease caused by a bacterial toxin. ... Binomial name Staphylococcus aureus Rosenbach, 1884 Staphylococcus aureus (which is occasionally given the nickname golden staph) is a bacterium, frequently living on the skin or in the nose of a healthy person, that can cause illnesses ranging from minor skin infections (such as pimples, boils, and cellulitis) and abscesses, to... This article is about the animal. ...

Culture and menstruation

Mysticism

Mystics have sometimes elaborated "equivalencies", analogising the waxing and waning of the moon with influences on human menstruation. In this spiritual, moon goddess, or astrological context some women call menstruation their "moontime". Some ancient views also regarded menstruation as a cleansing of the body: compare bloodletting as a major medical treatment of pre-modern times. Mysticism from the Greek (muo, concealed) is the pursuit of achieving communion or identity with, or conscious awareness of, ultimate reality, the divine, spiritual truth, or God through direct experience, intuition, or insight; and the belief that such experience is an important source of knowledge or understanding. ... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... In the study of mythology, a lunar deity is a god or goddess associated with or symbolizing the Moon: see Moon (mythology). ... Astrology refers to any of several systems, traditions or beliefs in which knowledge of the apparent positions of celestial bodies is held to be useful in understanding, interpreting, and organizing knowledge about human affairs and events on earth. ... Bloodletting (or blood-letting, in modern medicine referred to as phlebotomy) was a popular medical practice from antiquity up to the late 19th century, involving the withdrawal of often considerable quantities of blood from a patient in the belief that this would cure or prevent illness and disease. ...


Religion

Many religions have menstruation-related rituals.


Christianity on menstruation

Some Christian denominations, including some (but by no means all) authorities of the Orthodox Church [7], advise women not to receive communion during their menstrual period. Other denominations follow the rules laid out in the Holiness Code section of Leviticus, somewhat similar to the Jewish ritual of Niddah. Several Christian Churches or church bodies are commonly referred to as Orthodox. Most of them are identifiable as part of Eastern Christianity. ... The Holiness Code appears at Leviticus 17-26, and is so called due to its highly repeated use of the word Holy. ...


Most Christian denominations do not follow any specific rituals or rules related to menstruation.


Islam on menstruation

The traditional Islamic interpretation of the Qur'an forbids intercourse, but not physical intimacy, during a woman's menstrual cycle. During menstrual cycle, women are not allowed to perform prayers and fasting. [8] The Quran (Arabic , literally the recitation; also called or The Noble Quran; also transliterated Quran, Koran, and less commonly Alcoran) is the holy book of Islam. ...


Judaism on menstruation

For more details on this topic, see Niddah.

A ritual exclusion applies to a woman while menstruating and for about a week thereafter, until she immerses herself in a mikvah (ritual bath). While Orthodox Jews follow this exclusion, many Jews in other branches of the religion do not. Niddah (or nidah, nidda, nida; Hebrew), in Judaism, is technically a state of marital separation when a woman is menstruating and seven subsequent days until she immerses in a ritual bath known as a mikvah. ... Mikvah (or mikveh) (Hebrew: מִקְוָה; Tiberian Miqwāh, Standard Hebrew Miqva) (plural, mikvaot) is a ritual bath used for immersion in a purification ceremony within Judaism. ...


Hindu tradition

During the menses, Hindu woman avoid routine work to maintain religious privacy. They do not go into the kitchen or pooja room. They do not touch any member of the family and dont exchange clothes with them. They use mats and wollen as bed for sleeping. The privacy is maintained for three days, with the starting day counted as one day. On fourth day morning, she takes bath and ends the ritual. On the fifth day, she takes an oil bath and is back to the regular routine. The practice is used in various forms by all Hindus but strictly followed by Brahmins.


Ayyavazhi

Almost all that practiced by women during menses in Hindu culture were practices in Ayyavazhi society. But they use to enter the kitchen and use to take bath every day unlike others. The menstrual cycle is the periodic change in a womans body that occurs every month between puberty and menopause and that relates to reproduction. ... A Hindu (archaic Hindoo), as per modern definition is an adherent of philosophies and scriptures of Hinduism, the predominant religious, philosophical and cultural system of the Indian subcontinent and the island of Bali. ... Ayyavazhi (Tamil: path of the father), officially a Tamil Hindu monistic sect that originated in South India in the mid-19th century. ...


Menstruation in other mammals

A regular menstrual cycle as described here only occurs in the great apes. Menstrual cycles vary in length from an average of 29 days in orangutans to an average of 37 days in chimpanzees. Genera Subfamily Ponginae Pongo - Orangutans Gigantopithecus (extinct) Sivapithecus (extinct) Subfamily Homininae Gorilla - Gorillas Pan - Chimpanzees Homo - Humans Paranthropus (extinct) Australopithecus (extinct) Sahelanthropus (extinct) Ardipithecus (extinct) Kenyanthropus (extinct) Pierolapithecus (extinct) (tentative) The Hominids (Hominidae) are a biological family which includes humans, extinct species of humanlike creatures and the other great apes... Type Species Simia pygmaeus Linnaeus, 1760 Species Pongo pygmaeus Pongo abelii The orangutans are two species of great apes with long arms and reddish, sometimes brown, hair native to Malaysia and Indonesia. ... Type Species Simia troglodytes Blumenbach, 1775 Species Pan troglodytes Pan paniscus Chimpanzee, often abbreviated to chimp, is the common name for two species in the genus Pan. ...


Females of other mammalian species go through certain episodes called "estrus" or "heat" in each breeding season. During these times, ovulation occurs and females become receptive to mating, a fact advertised to males in some way. If no fertilisation takes place, the uterus reabsorbs the endometrium: no menstrual bleeding occurs. Significant differences exist between the estrus and the menstrual cycle. Some animals, such as domestic cats and dogs do produce a very short and mild menstrual flow. However, due to its small amount (and personal cleanliness in cats) it passes pet owners largely unnoticed. Orders Subclass Multituberculata (extinct) Plagiaulacida Cimolodonta Subclass Palaeoryctoides (extinct) Subclass Triconodonta (extinct) Subclass Eutheria (includes extinct ancestors)/Placentalia (excludes extinct ancestors) Afrosoricida Artiodactyla Carnivora Cetacea Chiroptera Cimolesta (extinct) Creodonta (extinct) Condylarthra (extinct) Dermoptera Desmostylia (extinct) Embrithopoda (extinct) Hyracoidea Insectivora Lagomorpha Litopterna (extinct) Macroscelidea Mesonychia (extinct) Notoungulata (extinct) Perissodactyla Pholidota Plesiadapiformes... Estrus (also spelled œstrus) or heat in female mammals is the period of greatest female sexual responsiveness usually coinciding with ovulation. ... Estrus (also spelled œstrus) or heat in female mammals is the period of greatest female sexual responsiveness usually coinciding with ovulation. ... It has been suggested that Cat breed be merged into this article or section. ... Trinomial name Canis lupus familiaris (Linnaeus, 1758) This article is about the domestic dog. ...


References

Notes

  1. ^  "At what age does a girl get her first period?," from Menstruation and the Menstrual Cycle, National Women's Health Information Center (accessed June 11, 2005).
  2. ^  Ibid., "What is a typical menstrual period like?" (accessed June 11, 2005).
  3. ^  "Lower olfactory threshold during the ovulatory phase of the menstrual cycle" by E. Navarrete-Palacios, R. Hudson, G. Reyes-Guerrero and R. Guevara-Guzman in Biol Psychol. (2003) volume 63 page 269-279 PMID 12853171
  4. ^  M. Ball, "A prospective field trial of the Ovulation Method", European Journal of Obstetrical and Gynaecological Reproductive Biology, 6/2, 63-6, 1976. (Summarized at Trials of the Billings Ovulation Method accessed November 3, 2005)
  5. ^  "Medical Microbiology" 4th ed. Online textbook Samule Baron, editor. (1996) Published by University of Texas Medical Branch; Galveston (TX)

External links

Hygiene products

  • Love Your Blood: An info-zine on menstrual products and their alternatives
  • The rags: paraphernalia of menstruation
  • Eight Myths About Washable Menstrual Pads Dispelled
  • Tampaction and The Bloodsisters Project- Menstrual activism against chlorine bleaching, excessive packaging, and negative attitudes toward menstruation in the West

  Results from FactBites:
 
Howstuffworks "How To Get Pregnant Using An Ovulation Calendar" (580 words)
Ovulation is the process by which an ovary produces and releases an egg.
If the egg does not become fertilized during ovulation (that is, if you do not become pregnant), the thickened endometrial tissue breaks down and passes, along with the unfertilized egg, out of the cervix, through the vagina, and out of the body as the menstrual discharge.
Ovulation - the time during a menstrual cycle when you may become pregnant - is regulated by a complex system of hormonal and chemical secretions from the ovaries, the hypothalamus (part of the brain), and the pituitary gland (the master gland that controls most hormonal secretions).
Mensturation: Knowing When You Ovulation (1063 words)
Ovulation refers to a specific phase in your menstrual cycle.
Many women choose to chart their menstrual cycle in order to determine when they are ovulating.
Ovulation kits are now widely available to help you to determine when you are ovulating.
  More results at FactBites »

 
 

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