What Are The Phases Of A Menstrual Cycle

What Are The Phases Of A Menstrual Cycle – This article is about the biological aspects of the reproductive cycle in humans. For information specific to monthly periods, see Menstruation and Menstruation (mammal).

The menstrual cycle is a series of natural changes in hormone production and the uterine and ovarian structures of the female reproductive system that make pregnancy possible. The ovarian cycle regulates the production and release of eggs and the cyclical release of estrogen and progesterone. The uterine cycle regulates the preparation and maintenance of the lining of the uterus (womb) to receive an embryo. These cycles are usually simultaneous and coordinated with an interval of 21 and 35 days with an interval of 28 days and continue for about 30-45 years.

What Are The Phases Of A Menstrual Cycle

What Are The Phases Of A Menstrual Cycle

Naturally occurring hormones drive cycles; The periodic rise and fall of follicle-stimulating hormone stimulates the production and development of oocytes (immature egg cells). The hormone estrogen stimulates the lining of the uterus (endometrium) to thicken and accommodate the embryo when fertilization occurs. A thickened placental blood supply provides nutrients to a successfully implanted embryo. If implantation does not occur, the lining breaks down and blood is released. Triggered by a drop in progesterone levels, menstruation (“period” in common parlance) is the periodic shedding of the lining and is a sign that pregnancy has not occurred.

Your Menstrual Cycle Explained

Each cycle occurs in phases based on evts in the ovary (ovarian cycle) or uterus (uterine cycle). The ovarian cycle consists of the follicular phase, ovulation, and the luteal phase; The uterine cycle consists of menstrual, proliferative and secretory phases. The first day of the menstrual cycle is the first day of the period, which lasts about five days. On the fourth day, the egg is usually released from the ovary. Marche (beginning of first period) usually occurs around the age of twelve.

The menstrual cycle can cause some women to experience premenstrual syndrome, which includes tender breasts and fatigue. More severe symptoms that affect daily life are classified as premenstrual dysphoric disorder and are experienced by 3-8% of women. During the first few days of menstruation, some women experience period pain that spreads from the abdomen to the back and upper thighs. Hormonal birth control can alter the menstrual cycle.

The menstrual cycle includes the ovarian and uterine cycles. The ovarian cycle describes the changes that occur in the ovarian follicles,

But the uterine cycle describes changes in the lining of the uterus. Both cycles can be divided into phases. The ovarian cycle consists of alternating follicular and luteal phases and the uterine cycle consists of menstruation, proliferative phase and secretory phase.

How Many Phases Does The Menstrual Cycle Have?

The menstrual cycle is controlled by the hypothalamus in the brain and the anterior pituitary gland at the base of the brain. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which causes the nearby anterior pituitary to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Before puberty, GnRH is released in less constant amounts and at a constant rate. After puberty, GnRH is released in large pulses, and the frequency and amount of these determine how much FSH and LH are produced by the pituitary.

Measured from the first day of one period to the first day of the next, menstrual cycle length varies but has an average length of 28 days.

During puberty, a child’s body begins to mature into an adult body capable of sexual reproduction; The first period (called Marche) occurs at about 12 years of age and continues for about 30-45 years.

What Are The Phases Of A Menstrual Cycle

The ovaries regularly alternate between the luteal and follicular phases during the monthly menstrual cycle between March and Mopause.

Food Charts For Each Phase Of Your Menstrual Cycle

During the follicular phase, stimulated by gradually increasing amounts of estrogen, blood flow stops and the lining of the uterus thickens. The follicles in the ovary begin to develop under the influence of a complex interplay of hormones and after several days one or occasionally two become dominant, while the non-dominant follicles shrink and die. About 10-12 hours after mid-cycle there is a surge of luteinizing hormone called the LH surge,

The remnants of the dominant follicle in the ovary become the corpus luteum – a body whose primary function is to produce large amounts of the hormone progesterone.

Under the influence of progesterone, the lining of the uterus changes to prepare for implantation of the embryo to establish pregnancy. The thickness of the endometrium increases in response to mounting levels of estrogen, which is released from the antral follicle (mature ovarian follicle) into the circulation. Estrogen peaks on the third day of the cycle and coincides with ovulation. If implantation does not occur in about two weeks, the corpus luteum degenerates into a corpus albicans, which no longer produces hormones, causing a sharp drop in both progesterone and estrogen levels. This collapse causes the uterus to shed its lining during menstruation; Low levels of estrogen are reached during this time.

In the ovulatory menstrual cycle, the ovarian and uterine cycles are simultaneous and coordinated and last between 21 and 35 days, with a population average of 27–29 days.

The Menstrual Cycle

Although the average human menstrual cycle is the same as the Lgth lunar cycle, there is no causal relationship between the two.

Ovaries contain a limited number of egg stem cells, granulosa cells, and theca cells, which together form primordial follicles.

About 7 million immature eggs are already formed in the ovary at about 20 weeks of pregnancy. This decreases to about 2 million by the time a girl is born and by 300,000 by her first menstrual cycle. On average, one egg matures and is released during ovulation every month after March.

What Are The Phases Of A Menstrual Cycle

The development of the egg is called oogenesis and only one cell survives division to await fertilization. Other cells are rejected as polar bodies, which cannot be fertilized.

Phases Of The Menstrual Cycle — Natural Fertility Geelong

The follicular phase is the first part of the ovarian cycle and ds with the completion of the antral follicles.

Meiosis (cell division) is incomplete in egg cells until the antral follicle is formed. At this stage, an ovarian follicle is usually fully matured and ready to release an egg.

The follicular phase lasts 14 days in women aged 18-24 years compared to 10 days in women aged 40-44 years, significantly with age.

Through the influence of increased follicle stimulating hormone (FSH) during the first days of the cycle, some ovarian follicles are stimulated. Developing over the better part of a year, these follicles compete with each other for dominance in a process known as folliculogenesis. All but one of these follicles stop growing, but the dominant follicle – the one with the most FSH receptors – continues to maturity. The remaining follicles die in a process called follicular atresia.

Define Menstrual Cycle And Explain Its Various Phases With Diagram

Luteinizing hormone (LH) stimulates further growth of the ovarian follicle. The follicle that reaches maturity is called the antral follicle and contains the ovule (egg cell).

The theca cells develop receptors that bind LH and secrete large amounts of androstadione in response. At the same time the granulosa cells surrounding the maturing follicle develop receptors that bind FSH and in response begin to secrete androstadione, which is converted to estrogen by zyme aromatase. Estrogen inhibits further production of FSH and LH by the pituitary gland. This negative feedback regulates FSH and LH levels. A dominant follicle secretes estrogen and increasing estrogen levels make the pituitary more responsive to GnRH from the hypothalamus. As estrogen increases this becomes a positive feedback signal, causing the pituitary to secrete more FSH and LH. This surge of FSH and LH usually occurs one to two days before ovulation and is responsible for stimulating the rupture of the antral follicle and the release of the oocyte.

Called ovulation, it occurs when a mature egg is released from the ovarian follicles into the fallopian tube, 10-12 hours after the LH surge peaks.

What Are The Phases Of A Menstrual Cycle

Ovulation occurs in only about 10% of cycles in the first two years after March, and by the age of 40-50, the number of ovarian follicles declines.

The Menstrual Cycle: What Happens In Each Of Its Phases?

After further stimulation by LH, the corpus luteum produces and releases estrogen, progesterone, relaxin (which relaxes the uterus by inhibiting contraction of the myometrium), and inhibin (which inhibits further secretion of FSH).

The release of LH matures the egg and weakens the follicle wall in the ovary, allowing the fully developed follicle to release its egg.

If it is fertilized by sperm, the oocyte quickly matures into an oocyte, which blocks other sperm cells and becomes a mature egg. If it is not fertilized by sperm, the ovum degenerates. A mature egg is about 0.1 mm (0.0039 in) in diameter,

After being released from the ovary, the egg is carried by the fimbria into the fallopian tube – a margin of tissue at D of each fallopian tube. After about a day, the unfertilized egg disintegrates or dissolves in the fallopian tube, and the fertilized egg reaches the uterus in three to five days.

Stages Of The Menstrual Cycle

Fertilization takes place normally

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