Menstrual cycle. Menses

In all world cultures, the function of reproduction, procreation, is considered one of the main ones. The male and female reproductive system has a different structure, but performs one task: to form germ cells - gametes, upon merging of which at the time of fertilization, the development of the future human body will become possible. This article is devoted to the study of the structure and function of the female reproductive system.

General characteristics of the female reproductive organs

The female reproductive system includes external and internal genital organs, which are also called reproductive (reproducing).

The external ones, called the vulva, are visually expressed to a sufficient extent - these are the pubis, the labia majora and minor, the clitoris and the entrance to the vagina (vagina), closed by the elastic hymen, called the virgin. Let us study the external organs of the female reproductive system in more detail.

The structure of the pubis

The lower abdomen at the level of the pubic (pubic bone) forms the pubis. The bone itself, in an anatomically correct position, hangs over the entrance to the vagina and looks like an arch. Externally, the pubis has a roller-like shape, forming an elevation. A layer of fat forms under his skin. Outside, hair is formed on it. It has a clearly defined horizontal border. If a woman's body produces an excess amount of androgens - male sex hormones, the hairline increases and rises up at an acute angle to the navel. The pathology of pubic hair is a sign of sexual development.

Large and small labia

From the pubis to the anus there are two folds of skin - the labia majora, which have an outer hairline and a layer contained in them. In their connective tissue are the ducts of the Bartholin gland. It secretes a fluid that moisturizes the female genital organs. If hygiene is violated, harmful microorganisms penetrate into the tissues of the gland and cause inflammation in the form of painful seals.

Under the large ones are the small labia, densely braided with blood vessels and nerves. In their upper part there is an organ homologous to the male penis - the clitoris. Its growth is inhibited by the hormones of the female reproductive system - estrogens. The clitoris contains a large number of nerves and blood vessels, which means it is highly sensitive. If a girl or woman has a greatly enlarged clitoris, this can be a clear sign of hormonal pathology.

entrance to the vagina

The vulva, in addition to the pubis, large and small labia, the clitoris, includes the entrance to the vagina. At a distance of up to 2 centimeters from it, there is a hymen in depth. It consists of connective tissue and has several holes through which blood flows during menstruation.

Internal reproductive organs of a woman

These include the vagina (vagina), uterus, ovaries, and fallopian tubes. All of them are located in the pelvic cavity. Their functions are the maturation and entry of fertilized female sex gamete-ovules into the uterine cavity. In it, the embryo will develop from the zygote.

The structure of the vagina

The vagina is an elastic tube made up of muscle and connective tissue. It is located from the genital slit towards the uterus and has a length of 8 to 10 cm. Located in the small pelvis, the vagina enters the cervix. It has an anterior and posterior walls, as well as a vault - the upper section of the vagina. The posterior fornix of the vagina is deeper than the anterior.

The vagina is located at an angle of 90 degrees to the surface of the uterus itself. Thus, the internal female genital organs, which include the vagina, are densely braided with arterial and venous vessels, as well as nerve fibers. The vagina is separated by a thin connective tissue wall from the bladder. It is called the vesico-vaginal septum. The lower part of the vaginal wall is posteriorly separated from the lower part of the large intestine by the perineal body.

Neck and functions

The vagina enters the canal, called the cervical, and the junction itself is the external pharynx. Its shape differs in women who have given birth and those who have not given birth: if the pharynx is punctate-oval, the uterus did not bear the fetus, and the appearance of the gap is typical for those who gave birth. The uterus itself is an unpaired hollow muscular organ, consisting of the body and neck and located in the small pelvis. Considering the structure of the female reproductive system and its functions, it becomes clear that it is responsible for the formation and development of the embryo, as well as for the process of pushing the fetus out as a result of labor. Let's return to the structure of its lower section - the neck. It is connected to the upper part of the vagina and has the shape of a cone (in nulliparous) or a cylinder. The vaginal area of ​​the cervix is ​​up to three centimeters long and is anatomically divided into anterior and posterior lips. The cervix and pharynx are transformed with the age of a woman.

Inside the cervix is ​​the cervical canal, ending in the internal os. It is lined with secretory glands that secrete mucus. If its excretion is disturbed, blockage and the formation of cysts can occur. Mucus has bactericidal properties and prevents infection of the uterine cavity. 4-6 days before the release of the egg from the ovary, the mucus becomes less concentrated, so spermatozoa can easily penetrate through it into the uterus, and from there into the fallopian tubes.

After ovulation, the cervical secret increases its concentration, and its pH decreases from neutral to acidic. The pregnant woman is closed with a clot of cervical mucus in the neck area. During the menstrual period, the cervical canal opens slightly so that the torn off layer of the endometrium can come out. This may be accompanied by aching pain in the lower abdomen. During labor, the cervical canal can open up to 10 cm in diameter. This contributes to the birth of a child.

Among the most common diseases of the cervix can be called its erosion. It appears as a result of damage to the mucous layer caused by infections or injuries (abortions, complicated childbirth). In time, unrevealed and untreated erosion can cause inflammatory processes and even cancer.

Fallopian tubes

The fallopian tubes, also called oviducts or fallopian tubes, are 2 elastic tubes located in the abdominal cavity and entering the bottom of the uterus. The free edge of the oviduct has fimbriae. Their beating ensures the advancement of the egg that has left the ovary into the lumen of the tube itself. The length of each oviduct is from 10 to 12 cm. It is divided into sections: a funnel, which has an extension and is equipped with fimbriae, an ampulla, an isthmus, a part of the canal that enters the uterine wall. For the normal development of pregnancy, a condition such as complete patency of the oviducts is necessary, otherwise the woman will experience infertility. The most common pathologies of the fallopian tubes are adhesions, salpingitis and hydrosalpinx.

All of these diseases cause tubal infertility. They are complications of chlamydia, gonorrhea, trichomoniasis, genital herpes, causing narrowing of the lumen of the fallopian tubes. Frequent abortions can provoke the appearance of adhesions that are located across the tube. Hormonal disorders cause a decrease in the mobility of the ciliary epithelium lining the oviducts, which leads to a deterioration in the motor properties of the egg.

The most dangerous complication resulting from tubal pathologies is an ectopic pregnancy. In this case, the zygote stops in the oviduct before reaching the uterus. It begins to break up and grow, stretching the pipe wall, which eventually bursts. This results in severe internal bleeding that is life threatening.

Ovaries in women

They are a paired sex gland and have a mass of 6-8 grams. The ovaries are The production of sex hormones - estrogens, controlled by the pituitary and hypothalamus - is an intrasecretory function. As glands of external secretion, they form sex cells - gametes called eggs. The biochemical composition and mechanism of action of estrogens will be studied by us later. Let us return to the structure of the female gonads - the ovaries. It should be borne in mind that the structure of the female reproductive system (as well as the male one) is directly related to the urinary system.

It is from the mesonephros (primary kidney) that the stroma of the female gonads develops. The precursors of the oocytes are oogonia, which are formed from the mesenchyme. The ovary has a protein membrane, and under it there are two layers: cortical and cerebral. The first layer contains follicles, which, maturing, form oocytes of the I and I I order, and then mature eggs. The medulla of the gland consists of connective tissue and performs a supporting and trophic function. It is in the ovaries that ovogenesis occurs - the process of reproduction, growth and maturation of female sex gametes - eggs.

The specifics of a woman

The structure of the reproductive system of the female and male individuals is controlled by special biologically active substances - hormones. They are produced by the sex glands: the testes in men and the ovaries in women. Entering the bloodstream, they target both the development of the reproductive organs and the formation of secondary sexual characteristics: body hair, development of the mammary glands, voice pitch and timbre. The development of the female reproductive system occurs under the influence of estradiol and its derivatives: estriol and estrone. They are produced by special cells of the ovary - follicles. Female hormones - estrogens lead to an increase in the volume and size of the uterus, as well as to muscle contractions of the fallopian tubes and the uterus itself, that is, the reproductive organ is being prepared for the adoption of the zygote.

The corpus luteum of the uterus produces progesterone - a hormone that stimulates the development of a child's place - the placenta, as well as an increase in the glandular epithelium of the mammary glands during pregnancy. Violation of the hormonal background of the female body leads to diseases such as uterine fibroids, endometriosis, polycystic.

Anatomical features of the female uterus

The reproductive system of the female body is composed of a unique organ in structure and function. It is located in the pelvic cavity between the bladder and rectum and has a cavity. This organ is called the uterus. To understand the mechanism of fertilization, remember that the genital organs - the ovaries in women - are connected with the fallopian tubes. The egg, entering the oviduct, then penetrates the uterus, which serves as the organ responsible for the development of the embryo (embryogenesis). It consists of three parts: the neck, which was studied earlier, as well as the body and bottom. The body of the uterus looks like an inverted pear, the expanded part of which includes two fallopian tubes.

The reproductive organ is covered with a connective tissue membrane and has two layers: muscular (myometrium) and mucous (endometrium). The latter is built from cells of squamous and cylindrical epithelium. The endometrium changes the thickness of its layer: during ovulation, it thickens, and if fertilization does not occur, this layer is torn off along with a portion of blood from the walls of the uterus - menstruation occurs. During pregnancy, the volume and increase greatly (about 8-10 times). In the cavity of the small pelvis, the uterus is suspended on three ligaments and braided with a dense network of nerves and blood vessels. Its main function is the development and nutrition of the embryo and fetus until the moment of physiological birth.

Pathology of the uterus

The structure of the female reproductive system may not always be ideal and properly functioning. One of the pathologies of the reproductive system associated with the structure of the genital organ can be a bicornuate uterus. It has two bodies, each connected to one oviduct. If the pathology of the female reproductive system concerns the structure of the endometrium, they speak of hypoplasia and aplasia of the uterus. The consequence of all the above pathologies is the termination of pregnancy or infertility.

In this article, the anatomical and physiological features of the female reproductive system were studied.

These include the labia majora, labia minora, and clitoris, which together make up the vulva. It is bordered by two folds of skin - the labia majora. They consist of adipose tissue, saturated with blood vessels, and are located in the anterior-posterior direction. The skin of the labia majora is covered with hair on the outside, and thin shiny skin on the inside, on which numerous gland ducts exit. The labia majora join in front and behind to form anterior and posterior commissures (commissures). Inward from them are the small labia, which are parallel to the large and form the vestibule of the vagina. Outside, they are covered with thin skin, and inside they are lined with a mucous membrane. They have a pink-red color, connect behind in front of the commissure of the large lips, and in front - at the level of the clitoris. They are quite richly supplied with sensitive nerve endings and are involved in achieving a voluptuous feeling.

On the eve of the vagina, the ducts of the Bartholin glands located in the thickness of the labia majora open. The secret of the Bartholin glands is intensively secreted at the time of sexual arousal and provides lubrication of the vagina to facilitate friction (periodic translational movements of the penis into the vagina) during intercourse.

In the thickness of the labia majora are the bulbs of the cavernous bodies of the clitoris, which increase during sexual arousal. At the same time, the clitoris itself also increases, which is a peculiar, greatly reduced likeness of the penis. It is located in front and above the entrance to the vagina, at the junction of the labia minora. There are a lot of nerve endings in the clitoris and during sex it is the dominant, and sometimes the only organ, thanks to which a woman experiences an orgasm.

Just below the clitoris is the opening of the urethra, and even lower is the entrance to the vagina. In women who have not lived sexually, it is covered by the hymen, which is a thin fold of mucous membrane. The hymen can have a variety of shapes: in the form of a ring, a crescent, a fringe, etc. As a rule, it breaks during the first sexual intercourse, which may be accompanied by moderate soreness and slight bleeding. In some women, the hymen is very dense and blocks the penis from entering the vagina. In such cases, sexual intercourse becomes impossible and you have to resort to the help of a gynecologist who dissects it. In other cases, the hymen is so elastic and pliable that it does not break during the first intercourse.

Sometimes with rough intercourse, especially in combination with a large penis, the rupture of the hymen can be accompanied by quite severe bleeding, such that the help of a gynecologist is sometimes necessary.

It is extremely rare for a hymen to have no opening at all. During puberty, when a girl begins her period, menstrual blood accumulates in the vagina. Gradually, the vagina overflows with blood and squeezes the urethra, making it impossible to urinate. In these cases, the help of a gynecologist is also needed.

The area located between the posterior commissure of the labia majora and the anus is called the perineum. The perineum consists of muscles, fascia, blood vessels, and nerves. During childbirth, the perineum plays a very important role: due to its extensibility, on the one hand, and elasticity, on the other, it allows the head of the fetus to pass through, providing an increase in the diameter of the vagina. However, with a very large fetus or with a rapid delivery, the perineum cannot withstand excessive stretching and may rupture. Experienced midwives know how to prevent this situation. If all the techniques for protecting the perineum are ineffective, then they resort to a perineal incision (episiotomy or perineotomy), since an incised wound heals better and faster than a lacerated one.

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Internal female reproductive organs

These include the vagina, uterus, ovaries, fallopian tubes. All these organs are located in the small pelvis - a bone "shell" formed by the inner surfaces of the ilium, ischial, pubic bones and sacrum. This is necessary to protect both the woman's reproductive system and the fetus developing in the uterus.

The uterus is a muscular organ, consisting of smooth muscles, resembling a pear in shape. The size of the uterus is on average 7-8 cm long and about 5 cm wide. Despite its small size, during pregnancy, the uterus can increase 7 times. Inside the uterus is hollow. The thickness of the walls, as a rule, is about 3 cm. The body of the uterus - its widest part, is turned upward, and the narrower one - the neck - is directed downward and slightly forward (normal), falling into the vagina and dividing its posterior wall into the posterior and anterior vaults. In front of the uterus is the bladder, and behind is the rectum.

The cervix has an opening (cervical canal) that connects the vaginal cavity with the uterine cavity.

The fallopian tubes extending from the lateral surfaces of the bottom of the uterus on both sides are a paired organ 10-12 cm long. Departments of the fallopian tube: the uterine part, isthmus and ampulla of the fallopian tube. The end of the pipe is called a funnel, from the edges of which numerous processes of various shapes and lengths (fringes) extend. Outside, the tube is covered with a connective tissue membrane, under it is a muscular membrane; the inner layer is the mucous membrane, lined with ciliated epithelium.

The ovaries are a paired organ, the gonad. Oval body: length up to 2.5 cm, width 1.5 cm, thickness about 1 cm. One of its poles is connected to the uterus by its own ligament, the second is facing the side wall of the pelvis. The free edge is open into the abdominal cavity, the opposite edge is attached to the broad ligament of the uterus. It has medulla and cortical layers. In the brain - vessels and nerves are concentrated, in the cortex - follicles mature.

The vagina is an extensible muscular-fibrous tube about 10 cm long. The upper edge of the vagina covers the cervix, and the lower one opens on the eve of the vagina. The cervix protrudes into the vagina, a domed space is formed around the cervix - the anterior and posterior vaults. The wall of the vagina consists of three layers: the outer one is dense connective tissue, the middle one is thin muscle fibers, and the inner one is the mucous membrane. Some of the epithelial cells synthesize and store glycogen stores. Normally, the vagina is dominated by Doderlein sticks, which process the glycogen of dying cells, forming lactic acid. This leads to the maintenance of an acidic environment in the vagina (pH = 4), which has a detrimental effect on other (non-acidophilic) bacteria. Additional protection against infection is carried out by numerous neutrophils and leukocytes residing in the vaginal epithelium.

The mammary glands are composed of glandular tissue: each of them contains approximately 20 separate tubuloalveolar glands, each of which has its own outlet on the nipple. In front of the nipple, each duct has an extension (ampulla or sinus) that is surrounded by smooth muscle fibers. There are contractile cells in the walls of the ducts, which reflexively contract in response to sucking, expelling the milk contained in the ducts. The skin around the nipple is called the areola, it contains many mammary-type glands, as well as sebaceous glands, which produce an oily fluid that lubricates and protects the nipple during sucking.

human reproduction

Human reproduction (human reproduction), a physiological function necessary for the preservation of man as a biological species. The process of reproduction in humans begins with conception (fertilization), i.e. from the moment of penetration of the male reproductive cell (sperm) into the female reproductive cell (egg, or ovum). The fusion of the nuclei of these two cells is the beginning of the formation of a new individual. The human fetus develops in a woman's uterus during pregnancy, which lasts 265–270 days. At the end of this period, the uterus begins to spontaneously rhythmically contract, the contractions become stronger and more frequent; the amniotic sac (fetal bladder) ruptures and, finally, a mature fetus is "expelled" through the vagina - a child is born. Soon the placenta (afterbirth) departs. The whole process, starting with contractions of the uterus and ending with the expulsion of the fetus and placenta, is called childbirth.

In more than 98% of cases, at conception, only one egg is fertilized, which leads to the development of one fetus. In 1.5% of cases, twins (twins) develop. About one in 7,500 pregnancies results in triplets.

Only biologically mature individuals have the ability to reproduce. During puberty (puberty), a physiological restructuring of the body occurs, manifested in physical and chemical changes that mark the onset of biological maturity. In a girl during this period, fat deposits around the pelvis and hips increase, the mammary glands grow and round, hair growth of the external genitalia and armpits develops. Shortly after the appearance of these, the so-called. secondary, sexual characteristics, the menstrual cycle is established.

In boys, in the process of puberty, the physique changes noticeably; the amount of fat on the abdomen and hips decreases, the shoulders become wider, the timbre of the voice decreases, hair appears on the body and face. Spermatogenesis (the formation of sperm) in boys begins somewhat later than menstruation in girls.

Reproductive system of women

reproductive organs. The female internal reproductive organs include the ovaries, fallopian tubes, uterus, and vagina.

The ovaries - two glandular organs weighing 2-3.5 g each - are located behind the uterus on both sides of it. In a newborn girl, each ovary contains an estimated 700,000 immature eggs. All of them are enclosed in small round transparent bags - follicles. The latter alternately ripen, increasing in size. The mature follicle, also called the graafian vesicle, ruptures to release the egg. This process is called ovulation. The egg then enters the fallopian tube. Usually, during the entire reproductive period of life, approximately 400 fertile eggs are released from the ovaries. Ovulation occurs monthly (around the middle of the menstrual cycle). The bursting follicle plunges into the thickness of the ovary, overgrows with scar connective tissue and turns into a temporary endocrine gland - the so-called. corpus luteum that produces the hormone progesterone.

The fallopian tubes, like the ovaries, are paired formations. Each of them stretches from the ovary and connects to the uterus (from two different sides). The length of the pipes is approximately 8 cm; they are slightly bent. The lumen of the tubes passes into the uterine cavity. The walls of the tubes contain inner and outer layers of smooth muscle fibers, which are constantly contracting rhythmically, which provides undulating movements of the tubes. From the inside, the walls of the tubes are lined with a thin membrane containing ciliated (ciliated) cells. As soon as the egg enters the tube, these cells, along with muscle contractions of the walls, ensure its movement into the uterine cavity.

The uterus is a hollow muscular organ located in the pelvic region of the abdominal cavity. Its dimensions are approximately 8 cm. Pipes enter it from above, and from below its cavity communicates with the vagina. The main part of the uterus is called the body. The non-pregnant uterus has only a slit-like cavity. The lower part of the uterus, the cervix, about 2.5 cm long, protrudes into the vagina, where its cavity, called the cervical canal, opens. When a fertilized egg enters the uterus, it sinks into its wall, where it develops throughout pregnancy.

The vagina is a hollow cylindrical formation 7–9 cm long. It is connected to the cervix along its circumference and goes to the external genitalia. Its main functions are the outflow of menstrual blood to the outside, the reception of the male genital organ and male seed during copulation and providing a passage for the fetus to be born. In virgins, the external entrance to the vagina is partially closed by a crescent-shaped fold of tissue, the hymen. This fold usually leaves enough room for menstrual blood to drain; after the first copulation, the opening of the vagina expands.

Milk glands. Full (mature) milk in women usually appears approximately 4–5 days after birth. When a baby suckles, there is an additional powerful reflex stimulus for the glands to produce milk (lactation).

The menstrual cycle is established shortly after the onset of puberty under the influence of hormones produced by the endocrine glands. In the early stages of puberty, pituitary hormones initiate ovarian activity, triggering a complex of processes that take place in the female body from puberty to menopause, i.e. for approximately 35 years. The pituitary gland cyclically secretes three hormones that are involved in the process of reproduction. The first - follicle-stimulating hormone - determines the development and maturation of the follicle; the second - luteinizing hormone - stimulates the synthesis of sex hormones in the follicles and initiates ovulation; the third - prolactin - prepares the mammary glands for lactation.

Under the influence of the first two hormones, the follicle grows, its cells divide, and a large fluid-filled cavity is formed in it, in which the oocyte is located. The growth and activity of follicular cells are accompanied by their secretion of estrogens, or female sex hormones. These hormones can be found both in the follicular fluid and in the blood. The term estrogen comes from the Greek oistros (fury) and is used to refer to a group of compounds that can cause oestrus (oestrus) in animals. Estrogens are present not only in the human body, but also in other mammals.

Luteinizing hormone stimulates the rupture of the follicle and the release of the egg. After that, the cells of the follicle undergo significant changes, and a new structure develops from them - the corpus luteum. Under the action of luteinizing hormone, it, in turn, produces the hormone progesterone. Progesterone inhibits the secretory activity of the pituitary gland and changes the state of the mucous membrane (endometrium) of the uterus, preparing it to receive a fertilized egg, which must be introduced (implanted) into the uterine wall for subsequent development. As a result, the wall of the uterus thickens significantly, its mucosa, containing a lot of glycogen and rich in blood vessels, creates favorable conditions for the development of the embryo. The coordinated action of estrogens and progesterone ensures the formation of the environment necessary for the survival of the embryo and the preservation of pregnancy.

The pituitary gland stimulates the activity of the ovaries approximately every four weeks (ovulatory cycle). If fertilization does not occur, most of the mucous along with the blood is rejected and enters the vagina through the cervix. Such cyclical bleeding is called menstruation. For most women, bleeding occurs approximately every 27 to 30 days and lasts 3 to 5 days. The entire cycle ending with the shedding of the lining of the uterus is called the menstrual cycle. It is regularly repeated throughout the reproductive period of a woman's life. The first periods after puberty may be irregular, and in many cases they are not preceded by ovulation. Menstrual cycles without ovulation, often found in young girls, are called anovulatory.

Menstruation is not at all the release of "spoiled" blood. In fact, the discharge contains very small amounts of blood mixed with mucus and uterine lining tissue. The amount of blood lost during menstruation is different for different women, but on average does not exceed 5-8 tablespoons. Sometimes minor bleeding occurs in the middle of the cycle, which is often accompanied by mild abdominal pain, characteristic of ovulation. Such pains are called mittelschmerz (German "median pains"). Pain experienced during menstruation is called dysmenorrhea. Usually dysmenorrhea occurs at the very beginning of menstruation and lasts 1-2 days.

Pregnancy. The release of the egg from the follicle in most cases occurs approximately in the middle of the menstrual cycle, i.e. 10-15 days after the first day of the previous menstruation. Within 4 days, the egg moves through the fallopian tube. Conception, i.e. fertilization of the egg by the sperm takes place in the upper part of the tube. This is where the development of a fertilized egg begins. Then it gradually descends through the tube into the uterine cavity, where it is free for 3-4 days, and then penetrates into the wall of the uterus, and the embryo and structures such as the placenta, umbilical cord, etc. develop from it.

Pregnancy is accompanied by many physical and physiological changes in the body. Menstruation stops, the size and mass of the uterus increase sharply, the mammary glands swell, in which preparations for lactation are underway. During pregnancy, the volume of circulating blood exceeds the initial one by 50%, which significantly increases the work of the heart. In general, the period of pregnancy is a heavy physical load.

Pregnancy ends with the expulsion of the fetus through the vagina. After childbirth, after about 6 weeks, the size of the uterus returns to its original size.

Menopause. The term "menopause" is derived from the Greek words meno ("monthly") and pausis ("cessation"). Thus, menopause means the cessation of menstruation. The entire period of extinction of sexual functions, including menopause, is called menopause.

Menstruation also stops after the surgical removal of both ovaries, performed in certain diseases. Exposure of the ovaries to ionizing radiation can also lead to the cessation of their activity and menopause.

Approximately 90% of women stop menstruating between the ages of 45 and 50. This can happen abruptly or gradually over many months, when periods become irregular, the intervals between them increase, the bleeding periods themselves gradually shorten and the amount of blood lost decreases. Sometimes menopause occurs in women under the age of 40. Equally rare are women with regular menstruation at 55 years of age. Any bleeding from the vagina that occurs after menopause requires immediate medical attention.

Menopausal symptoms. During the period of cessation of menstruation or immediately before it, many women develop a complex set of symptoms that together make up the so-called. menopausal syndrome. It consists of various combinations of the following symptoms: "hot flashes" (sudden redness or sensation of heat in the neck and head), headaches, dizziness, irritability, mental instability and joint pain. Most women complain only of "hot flashes", which can occur several times a day and are usually more severe at night. Approximately 15% of women do not feel anything, noting only the cessation of menstruation, and maintain excellent health.

Many women misunderstand what to expect from menopause and menopause. They are worried about the possibility of loss of sexual attractiveness or the sudden cessation of sexual activity. Some are afraid of mental disorders or general withering. These fears are based predominantly on hearsay rather than medical facts.

Reproductive system of men

The function of reproduction in men is reduced to the production of a sufficient number of spermatozoa with normal mobility and the ability to fertilize mature eggs. The male reproductive organs include the testicles (testes) with their ducts, the penis, and an accessory organ, the prostate gland.

Testicles (testicles, testicles) - paired oval glands; each of them weighs 10–14 g and is suspended in the scrotum on the spermatic cord. The testicle consists of a large number of seminiferous tubules, which, merging, form the epididymis - the epididymis. This is an oblong body adjacent to the top of each testicle. The testicles secrete male sex hormones, androgens, and produce sperm containing male germ cells - spermatozoa.

Spermatozoa are small, very mobile cells, consisting of a head carrying a nucleus, a neck, a body, and a flagellum, or tail. They develop from special cells in thin convoluted seminiferous tubules. Maturing spermatozoa (the so-called spermatocytes) move from these tubules into larger ducts that flow into spiral tubules (efferent or excretory tubules). From them, spermatocytes enter the epididymis, where their transformation into spermatozoa is completed. The epididymis contains a duct that opens into the vas deferens of the testis, and that, connecting with the seminal vesicle, forms the ejaculatory (ejaculatory) duct of the prostate gland. At the moment of orgasm, spermatozoa, together with the fluid produced by the cells of the prostate gland, vas deferens, seminal vesicle and mucous glands, are ejected from the seminal vesicle into the ejaculatory duct and further into the urethra of the penis. Normally, the volume of the ejaculate (semen) is 2.5-3 ml, and each milliliter contains more than 100 million spermatozoa.

Fertilization. Once in the vagina, the spermatozoa, with the help of tail movements, and also due to the contraction of the walls of the vagina, move into the fallopian tubes in about 6 hours. The chaotic movement of millions of spermatozoa in the tubes creates the possibility of their contact with the egg, and if one of them penetrates it, the nuclei of the two cells merge and fertilization is completed.

Infertility

Infertility, or the inability to reproduce, can be due to many reasons. Only in rare cases is it due to the absence of eggs or sperm.

female infertility. A woman's ability to conceive is directly related to age, general health, stage of the menstrual cycle, as well as psychological mood and lack of nervous tension. Physiological causes of infertility in women include the absence of ovulation, the unavailability of the uterine endometrium, infections of the genital tract, narrowing or obstruction of the fallopian tubes, and congenital anomalies of the reproductive organs. Other pathological conditions can lead to infertility if left untreated, including various chronic diseases, nutritional disorders, anemia, and endocrine disorders.

diagnostic tests. Finding out the cause of infertility requires a complete medical examination and diagnostic laboratory tests. The patency of the fallopian tubes is checked by blowing them. To assess the condition of the endometrium, a biopsy is performed (removal of a small piece of tissue) followed by microscopic examination. The function of the reproductive organs can be judged by the analysis of the level of hormones in the blood.

male infertility. If a semen sample contains more than 25% abnormal sperm, fertilization rarely occurs. Normally, 3 hours after ejaculation, about 80% of spermatozoa retain sufficient mobility, and after 24 hours, only a few of them show sluggish movements. Approximately 10% of men suffer from infertility due to insufficient sperm. Such men usually have one or more of the following defects: a small number of spermatozoa, a large number of their abnormal forms, a decrease or complete absence of spermatozoa motility, a small amount of ejaculate. The cause of infertility (sterility) may be inflammation of the testicles caused by mumps (mumps). If the testicles have not yet descended into the scrotum at the onset of puberty, the cells that produce sperm can be irreversibly damaged. The outflow of seminal fluid and the movement of spermatozoa is prevented by obstruction of the seminal vesicles. Finally, fertility (the ability to reproduce) may be reduced as a result of infectious diseases or endocrine disorders.

diagnostic tests. In semen samples, the total number of spermatozoa, the number of normal forms and their mobility, as well as the volume of ejaculate are determined. For microscopic examination of the testicular tissue and the condition of the cells of the tubules, a biopsy is performed. The secretion of hormones can be judged by determining their concentration in the urine.

Psychological (functional) infertility. Emotional factors also affect fertility. It is believed that the state of anxiety may be accompanied by a spasm of the tubes, which prevents the passage of the egg and sperm. Overcoming feelings of tension and anxiety in women in many cases creates the conditions for successful conception.

Treatment and research. Great progress has been made in the treatment of infertility. Modern methods of hormone therapy can stimulate spermatogenesis in men and ovulation in women. With the help of special instruments, it is possible to examine the pelvic organs for diagnostic purposes without surgical intervention, and new microsurgical methods make it possible to restore the patency of the pipes and ducts.

Fertilization in vitro (in vitro fertilization). An outstanding event in the field of infertility was the birth in 1978 of the first child that developed from an egg fertilized outside the mother's body, i.e. extracorporeally. This "test-tube" child was the daughter of Leslie and Gilbert Brown, born in Oldham (UK). Her birth completed years of research work by two British scientists, gynecologist P. Steptoe and physiologist R. Edwards. Due to the pathology of the fallopian tubes, the woman could not become pregnant for 9 years. To get around this obstacle, eggs taken from her ovary were placed in a test tube, where they were fertilized by adding her husband's sperm and then incubated under special conditions. When the fertilized eggs began to divide, one of them was transferred to the mother's uterus, where implantation took place and the natural development of the embryo continued. The baby born by caesarean section was normal in all respects. After that, in vitro fertilization (literally "in glass") became widespread. Currently, such assistance to infertile couples is provided in many clinics in various countries, and as a result, thousands of "test-tube" children have already appeared.

Freezing embryos. Recently, a modified method has been proposed, which has given rise to a number of ethical and legal problems: freezing of fertilized eggs for later use. This technique, developed mainly in Australia, allows a woman to avoid repeated egg retrieval procedures if the first implantation attempt fails. It also makes it possible to implant the embryo into the uterus at the right time in a woman's menstrual cycle. Freezing the embryo (at the very initial stages of development) with its subsequent thawing also makes it possible to achieve a successful pregnancy and childbirth.

Transfer of the egg. In the first half of the 1980s, another promising method of combating infertility was developed, called egg transfer, or in vivo fertilization - literally "in a living" (organism). This method involves the artificial insemination of a woman who has agreed to become a donor with the sperm of the future father. After a few days, the fertilized egg, which is a tiny fetus (embryo), is gently washed out of the donor's uterus and placed in the uterus of the expectant mother, who carries the fetus and gives birth. In January 1984, the first child was born in the United States, which developed after the transfer of the egg.

Egg transfer is a non-surgical procedure; it can be done in the doctor's office without anesthesia. This method can help women who do not produce eggs or have genetic disorders. It can also be used for blocked fallopian tubes, if the woman does not want to undergo repeated procedures, often required for in vitro fertilization. However, a child born this way does not inherit the genes of its mother.

Bibliography

Bayer K., Sheinberg L. Healthy lifestyle. M., 1997

For the preparation of this work, materials from the site http://bio.freehostia.com were used.

The human reproductive system is a functional self-regulating system that flexibly adapts to changes in the state of the external environment and the body itself.

However, when studying the functioning of the female reproductive system, one should always remember that it is characterized by constant variability, cyclical processes, and its balance is unusually mobile. Moreover, in a woman's body, not only the state of the organs of the hypothalamic-pituitary-ovarian axis and target organs changes cyclically, but also the function of the endocrine glands, autonomic regulation, water-salt metabolism, etc. In general, almost all organ systems of a woman undergo more or less profound changes due to the menstrual cycle.

Provide a certain posture of the human body;

Move the body in space;

Move individual parts of the body relative to each other;

They are a source of heat, performing a thermoregulatory function.

The structure of the nervous system

For ease of study, the unified nervous system is divided into central (brain and spinal cord) and peripheral (cranial and spinal nerves, their plexuses and nodes), as well as somatic and autonomic (or autonomous).

The somatic nervous system mainly carries out the connection of the organism with the external environment: the perception of stimuli, the regulation of movements of the striated muscles of the skeleton, etc.

Vegetative - regulates metabolism and the work of internal organs: heartbeat, peristaltic contraction of the intestine, secretion of various glands, etc. Both of them function in close interactionhowever, the vegetative system has some independence (autonomy), managing many involuntary functions.

The spinal cord is located in the spinal canal and looks like a white cord stretching from the occipital foramen to the lower back. The cross section shows that the spinal cord consists of white (outside) and gray (inside) matter. The gray matter consists of the bodies of nerve cells and has the shape of a butterfly on the transverse layer, from the spread "wings" of which two anterior and two posterior horns depart. In the anterior horns are centrifugal neurons, from which the motor nerves depart. The posterior horns include nerve cells (interneurons), which are approached by processes of sensory neurons lying in the thickenings of the posterior roots. Connecting with each other, the anterior and posterior roots form 31 pairs of mixed (motor and sensory) spinal nerves.

Each pair of nerves innervates a specific group of muscles and the corresponding area of ​​the skin.

The white matter is formed by processes of nerve cells (nerve fibers) combined into conductive paths that stretch along the spinal cord, connecting both its individual segments to each other and the spinal cord to the brain. Some pathways are called ascending, or sensitive, transmitting excitation to the brain, others are descending, or motor, which conduct impulses from the brain to certain segments of the spinal cord.

The spinal cord performs two functions: reflex and conduction. The activity of the spinal cord is under the control of the brain.

The brain is located in the medulla of the skull. Its average weight is 1300–1400 g. After the birth of a person, brain growth continues up to 20 years. Consists of five departments; anterior (cerebral hemispheres), diencephalon, midbrain, hindbrain and medulla oblongata.

The hemispheres (the newest part in evolutionary terms) reach high development in humans, accounting for 80% of the mass of the brain.

I.P. Pavlov contrasted the concept of "higher" nervous activity with the concept of "lower" nervous activity, aimed mainly at maintaining the body's homeostasis in the process of its life. At the same time, the nerve elements that interact within the body are united by nerve connections already at the time of birth. And, conversely, nerve connections that provide higher nervous activity are realized in the process of the organism's vital activity in the form of life experience. Therefore, lower nervous activity can be defined as an innate form, and higher nervous activity as acquired in the individual life of a person or animal.

The origins of the opposition between higher and lower forms of nervous activity go back to the ideas of the ancient Greek thinker Socrates about the existence of a “lower form of the soul” in animals, which differs from the human soul, which has “thinking power”. For many centuries, ideas about the “soul” of a person and the unknowability of his mental activity remained inseparable in the minds of people. Only in the 19th century in the works of the domestic scientist, the founder of modern physiology I.M. Sechenov revealed the reflex nature of brain activity. In the book Reflexes of the Brain, published in 1863, he was the first to attempt an objective study of mental processes. Ideas I.M. Sechenov was brilliantly developed by I.P. Pavlov. Based on the method of conditioned reflexes developed by him, he showed the ways and possibilities of experimental study of the cerebral cortex, which plays a key role in the complex processes of mental activity. The main processes that dynamically replace each other in the central nervous system are the processes of excitation and inhibition. Depending on their ratio, strength and localization, the control influences of the cortex are built. The functional unit of higher nervous activity is the conditioned reflex.

In humans, the cerebral cortex plays the role of "manager and distributor" of all vital functions (IP Pavlov). This is due to the fact that in the course of phylogenetic development, the process of corticalization of functions occurs. It is expressed in the increasing subordination of the body's somatic and vegetative functions to the regulatory influences of the cerebral cortex. In the case of the death of nerve cells in a significant part of the cerebral cortex, a person turns out to be unviable and quickly dies with a noticeable violation of the homeostasis of the most important autonomic functions.

The doctrine of higher nervous activity is one of the greatest achievements of modern natural science: it marked the beginning of a new era in the development of physiology; is of great importance for medicine, since the results obtained in the experiment served as the starting point for physiological analysis and pathogenetic treatment (for example, sleep) of certain diseases of the human central nervous system; for psychology, pedagogy, cybernetics, bionics, scientific organization of labor and many other branches of human practical activity

54. A biological signal is any substance that is distinguishable from other substances present in the same environment. Like electrical signals, a biological signal must be separated from noise and transformed in such a way that it can be perceived and evaluated. Such signals are the structural components of bacteria, fungi and viruses; specific antigens; end products of microbial metabolism; unique nucleotide sequences of DNA and RNA; surface polysaccharides, enzymes, toxins and other proteins.

detection systems. To capture the signal and separate it from the noise, a detection system is needed. Such a system is the eye of a researcher conducting microscopy and a gas-liquid chromatograph. It is clear that different systems differ sharply from each other in their sensitivity. However, the detection system must be not only sensitive, but also specific, i.e. distinguish weak signals from noise. In clinical microbiology, immunofluorescence, colorimetry, photometry, chemiluminescent oligonucleotide probes, nephelometry, and assessment of the cytopathic effect of the virus in cell culture are widely used.

Signal amplification. Gain allows you to capture even weak signals. The most common method of signal amplification in microbiology is cultivation, as a result of which each bacterium forms a separate colony on dense nutrient media, and a suspension of identical bacteria in liquid media. Cultivation only needs to create suitable conditions for the growth of microorganisms, but it takes a long time. Significantly less time is required by PCR and ligase chain reaction, which allow identification of DNA and RNA, electron amplification (for example, in gas-liquid chromatography), ELISA, concentration and separation of antigens or antibodies by immunosorption and immunoaffinity chromatography, gel filtration and ultracentrifugation. Research laboratories have many methods for detecting and amplifying biological signals, but not all of them have proven their suitability for clinical microbiology.

55. Endocrine glands, or endocrine organs, are glands that do not have excretory ducts. They produce special substances - hormones that enter directly into the blood.

in men

Adenoma is a benign tumor in the region of the bladder neck. The disease is typical for older men - 50-60 years. It has several stages, the sooner it is recognized, the more you can warn yourself against complications.

This disease may not immediately make itself felt. The first symptom can be considered a minor violation of urination. This can manifest itself in a decrease in jet pressure, a person may often want to go to the toilet at night, there is a feeling that the bladder is not completely emptied. In addition, blood may appear in the urine and there may be loss of appetite, and the man is prone to constant fatigue.

All diseases of the reproductive system can be prevented by taking care of your health.

The reproductive system of a man is a complex of organs that are responsible for reproduction and procreation. The male reproductive system has a simpler structure than the female reproductive system. Specific reproductive features together characterize the sex of a person. The female and male reproductive systems have functional and anatomical differences. Those features that are most unambiguous and can be used to distinguish the sex of a particular person are called sexual characteristics.

Depending on the localization, the organs included in the reproductive system of men are divided into:

• Internal, which are located inside the body of a man.
• Outdoor.

The anatomical features of the reproductive system determine the primary signs of gender, which are laid down and formed during the prenatal period. Reproductive male system includes internal organs located in the small pelvis of a man:

1. Testicles (testicles).
2. Deferent ducts.
3. Seminal vesicles with ejaculatory ducts.
4. The prostate.
5. Bulbous (bulbar) glands.

And the genitals (penis and scrotum) are located outside. The functions of the male reproductive system are under the control of the cerebral cortex, subcortical nerve centers, lumbar and sacral spinal cord, hypothalamus and anterior pituitary gland. The anatomy of the male reproductive system determines the following functions:

• production of gametes.
• Production of testosterone and other male hormones.

The testicles (testicles) have the following structure: paired, located outside the pelvis in the scrotum - a sac-like formation of skin and a thin layer of muscle tissue. It is divided by a muscular septum into 2 sections, into which the testicles descend from the pelvic space in the second trimester of gestation. The testicles look like a slightly flattened ellipsoid.

The gonad is covered by a dense sheath of connective tissue, which, in the part facing the body, forms a roller - the testicular mediastinum. From it, thin partitions (septa) pass into the inner part of the testicles, dividing the organ into 150-280 lobules. Inside each of the lobules there are several convoluted tubules (sertoli glands), in the walls of which there are seed-forming elements that produce gametes. Between the tubules are glandular tissue cells that produce the male hormone - testosterone.

If the male germ cell has a Y chromosome, then a male organism (XY) is formed. The chromosome contains a nucleus located in the head of the spermatozoon. The structure of the sex cell of men allows it to actively move due to the tail and penetrate into the egg. The nucleus is covered with a membrane - the acrosome, which contains special enzymes that allow gametes to perform their main task - fertilization. The physiology of the reproductive function is impossible without sex hormones, which ensure the normal development of the reproductive system and are necessary for both the female and male bodies. Under their influence

1. Increases protein synthesis.
2. There is an intense increase in muscle tissue.
3. There is calcification of bones, growth of the skeleton.

The main function of the male reproductive system is the production of sperm.

Together with hormones produced by other endocrine glands, androgenic hormones ensure the reproductive health of a man - his fertility. The physiology and structure of the male phallus provide sexual intercourse, as a result of which the function of fertilization becomes possible. Sexual activity is impossible without an erection of the penis, which is a conditioned reflex and occurs in response to a complex of certain sexual stimuli.

Fertilizing abilities

The structure of the male reproductive system causes the so-called morning erections. The innervation of the entire system occurs with very close nerve endings, so the overflowing bladder has a mechanical effect on the nerve endings at the base of the penis, which leads it to an erect state without sexual stimulation.

The physiology of erection is due to the ability of the penis to increase in size. This is necessary not only to introduce the phallus into the genitals of a woman, but also to stimulate the nerve endings on the head. In this case, nerve impulses enter the nerve centers that are located in the lumbosacral region of the spinal cord. When the increased impulse exceeds the threshold of excitation, ejaculation occurs - the release of sperm into the female reproductive system.

The physiology of the male reproductive system is normally designed to clearly perform the function of continuing the species. At one time, 2-8 ml of semen is ejected, which contains 120 million spermatozoa. This makes up only 5% of the contents of the ejaculate, the remaining 95% is accounted for by the secretion of the glands of the reproductive system. In order to ensure a high level of fertility, it is necessary that more than 55% of spermatozoa be of normal morphology and more than half have high motility.

The main function of the male reproductive system is to continue the species.

Anatomically, the human reproductive system is designed in such a way as to minimize the path that the cell needs to go through, but at the same time, its physiology ensures that the egg is fertilized only with high-quality material. So, for example, the reproductive function of a man is impossible without:

• The normal operation of the selection system for healthy and active spermatozoa in the epididymis.
• The functioning of the glands that produce a secret that neutralizes the acidic environment of the woman's vagina.
• The level of hormonal background, which provides neurohumoral regulation of the process.

The lifespan of a sperm cell in a woman's genital tract is 2 days. The reproductive physiology of the system has conditioned the production of such a large amount of sperm to increase the chance of a single sperm to overcome obstacles on the way to the egg. The energy reserve for spermatozoa is enough for 12-24 hours of active movements, and although they remain viable for another day, they will no longer be able to fertilize the egg.

The video shows the difficult journey that a spermatozoon needs to go through in order to fulfill its reproductive purpose. From the point of view of physiology, you can improve the fertility of a man with the help of:

• Stimulation of testosterone production.
• introducing it into the body.

You can increase the activity of spermatozoa and improve the quality of sperm by taking vitamin and mineral complexes and normalizing your lifestyle. But not only physiology affects the process of ejaculation and erection. The psycho-emotional state is of great importance. For example, the intake of hallucinogenic mushrooms increases spermatogenesis and increases libido, as they affect the physiology of the reproductive system, increasing the susceptibility of receptors.

And the psychedelic surroundings, music or colors, on the contrary, have a depressing effect on the physiology of a man. However, physiology alone cannot explain the sexual attractiveness of some female phenotypes. Therefore, the psychological component is an important component in the normal functioning of the reproductive system. The physiology and structure of the male reproductive organs is the minimum knowledge necessary for any man in order to avoid the development of pathology or a decrease in the function of one of the most important systems in human life.

The female reproductive system is quite complex. So in the structure of the female reproductive system, external and internal genital organs are distinguished. The first include small and large labia, pubis and clitoris.

The labia are 2 pairs of skin folds that cover the entrance to the vagina and perform a protective function. Above, at the point of their junction, is the clitoris, which in its structure is completely similar to the male member. It also increases in size during sexual contact and is the erogenous zone of a woman. The totality of the organs and formations listed above is called the vulva.

The internal organs that make up the reproductive system of a woman are completely surrounded on all sides by the bones of the pelvis. These include:

• 2 ovaries;
• uterus with tubes;
• vagina.

The uterus is located exactly in the center of the pelvis, behind the bladder and in front of the rectum. It is supported by double elastic ligaments that keep it permanently in one position. It is a hollow, pear-shaped organ. Its walls in its composition contain a muscle layer, which has a great contractility and extensibility. That is why the uterus increases significantly in size during pregnancy, as the fetus grows. Restoring it after childbirth to its original size occurs in 6 weeks.

The cervix is ​​an extension of her body. This is a narrow, thick-walled tube that leads to the top of the vagina. The cervix communicates the uterine cavity with the vagina.

The vagina in its structure resembles a tube, the average length of which is 8 cm. It is through this channel that sperm enter the uterus. The vagina has great elasticity, which gives it the ability to expand during the birth process. Thanks to a well-developed network of blood vessels, the vagina swells a little during intercourse.

The tubes are where the sperm meets the egg after ovulation. The length of the fallopian tubes is about 10 cm. They end with a funnel-shaped extension. Their inner walls are completely covered with ciliated epithelium cells. It is with their help that the mature egg moves to the uterine cavity.

The ovaries are part of the female endocrine system and are glands of mixed secretion. They are usually located below the navel in the abdominal cavity. It is here that the formation of eggs and their maturation takes place. In addition, they synthesize 2 hormones that have a huge impact on the body - progesterone and estrogen. Even at birth, about 400 thousand eggs are laid in the ovaries of a girl. Every month, throughout the woman, 1 egg matures, which enters the abdominal cavity. This process is called ovulation. If the egg is fertilized, pregnancy occurs.

In order to avoid the development of diseases, every woman should know how her reproductive system works. Diseases of the female reproductive system are quite diverse and in many cases are the cause of infertility.

Often, the development of anomalies of the reproductive system of a woman can be observed. As a rule, this happens during embryogenesis. Examples of such anomalies include vaginal agenesis, cervical agenesis, uterine agenesis, tubal agenesis, and other defects.

The female reproductive system: structure and physiology

In a woman, the most important role in the reproductive process is played by the uterus, ovaries and fallopian (uterine) tubes (Fig. 1).

ovaries, small oval-shaped organs located on both sides of the uterus, under the fallopian tubes. They contain immature eggs - cells, the fertilization of which by spermatozoa leads to the birth of a fetus. All eggs are produced in a woman's body before she is born. The maturation of eggs in the ovaries occurs throughout almost the entire subsequent life of a woman - from the end of puberty to the end of the reproductive period. Every woman has a monthly ovulation- one of the eggs reaches full maturity and leaves the ovary. After leaving the ovary, the “chosen” egg enters the fallopian tube, along which it moves to the uterus.

Fallopian (uterine) tubes, or oviducts, is a paired organ that connects the uterine cavity with the abdominal cavity in the region of the ovaries. The total length of one fallopian tube is usually 10–12 cm.

The fallopian tubes are quite complicated, and, accordingly, they have several functions. Capturing a mature egg as it leaves the ovary, they provide it with sufficient nutrition and move it towards the uterus.

On the other hand, the fallopian tubes help the sperm to move towards the egg, thus creating a favorable environment for fertilization. About a day after ovulation, the egg reaches the expanded part of the tube, the so-called ampoules where fertilization takes place. Further along the oviduct, the already fertilized egg (zygote) moves to the uterus. This is the mechanism of "correct" fertilization.

fertilized egg, or embryo, within a few days moves through the tube into the uterine cavity to attach to its inner surface (endometrium).

Uterus is a hollow pear-shaped organ located in the lower part of the pelvis of a woman. After ovulation, the lining of the uterus (endometrium) begins to grow to prepare for possible embryo attachment. If fertilization occurs and the embryo is successfully fixed in its place, the endometrium provides protection, development and nutrition of the fetus until its birth. Otherwise, the endometrium is shed and removed from the uterus during menstruation.

The part of the uterus that protrudes into the vagina is called cervix. The cervix produces a so-called cervical mucus, the amount and composition of which varies depending on the phase of the menstrual cycle. During the period of ovulation, that is, on the days most favorable for conception, the amount of cervical mucus released from the vagina increases markedly. These days it is thin and watery, which makes it easier for sperm to enter the uterine cavity. By the way, it is cervical mucus that contributes to the death of a significant number of spermatozoa that have certain abnormalities, which increases the chances of having healthy offspring.

After ovulation and during pregnancy, the mucus becomes thick and viscous, protecting the body from infection.

Features of the menstrual cycle

A woman's menstrual cycle is the period from the first day of her period to the day before her next period. A large number of hormones and internal organs are involved in this complex process.

On the first day of the menstrual cycle, the pituitary gland begins to produce follicle-stimulating hormone (FSH). FSH ensures the growth of follicles in the ovary and the production of the female sex hormone - estrogen.

Around the fourteenth day of the cycle, the pituitary gland releases large amounts of another substance called luteinizing hormone (LH). LH stimulates the maturation of one of the eggs and its release from the ovary, that is, ovulation. It is this day of the cycle that is most favorable for conception.

As the egg travels down the fallopian tube, the follicle in the ovary begins to produce another hormone called progesterone. Progesterone prepares the uterus and endometrium to meet the embryo.

The life span of an egg is 24 hours. It is during this time that the egg can be fertilized by the sperm in the fallopian tube. The resulting embryo follows the tube into the uterine cavity, where it will attach to the endometrium and begin to develop.

If fertilization does not occur, the egg will pass into the uterine cavity, where it will degenerate. Approximately 2 weeks after ovulation, the ovaries will stop producing progesterone, resulting in endometrial detachment and menstrual bleeding. After that, the whole cycle will repeat from the beginning.

The menstrual cycle lasts an average of 28 days, but this is not typical for all women. It is very important to know exactly how long your cycle is. If its duration varies significantly from month to month, then you should consult a doctor to find out the cause.