Neuroendocrine regulation of the reproductive system. Age periods of a woman's life
M-o cycle- this is a complex of complex cyclically repeating processes in the reproductive system and in the body of a woman as a whole, aimed at reproduction. Duration - from the first day of the previous menstruation to the first day of the next (21-35 days). In the reproductive system, women secrete 5 levels: 1. target organs and tissues (genital organs, mammary gland, skin, hair, fat and bones) 2. ovaries 3. anterior pituitary gland 4. hypophysotropic lobe of the hypothalamus 5. extrahypothalamic structures of the brain (limb c, hippocampus, almonds body ). First level - tissues have cytosol receptors for sex steroid hormones (estradiol, progesterone, testosterone). The most pronounced changes occur in the structure of the endometrium, a successive change 4 phases: 1. desquamation 2. regeneration 3. proliferation 4. secretion. With a sharp decrease in the level of estrogens and gestagens, a spasm of the vessels that feed the functional layer occurs. The necrotic and blood-soaked functional layer is rejected (desquamation). Day 2-3 of menstruation (regeneration) - restoration of the functional layer due to the elements of the basal layer. 5-14 days (proliferation) - under the influence of estrogens, the functional layer grows up to 10 mm. (secretion) - + progesterone, proliferation is inhibited, secretory formations appear. 1) accumulation of glycogen in basal vacuoles, 2) separation of f.s. on the compact (above) and spongy (deep) layers. Intensive growth of spiral arteries, sinusoids appear in the compact layer. 3) an increase in degenerative changes, a deterioration in blood supply. Second level: follicular apparatus (ovaries). Stages of development of the dominant follicle. Primordial f consists of an ovum surrounded by 1 layer of compacted cells of follicle epithelium. In the process of maturation, the ovum increases in size, epite cells multiply and round (granular layer fall). In the thickness of this layer, as a result of cell breakdown, a transudate is formed, which pushes the egg to the periphery. The egg is surrounded by 17-50 rows of granulosa cells (oviferous mound). In the Graaffian vesicle, the eggs are surrounded by a vitreous membrane. The stroma around the follicle is the outer and inner lining of the follicle. The ripening foll turns into a mature one. In the follicular fluid, increase the content of estradiol and the follicle-stimulating hormone - the release of luteinizer hormone - ovulation. Collagenase and prostaglandins ensure the rupture of the follicle. A corpus luteum forms at the site of the ruptured follicle - it secretes progesterone. Third level: the anterior lobe of the pituitary gland secretes: FSH, LH, PrL, etc. The target gland for LH and FSH is the ovary. FSH stimulates follicle growth, proliferation of cells of granulosa, formation of LH cells on top of cells of granulosa. LH stimulates the formation of androgens in theca cells and the synthesis of progesterone in the cells of the corpus luteum. Prolactin - stimulates the growth of the mammary glands and regulates lactation. Fourth level: hypothalamus-ventromedial, dorsolateral and arcuate nuclei. They secrete gonadotropic-releasing hormone (GT-RG). Arcuate nuclei - axons - terminal endings - capillaries medial elevated hypothalamus - pituitary gland. Fifth level: cerebral structures, perceiving impulses from the external environment and from interoreceptors, transmit them through the system of neurotransmitters to the neurosecretory nuclei.
3. . Syndrome of respiratory disorders. Classification, clinic, diagnosis, treatment , obstetric tactics.
A pathological condition that develops in premature babies in the first hours and days of life and is associated with a lack of function of the surfactant system of the lungs.
Causes:
Deficiency in the formation and release of surfactant - a qualitative defect in the surfactant - inhibition and destruction of the surfactant - immaturity of the structure of the lung tissue
Risk factors:
Prematurity, intrauterine infections, perinatal hypoxia and asphyxia and the lung ischemia and acidosis caused by them, DM in the mother, acute blood loss during childbirth, planned caesarean section. More often occurs in children with: intragastric hemorrhages and periventricular lesions, transient hypofunction of the thyroid gland and adrenal glands, hypovolemia, hyperoxia, with general cooling, in the second twin of twins.
Classification:
By etiology:
hypoxic, infectious, infectious-hypoxic, endotoxic, genetic genesis. By severity:
I (mild degree) - in relatively mature children who have a moderate condition at birth. Symptoms develop only with functional loads: feeding, swaddling, manipulation. RR less than 72 per minute; the gas composition of the blood is not changed. The condition of the newborn is normalized within 3-4 days.
II (moderate degree) - the child is born in a serious condition that requires resuscitation. Signs develop within 1-2 hours after birth and persist for up to 10 days. The need for oxygen supplementation usually disappears on the 7-8th day of life. Against the background of the syndrome, every second child has pneumonia.
III (severe degree) - in immature and very premature babies. Signs of a syndrome of respiratory disorders (hypoxia, apnea, areflexia, cyanosis, severe depression of the central nervous system, impaired thermoregulation) from the moment of birth. There is tachycardia or bradycardia, arterial hypotension, signs of myocardial hypoxia on the ECG. Great lethal outcome.
Clinic and diagnostics:
Prenatal diagnosis:
assessment of the maturity of the lungs of the fetus by the phospholipid composition of the amniotic fluid and the assessment of the level of surfactant protein A.
For a newborn:
Shortness of breath (60 breaths / min), against the background of pink skin, hypoxemia with PaO2 blood 65 mm Hg. Cyanosis with PaO2 covi 32-44 mm Hg.
Expiratory noises (grunting breath)
Retraction of the chest on exhalation; later, tension of the wings of the nose, apnea attacks, cyanosis, pallor of the skin, swelling of the cheeks, rigid heart rate, paradoxical breathing (retraction of the anterior abdominal wall on inspiration), foam at the mouth, swelling of the hands and feet, flat chest occur. - auscultatory: weakened breathing, against the background of mechanical ventilation - normal respiratory noises, later - dry rales on inhalation and exhalation, crepe and small bubbling rales.
General symptoms: hypothermia, lethargy, poor movements, hyporeflexia, lethargy and coma, arterial and muscular hypotension, oliguria, regurgitation, bloating, signs of intestinal obstruction, periphedema, large body weight loss. The lower limbs are in the frog pose.
extremely severe form of SDR - 10 points Severe - 6-9 points moderate - 5 points
beginning SDR - less than 5 points.
Violations in the CCC: tachycardia, muffled tones, pulmonary hypertension and hypovolemia, blood clotting, increased hematocrit, increased hemoglobin; hypoxia increases, congestion in the lungs, pulse pressure increases, systole-diastolic murmur on the vessels.
Complications: patent ductus arteriosus, septic shock, disseminated intravascular coagulation, hemorrhage, hypoglycemia, transient hyperammonemia, kernicterus; air leakage syndrome, hemorrhages in the lungs, pneumonia, bronchopulmonary dysplasia.
X-ray: diffuse foci of reduced transparency, air bronchogram, reduced pneumatization of lung fields in the lower parts of the lungs and at the tops; decreased lung volume, cardiomegaly and disseminated atelectasis.
Monitor observation: control of heart rate and respirations; transcutaneous oxyhemoglobinometry; every 3-4 hours, the temperature of the skin of the abdomen, blood pressure, diuresis, CBS, the level of glycemia and the concentration of oxygen in the inhaled air; X-ray of OKG; KLA, blood culture and tracheal contents, hematocrit determination; determination of serum urea, potassium, sodium, calcium and magnesium, total protein and albumin, blood osmolarity.
Treatment:
Temperature protection (in a heated diaper, under a heat source and in a pitcher)
Maintenance of airway patency (tracheal intubation and suction of the contents of the respiratory tract) - infusion therapy (30-40 minutes after birth, inf therapy begins: the volume of fluid on the first day is 50-60 ml / kg, in the last days we increase by 20 ml / kg; in the first day - glucose, from the second - sodium, chlorine, potassium and calcium)
Nutrition (with a decrease in shortness of breath to 60 per minute, no apnea, regurgitation) -normalization of the gas composition of the blood (moisturizing and heating of oxygen is mandatory) -correction of KOS -antibiotics (penicillin in combination with aminoglycoside-gentamicin)
Vitamin therapy (E 10 mg / kg for 10 days, A 2000 units every other day) - diuretic (furosemide, only for pulmonary edema)
Surfactant replacement (surfactant from amniotic fluid of pregnant women, during cesarean, from the lungs of cattle, sheep, pigs, synthetic surfactants)
Effective introduction of surfactant at birth or in the first 15 minutes of life (deadline 6-8 hours)!!!
Obstetric tactics:
With the threat of termination of pregnancy at 28-34 weeks, 3 days before delivery, 6 mg of betamethasone or 12 mg of dexamethasone are administered every 24 hours (the risk of developing an open arterial duct, intrazhel hemorrhages, necrotizing enterocolitis and bronchopulmonary dysplasia is reduced).
Prolongation of labor (when the anhydrous period lasts more than 2 days, SDR does not develop!) - the introduction of thyrotropin releasing hormone into the amniotic fluid.
Ticket 7
1.Features of the course of pregnancy and childbirth in multiple pregnancies.
Etiology and pathogenesis. Hereditary factors - through the mother (7.5%) or father (1.7%). A multiple pregnancy is the result of the fertilization of several eggs, or two or more embryos develop in a fertilized egg. Dizygotic twins - 2 amniotic, chorionic membranes and 2 placentas; Monozygotic twins - 2 amniotic
1 chorionic and 1 placenta. Diagnostics. In the first trimester - only on ultrasound, in the second - due to the size of the uterus, exceeding the expected period. In the 3rd trimester - a discrepancy between the circumference of the abdomen and the height of the fundus of the uterus to the term and size of the head. Coolant - more than 100 cm, standing height of the bottom - more than 40 cm. Ultrasound - the accuracy of multiple pregnancy and the size of the fetus. CTG - the state of the fetus. The course of pregnancy. Even with a favorable tech-stationary observation for 28-30 weeks (anomalies in the position of the fetuses, early toxicosis, polyhydramnios of one of the twins, developmental delay of one b, the threat of abortion). Re-hospitalization in the antenatal department 2-3 weeks before the term. The course of childbirth. Complications: premature birth, weight of newborns not higher than 2500 g, both or one fetus in breech presentation or transverse position, early outflow of water, weakness of labor, premature detachment of a normally located placenta. Childbirth through the natural path is possible only with twins (under monitor control: CTG). In urgent delivery, intravenous administration of prostaglandin F 2α or oxytocin is carried out. After the birth of the first fetus, there is a pause of 4-5 minutes (an external obstetric examination is performed, an examination of 2 fetuses), then the contractions resume and the doctor opens the amniotic sac. Indications for caesarean section: triplets or more, transverse position of the fetus, breech presentation of both or the first fetus, polyhydramnios (fetal hypoxia, prolapse of the umbilical cord, persistent weakness of the childbirth).
In the regulation of the reproductive system, I single out 5 levels that act on the principle of direct and feedback due to the presence of receptors for sex and gonadotropic hormones in all links of the chain.
The first (highest) level of regulation are: the cerebral cortex, the hypothalamus and extrahypothalamic cerebral structures, the limbic system, the hippocampus, the amygdala. In these structures, specific receptors for sex hormones have been isolated. In response to external and internal stimuli, synthesis and release of neurotransmitters and neuropeptides occur in the cortex and subcortical structures, which primarily affect the hypothalamus, promoting the synthesis and release of releasing hormone.
The cerebral cortex secretes endogenous opioid peptides (EOPs): enkephalins, endorphins and dynorphins, which affect the hypothalamus.
Cerebral neurotransmitters regulate the production of gonadotropin-releasing hormone (GnRH - stimulates the production of LH and FSH): NA, ACh and GABA stimulate their release, and dopamine and serotonin have the opposite effect.
Neuropeptides(EOPE, corticotropin-releasing factor and galanin) also affect the function of the hypothalamus and the balance of the functioning of all parts of the reproductive system.
The second level of regulation of the reproductive system is hypothalamus, in which stimulating (liberins) and blocking (statins) neurohormones are secreted. The hypothalamus secretes GnRH containing RGFSH (folliberin) and RHLG (luliberin), which act on the pituitary gland.
GnRH secretion is genetically programmed and has a pulsatile (circhoral) character: peaks of increased hormone secretion lasting several minutes are replaced by 1-3-hour intervals of relatively low secretory activity. The frequency and amplitude of GnRH secretion in the preovular period against the background of the maximum release of estradiol is much greater than in the early follicular and luteal phases.
The third level of regulation is the anterior lobe of the pituitary gland ( adenohypophysis), in which FSH (follitropin), LH (lutropin), prolactin (PrL), ACTH, STH, TSH (thyroliberin) are synthesized. FSH, LH and PrL act on the ovary. PrL stimulates the growth of the mammary glands and lactation, controls the secretion of progesterone by the corpus luteum by activating the formation of LH receptors in them.
The synthesis of PrL by the adenohypophysis is under the tonic blocking control of dopamine (prolactin inhibitory factor). Inhibition of PrL synthesis stops during pregnancy and lactation. The main stimulator of PrL synthesis is TSH synthesized in the hypothalamus.
The remaining hormones of the pituitary gland affect the endocrine glands corresponding to their name. Only with a balanced release of each of the pituitary hormones is the normal function of the reproductive system possible.
The fourth level of regulation includes peripheral endocrine organs (ovaries, adrenal glands, thyroid gland).
The fifth level of regulation consists of the internal and external sections of the reproductive system (uterus, fallopian tubes, vaginal mucosa), which are sensitive to fluctuations in the levels of sex steroids, as well as the mammary glands. The most pronounced cyclic changes occur in the endometrium.
The cyclicity of the system that regulates the reproductive function is determined by direct and feedback between the individual links. Example: FSH, through receptors in ovarian follicular cells, stimulates the production of estrogen (feed-forward). Estrogens, accumulating in large quantities, block the production of FSH (feedback).
In the interaction of the links of the reproductive system, “long”, “short” and “ultra-short” loops are distinguished. The “long” loop is the effect through the receptors of the hypothalamic-pituitary system on the production of sex hormones. "Short" - determines the connection between the pituitary gland and the hypothalamus, "ultrashort" - the connection between the hypothalamus and nerve cells that carry out local regulation using neurotransmitters, neuropeptides, neuromodulators and electrical stimuli.
2.Discoordinated labor activity (DRD). Clinic, differential diagnostics, treatment and prevention.
These forms of labor anomalies have different clinical manifestations and names:
Contraction ring, cervical dystocia;
Discoordination of labor activity;
Contraction of the uterus in the form of an "hourglass";
Hypertensive dysfunction of the uterus;
Uncoordinated activity of the uterus;
Uterine dystocia
A common factor is hypertonicity of the myometrium, against which the contractile activity of the uterus is distorted.
Hypertensive disorders of the contractile activity of the uterus are more common than the weakness of generic forces, but are less commonly diagnosed. Their forms are more diverse in clinic and mechanism of development and are difficult to recognize.
Pathogenesis hypertensive dysfunction of uterine contractions is a violation of the functional balance of the autonomic nervous system. In this case, there may be a decrease in the function of the sympathetic-adrenal and the predominance of the tone of the parasympathetic (cholinergic) subsystem; overexcitation of both departments or only the cholinergic part leads to the development of a condition that can be compared with parabiosis.
The principle of operation of autonomic innervation differs from that of the animal nervous system. All processes occurring in the uterus are only regulated by the autonomic nervous system (ANS), but are not completely subordinate to it. Contractions of the uterus (automatism of labor activity) can occur when the vegetative influence is disturbed and even turned off. In addition, the ANS acts in close collaboration with humoral regulation and the necessary degree of hormonal saturation of the genital tract tissues.
The Schikkele Phenomenon- weak contractions of the body of the uterus and strong contractions of the cervix.
Causes DRD:
- Violations of the functional balance of the ANS (vegetative neurosis, overwork)
2. Pathology of the myometrium and cervix (malformations and hypoplasia of the uterus, inflammatory and cicatricial changes in the uterine wall (endometritis, cervicitis, DEC, etc.), "hard" cervix in nulliparous > 30 years old)
3. The presence of a mechanical obstacle in childbirth (narrow pelvis, incorrect position of the fetus, dense fetal membranes, low-lying myomatous node)
4. Excessive overstretching of the uterus (large fetus, polyhydramnios, multiple pregnancies)
5. Fetoplacental insufficiency
Violation of the structure of the placenta (delayed, premature, dissociated)
Inflammation of the aqueous and decidual membranes (chorioamnionitis, basal endometritis)
Fetal pathology (anencephaly, hypoplasia and aplasia of the ovaries)
6. Neuroendocrine and somatic diseases of the mother with hormonal disorders
Neuroendocrine disintegration
Hypoestrogenism
7. Decrease in the protective effect of the anti-stress system of the brain (decrease in the production of neurohormones (endorphins, enkephalins, dynorphins), which occurs with anxiety, general muscle tension)
8. Iatrogenic causes (incorrect assistance to a woman in labor, the appointment of labor induction or labor stimulation in the absence of indications, inadequate labor pain relief, leading to spastic muscle contraction, untimely amniotomy of a flat fetal bladder)
Main clinical symptoms, preceding DRD:
1. Immature cervix at full-term (39-40 weeks) pregnancy, which remains so even with the onset of labor
2. The presence of a pathological preliminary period
3. Premature discharge of water with an "immature" neck and a small opening of the cervical canal
4. Lack of pressing and fixation of the pre-burning part before childbirth and with the onset of contractions
5. Palpation of the uterus in the form of an elongated ovoid and tightly covers the fetus
6. Oligohydramnios, often in combination with FPI
Symptoms DRD:
1. Contractions uneven in frequency, strength and duration. Occur after 1-2-5-3-7-1 minutes; the amplitude of contractions is sometimes reduced (20-25 mm Hg), sometimes it increases sharply (60-70 mm Hg)
2. There is a sharp pain in contractions (like a spasm). The behavior of the woman in labor is restless, she asks for anesthesia even in the latent phase
3. Between contractions, the uterus does not relax. Due to the hypertonicity of the lower segment, palpation of the presenting part is difficult
4. Difficulty urinating occurs (with full proportionality of the head and pelvis)
5. Characteristic is the slowdown in the shortening and smoothing of the cervix - the latent and active phases of labor lengthen
- The synchrony of fetal advancement is disturbed. The presenting part stands for a long time in each plane, as is the case with a narrow pelvis.
- Often there is a violation of the biomechanism of childbirth due to hypertonicity of the lower segment or individual zones of the uterus
- DRD is accompanied by impaired uteroplacental and fetal-placental blood flow
- Premature early attempts are possible, not only as a result of infringement of the cervix between the head and pelvis, but also as a result of prolonged spasm, swelling of the cervix and vagina
- Early formation of a generic tumor on the presenting part. Corresponding to the place of infringement by a spastically reduced uterine os even with a small (5 cm) opening
- The characteristic symptom and complication is active cervical dystocia.
- The presence of a flat membrane
- Early outflow of water with an unsmoothed cervix and a dilatation of 1.5-2 cm.
- Characteristic for DRD are autonomic disorders varying degrees of severity: nausea, vomiting, bradycardia or tachycardia, hypertension or hypotension, VVD, pallor or flushing of the face, sweating, increased t to 38 degrees C and above, chills, etc.
- Complications are of particular risk in DID, such as uterine rupture, which in such cases is possible even in primiparas with OGA; massive heavy bleeding in the afterbirth and early postpartum periods, due to a combination of the pathology of uterine contraction and the development of coagulation pathology (DIC).
DRD 1 degree of severity. There is an overexcitation of the ANS (sympathetic and parasympathetic), but with the preservation of the dominant sympathetic-adrenal system. During vaginal examination, attention is drawn to the compaction and tension of the thickened edges of the cervix during contractions. Manifestations: The triple downward gradient is retained. The force of the contraction of the upper segment prevails over the contractions of the isthmus. Contractions are frequent. Prolonged pain. Structural changes in the cervix do not occur gradually, but sometimes slowly, sometimes too quickly. The uterine pharynx opens not only due to increased stretching of the circular muscles, but also due to ruptures and tears, inevitable in this pathology. The fetal bladder has a flat shape, the membranes are dense, there are few anterior waters, a moderately pronounced tension of the bladder remains outside the contractions. With amniotomy or spontaneous outflow of o / pl. water, contractile activity of the uterus and myometrial tone can be normalized. Contractions gradually become more regular and effective. Childbirth may end normally, but there will be ruptures of the birth canal. There are vegetative disorders: nausea, vomiting when opening the cervix, difficulty urinating, tachycardia, possible hyperthermia in childbirth.
Complications: disturbances in the processes of separation of the placenta, early postpartum hypotonic bleeding, the development of hypoxic-ischemic disorders of the central nervous system in newborns, which are leveled only by 3-5 days after birth.
DRD 2 severity (spastic segmental dystocia of the uterus).
This is the second, more severe degree of incoordination and contraction of the uterus. It occurs either independently, if the initial autonomic disorders are deeper, or is an aggravation of the previous degree with irrational management of childbirth. Despite prolonged labor activity (8-10 hours or more), the cervix remains dense, long, the internal os is defined as a dense roller. Due to the spastic contraction of the internal os and insufficient deployment of the lower segment of the uterus, the presenting part remains mobile for a long time above the entrance to the small pelvis. The basal tone rises to 14-20 mm. The outpouring of water does not change the spastic nature of the contractions. Often, the rupture of the membranes goes unnoticed due to the lack of anterior waters.
Segmental dystocia differs from DRD I degree by the predominance of spasm of the circular muscles not only in the area of the internal pharynx, but also in the higher lying sections - the lower segment. Spasm of the circular muscles in the lower segment leads to "hanging neck dystocia" (the external os is significantly dilated, the internal os is spastically contracted). Perhaps the appearance of a clinic of a narrow pelvis (violations of the biomechanism of childbirth, "hourglass" with incomplete opening of the uterine os with low localization, with bladder pressing). Pronounced signs of autonomic dysfunction (hyperemia of the face, vomiting, sweating, dry mucous membranes, tongue, hyperthermia up to 38-39C).
Complications: embolism with amniotic fluid, premature detachment of the placenta, rupture of the defective myometrium in OAHA (aggravated obstetric and gynecological history), the development of birth shock. For the fetus: "lacing compression of the uterus" with damage to the organs at the level of which it occurs, aspiration of amniotic fluid, hypoxic-traumatic damage to the central nervous system.
DRD grade 3 (spastic total dystocia of the uterus). Total prolonged spasm of the circular muscles of the cervix, uterine body, tubal angle, vagina (pacemaker displacement in the vertical and horizontal). The uterus is divided into several zones, each contracting in its own rhythm, amplitude and frequency. There is fibrillation of the myometrium, similar to the flickering of the heart. All muscle fibers, especially circular ones, are in a state of tonic tension. The total effect of the action is extremely low and therefore labor slows down and stops. Contractions become rare, short, weak in contrast to the true weakness of labor activity, myometrial hypertonicity persists. The clinical picture of the transition of DRD to the hypertonic form of weakness is very characteristic.
A clinic similar to the torpid phase of shock develops - pallor and marbling of the skin, acrocyanosis, frequent soft pulse. In the bladder, in the absence of independent urination, there is a small amount of urine with a high content of L, Er, cylinders. After spastic, very painful contractions, a period of visible weakening of labor activity begins. The woman in labor no longer screams, and does not rush about, but complains of constant dull pains in the sacrum and lower back. This often leads to an erroneous diagnosis of "secondary weakness" with subsequent delivery, which is categorically contraindicated in this pathology.
During vaginal examination, the tense muscles of the pelvic floor, edematous, thick edges of the uterine os are noteworthy, the degree of opening of the uterine os is reduced. In comparison with the previous study, it seems that the opening of the uterine os not only does not progress, but becomes smaller.
It is difficult to determine the integrity of the fetal bladder, because of the dense membranes that are literally stretched over the head. There is a pronounced birth tumor, which can reach the pelvic floor and causes futile attempts.
Spontaneous restoration of normal contractile activity without medical correction is almost impossible. In parturient women, body t rises rapidly, chorionamnionitis and metroendometritis develop, worsening the prognosis of the outcome of childbirth for the mother and fetus.
Therapy: before conducting labor through the natural birth canal and applying corrective therapy, it is necessary to compare risk factors for the mother and fetus, anamnesis, assess the proportionality of the fetal head and mother's pelvis, as well as the condition of the fetus, in order to decide on the advisability of expanding the indications for caesarean section .
3. Task: The back of the fetus is left anterior. The head is motionless, most of it is above the entrance to the pelvis, a small segment of the head is below the plane of the entrance to the pelvis. During vaginal examination: the sacral cavity is free, the promontory can be approached with a bent finger (if it is achievable). The inner surface of the symphysis is available for research. Sagittal suture in transverse or slightly oblique (right) size, small fontanel on the left below the large one.
EXAM TICKET 13
3. Hormones in the ovaries, their biological effects in organs and tissues.
· Estrogens - (from oestrus - estrus), (estradiol, estrone, estriol). Under the influence of estrogens, girls develop secondary sexual characteristics in the form of a distribution of the subcutaneous fat layer typical for women, a characteristic shape of the pelvis, enlargement of the mammary glands, growth of pubic and axillary hair. Estrogens promote the growth and development of the reproductive organs, especially the uterus; under their influence, growth of the labia minora, elongation of the vagina and an increase in its extensibility occur, and the nature of the secretion of the glands of the cervical canal changes, proliferation of the endometrium and vaginal epithelium occurs, etc. Estrogens have a significant effect on metabolic processes and thermoregulation. Under the influence of estrogens, the metabolism proceeds with a predominance of catabolism (delay in the body of sodium and water, increased dissimilation of proteins), and a decrease in body temperature, including basal (measured in the rectum), is also observed.
· Gestagens (from gesto - to wear, to be pregnant) (progesterone), contribute to the normal development of pregnancy. Progestogens, produced mainly by the corpus luteum of the ovary, play an important role in the cyclic changes in the endometrium that occur in the process of preparing the uterus for implantation of a fertilized egg. Under the influence of gestagens, the excitability and contractility of the myometrium are suppressed while increasing its extensibility and plasticity. Gestagens, together with estrogens, play an important role during pregnancy in preparing the mammary glands for the upcoming lactation function after childbirth. Under the influence of estrogens, the proliferation of milk passages occurs, and gestagens act mainly on the alveolar apparatus of the mammary glands. Gestagens, in contrast to estrogens, have an anabolic effect, i.e., they contribute to the absorption (assimilation) of substances by the body, in particular proteins, coming from outside. Along with the above anabolic effect, gestagens cause a slight increase in body temperature, especially basal.
· Androgens (from andros - man), or male sex hormones, in excess cause a woman to show signs of masculinity, or masculinization. Androgens, produced in small amounts by the ovaries in the hilus cells, promote the growth of axillary and pubic hair, as well as the development of the clitoris and labia majora. Androgens, like gestagens, have anabolic properties.
The cerebral cortex, hypothalamus, pituitary gland, ovaries, uterus take part in the regulation of the menstrual cycle. Violation of each of the links of regulation can lead to a disorder of menstrual function.
The connection between the hormones produced during the menstrual cycle and the central nervous system is natural: after castration or as a result of changes in the secretion of sex hormones, the functional activity of the cerebral cortex is weakened.
The special role of the hypothalamus in the regulation of the menstrual cycle became clear after it was found that it secretes specific neurosecretory substances (releasing factors - RF) that stimulate or inhibit the production of gonadotropic hormones of the pituitary gland. Thus, the hypothalamus is the center of the nervous system, which regulates the cyclic activity of the pituitary gland, and hence the ovaries. Currently, it has been shown that there are centers of the hypothalamus responsible for the constant, or tonic, secretion of pituitary gonadotropins, located in the region of the arcuate and ventromedial nuclei, and centers that provide a rapid release of gonadotropins, located in the preoptic region. Ovulation requires cyclic RF secretion.
Recent studies have made it possible to isolate some RFs from the hypothalamic tissue and establish their chemical structure. Various analogs of luteinizing RF (LRF) have been synthesized, which have high biological activity and have a therapeutic effect in clinical use.
RF of luteinizing and follicle-stimulating hormone cause the production of LH and FSH, and the factor found in the hypothalamus, which regulates the secretion of LTH, has inhibitory properties (IF).
Changes in the function of the hypothalamus lead to menstrual dysfunction, which is mainly associated with a violation of the production of pituitary hormones.
The pituitary gland plays an important role in the regulation of the menstrual cycle, the hormones of its anterior lobe directly affect the ovaries, causing ovulation. Disturbances in the secretion of gonadotropic hormones are associated with diseases such as Sheehan's syndrome, Chiari-Frommel's syndrome, which cause severe ovarian dysfunction.
The ovaries produce those steroid hormones that directly cause ovulation - estrogen and progestin. Ovarian dysfunctions, both primary, caused by a change in the tissue that produces steroids, and secondary, associated with damage to the hypothalamic-pituitary region, are most often the cause of changes in ovulation processes, as well as menstrual cycle disorders.
Ovarian hormones cause changes in the lining of the uterus (uterine cycle) that lead to menstruation. However, if the reception of the endometrium is disturbed or it is damaged by an inflammatory process, the uterine form of amenorrhea occurs.
The feedback principle turned out to be effective not only for the hormones of the hypothalamus-pituitary, pituitary-ovaries system, but also for the ovaries-hypothalamus system. The increased content of blood estrogen suppresses the production of FSH - RF.
The mechanism of the ovulatory cycle consists of a series of changes in the secretion of RF, gonadotropins and sex steroid hormones.
Schematically, the menstrual cycle occurs as follows. FSH - RF is secreted in the hypothalamus, which stimulates the secretion of FSH from the pituitary gland. FSH stimulates the growth and development of the follicle. Estrogen hormones formed in the follicle stimulate the tonic secretion of LH, FSH and LH cause the growth of the follicle to a preovulatory state. Estrogens secreted by the follicle, as well as a small amount of progesterone, stimulate the center that provides cyclic RF secretion, which causes an increase in LH secretion before ovulation.
After ovulation, the formed corpus luteum releases a significant amount of progesterone, while estrogen secretion decreases. At the same time, the secretion of LTG begins, which enhances the function of the corpus luteum. As a result, a significant amount of released progesterone suppresses the secretion of LH and, against the background of a decrease in the hormones of the pituitary gland and ovaries, menstruation occurs. The endometrium, having no hormonal activity, contributes to the involution of the corpus luteum.
However, the scheme of regulation of the menstrual cycle will remain incomplete, if we do not mention the role of other factors in its implementation. So, dysfunction of the adrenal glands and the thyroid gland can directly affect the processes of ovulation, up to its complete inhibition. The mediators of the autonomic nervous system act on the ovulatory process, and the sympathetic system inhibits the release of gonadotropic hormones, delaying ovulation, and the parasympathetic (acetylcholine) enhances the release of gonadotropins, stimulating it. Ovarian function is influenced by monoamines - adrenaline, norepinephrine, dopamine.
Cyclic fluctuations in the secretion of hormones cause corresponding changes in the ovary (ovarian cycle), uterus (uterine cycle), vagina (vaginal cycle), mammary gland, i.e. target organs for the action of sex hormones.
Ovarian cycle. The ovary performs two important functions, closely related to each other - generative (follicle maturation and egg release) and endocrine (cyclic secretion of steroid hormones).
There are two phases of the ovarian cycle - follicular, characterized by the development and maturation of the follicle and the release of steroid hormones (mainly estrogens), and luteal, characterized by the secretion of progesterone by the corpus luteum.
During the ovarian cycle, fluctuations in estrogen in the body occur: the curve of their excretion during the menstrual cycle has two maxima: the first - at the end of the folliculin phase, during ovulation, the second - in the heyday phase of the corpus luteum, approximately on the 19th-22nd day of the cycle. The first maximum usually exceeds the second.
The fractional composition of estrogens released during these two peaks is different: during the ovulatory period, the content of estradiol and estriol in the urine increases sharply, and in the luteal phase - estrone. Such fluctuations in the body of estrogens are observed throughout the childbearing period, stopping only during pregnancy and during breastfeeding.
As the menopause approaches, the estrogen saturation curve of a woman's body gradually decreases, and after the onset of menopause, it drops sharply. However, even during this period of life, as well as after bilateral oophorectomy, a small amount of estrogens continues to be determined, while estrogens are produced by the adrenal cortex.
During the luteal phase, progesterone is secreted, as well as estrogen, although in a smaller amount and in a different fractional composition than in the follicular phase of the cycle. The maximum progesterone secretion falls on the 21-24th day of the cycle - the phase of the heyday of the corpus luteum.
Under the influence of changes in the hormonal balance created by the ovarian cycles, uterine bleeding appears - menstruation, and changes occur in other target organs for the action of sex steroid hormones - the cervix, vagina, and mammary glands.
Uterine cycle. During the uterine cycle, the greatest changes occur in the functional layer of the endotherm. This layer is composed of mucus-secreting glands and epithelium, and is supplied with spiral arteries that change in parallel with changes in the endometrium.
According to the two phases of the ovarian cycle, two phases of endometrial development are distinguished - proliferation and secretion. If fertilization does not occur, then menstruation occurs.
The proliferative phase covers the period of time after the end of menstruation until ovulation. At the beginning of it, under the influence of estrogens produced by the follicle, the growth of the endometrium begins (the early folliculin phase continues until the 7-8th day of the cycle). The endometrial glands are short, elongated, lined with cylindrical epithelium. The stroma of the endometrium consists of spindle-shaped cells with a large nucleus, the spiral arteries are initially slightly tortuous, then grow rapidly and cover a significant part of the endometrium. The middle proliferative phase, which begins on the foyer of a continuing increase in estrogen secretion and lasts until the 10-12th day of the cycle, is characterized by elongated tortuous glands and increased growth of spiral arteries. Since the latter increase faster than the endometrium thickens, tortuous arteries appear. The spiral arteries have numerous arteriovenous anastomoses communicating with the venous sinuses that bleed during menstruation. Electron microscopic studies made it possible to establish signs of the secretory function of its glands already at this stage of endometrial development. The stroma of the endometrium becomes edematous, the number of mitoses increases in it.
The late proliferative phase, lasting until the 14-15th day of the cycle and ending with ovulation, is characterized by further elongation of the glands, expansion of their lumens, and an increase in the number of mitoses both in the cells of the glandular epithelium and in the stroma. The latter becomes juicy, with blood vessels concentrated around the glands of the endometrium. The onset of ovulation does not immediately affect the state of the endometrium, but after it comes the second phase - secretion.
The secretion phase covers the period after ovulation until menstruation. 2 days after ovulation, under the influence of estrogens and progesterone, the glands develop rapidly and their lumens expand, in which traces of secretion are determined. The spiral arteries become even more tortuous (early secretory phase, lasting until the 17-18th day of the cycle).
By the 18-20th day (middle secretory phase), two zones of the uterine mucosa are clearly visible: spongy, adjacent to the basal layer, thicker, containing more glands and a small amount of stroma, and superficial, much thinner, with fewer glands and a large number of connective tissue elements.
The endometrial glands acquire a sawtooth shape and secrete a mucous secret that fills most of the epithelial cells. The largest amount of secretion, consisting of acid mucopolysaccharides, glucoproteins and glycogen, is found by the 20-21st day of the cycle. By the same time, the activity of enzymes (fibrinolytic, proteolytic) in endometrial cells increases.
The spiral arteries at this time are sharply convoluted, the veins are dilated.
The late secretory phase, lasting until the 25th-27th day of the cycle, is initially characterized by maximum mucous secretion, well-developed glands, after which the growth of the endometrium stops, and then its regression begins.
By the end of this phase, coinciding with a decrease in the secretion of both estrogens and progesterone, there is an expansion of the vei of the endometrium, a decrease in its blood supply. The mucous membrane of the uterus becomes thinner, the spiral arteries are compressed and blood stasis is observed in them.
The secretion phase ends with menstruation, which is the desquamation of the entire functional layer of the endometrium, which is accompanied by more or less heavy bleeding. Before the onset of menstruation, there is a sharp narrowing of the spiral arteries.
Recently, there have been numerous reports on the importance of prostaglandins in the onset of menstruation. Czekanowski et al., Orcel et al. found very high levels of prostaglandins in the endometrium during menstruation as well as in menstrual blood. Hoarig-Ngoe Mink and co-authors proposed a new concept of the mechanism of menstruation, according to which the twisting of the spiral arteries and their compression before menstruation leads to a violation of the integrity of their terminal sections, resulting in contact of the endometrium with prostaglandins. Under the influence of the latter (mainly F2 and E2), the contractile ability of the uterus increases and histamine is released.
At the end of menstruation, after the rejection of the necrotic endometrium, the spiral arteries relax, blood circulation is improved in them, and the uterine mucosa regenerates.
In addition to the endometrium, the myometrium also changes during the menstrual cycle. So, in the luteal phase, under the action of progesterone, hyperplasia of the muscle fibers of the uterus occurs and its mass increases by 5-10 g. The contractile activity of the myometrium also changes: increasing towards ovulation, it sharply decreases in the luteal phase.
Neck cycle. When the level of sex hormones fluctuates, characteristic changes occur in the mucous membrane of the cervix. In the follicle and the new phase of the cycle, there is a growth of mucosal cells and a gradual increase in the secretion of mucin by the glands, the maximum secretion coincides with ovulation.
An increase in the content of estrogens in the body leads to an increase in cervical secretion: if on the 7-8th day of the menstrual cycle the cervical glands secrete 60-70 mg of mucus per day, then by ovulation - about 700 mg. In the luteal phase, mucus secretion again decreases to 50-60 mg per day.
In the cervical mucus, the content of water, phospholipids, mucopolysaccharides, as well as acidity change cyclically (with an increase in estrogens in the body for ovulation, the pH is 7.5-8, with a decrease in them, it changes to acidic - 6.5). Changing the properties of cervical mucus causes various options for its crystallization, which is often used for diagnostic purposes.
vaginal cycle. Cyclic changes in hormones in the body lead to vaginal cycles. In the folliculin phase, the vaginal epithelium grows, as ovulation approaches, the cells differentiate, by ovulation the epithelium reaches a maximum thickness of 150-300 microns, the entire thickness of the epithelium loosens, in the surface layer of which the maturation process begins. In the luteal phase, the growth of the epithelium stops and its desquamation begins, which is associated with the influence of progesterone.
During menstruation, the upper layers of the vaginal epithelium are torn off, which is easy to follow by examining vaginal smears taken in the dynamics of the menstrual cycle.
Breast cycle. In parallel with hormonal changes, more or less pronounced cyclic changes in the mammary gland occur.
In the follicular phase, the development of the tubular system and the expansion of the lobules of the gland occur, and in the luteal phase, a large number of small lobules are formed, surrounded by connective tissue, which leads to an increase in the volume of the gland and the appearance of a feeling of tension in it. Starting from the 1st day of menstruation, regressive changes occur in the mammary gland.
Physiology of the reproductive system. Levels of regulation.
Ovarian and menstrual cycles.
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.
The reproductive function of a woman is associated with pregnancy and childbirth. Pregnancy can occur only after the maturation of the reproductive system, which includes the ovaries and uterus, as well as the mechanisms of the neurohumoral-hormonal system that regulate their activity.
The reproductive or childbearing period is one of the longest in a woman's life. In connection with the state of the reproductive system, there are: prenatal period; neonatal period (up to 1 year); childhood (up to 7-8 years); puberty - prepubertal (up to 14 years old) and pubertal (up to 17 years old); childbearing, or reproductive (up to 40-45 years). Then comes the last menstruation - menopause (menos - month, pauses-end), and then follows postmenopause, associated with the gradual withering of the body. 2-3 years before menopause (premenopause) and 2 years after it (early postmenopause) is called the period of perimenopause. Perimenopause is a transitional period, which was previously called menopause. At this time, the function of the ovaries gradually fades away, an imbalance of hormones involved in the regulation of reproductive function is observed.
The allocation of these periods of a woman's life is to a certain extent conditional, since individual fluctuations are extremely large. Nationality, living conditions, climate features are of great importance. So, in the southern regions, prepubertal and pubertal periods, as well as menopause in women, occur earlier.
In physiology, the principle of homeostasis, formulated by Claude Bernard, is generally accepted. According to this principle, any of the indicators of metabolism must be within certain and narrow enough limits to remain compatible with life. Examples are the constants of the acid-base state of the body and the gas composition of the blood, the function of the endocrine glands and glucose metabolism, etc.
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.
In the regulation of the reproductive system, five levels are distinguished, which act on the principle of direct and feedback due to the presence of receptors for sex and gonadotropic hormones in all links of the chain.
First (highest) level regulation of the reproductive system are the cerebral cortex, hypothalamus and extrahypothalamic cerebral structures, limbic system, hippocampus, amygdala.
The role of the CNS in the regulation of the menstrual cycle was known before the release of hormones and neurosecretion. We observed the cessation of menstruation during stress, with a very strong desire to have a pregnancy, or with a fear of becoming pregnant in women with an unstable psyche. Currently, specific receptors for sex hormones have been identified in the cerebral cortex, hypothalamus, and extrahypothalamic structures. In addition, in response to external and internal stimuli in the cortex and subcortical structures, the synthesis and release of neurotransmitters and neuropeptides occur, which primarily affect the hypothalamus, promoting the synthesis and release of releasing hormone.
The cerebral cortex secretes endogenous opioid peptides (EOP): enkephalins, endorphins and dynorphins. These substances are found not only in various structures of the brain and the autonomic nervous system, but also in the liver, lungs, pancreas and other organs, as well as in some biological fluids (blood plasma, follicle contents). According to modern concepts, image intensifier tubes have an effect on the hypothalamus.
To the most important neurotransmitters, those. Transmitters include norepinephrine, dopamine, gamma-aminobutyric acid (GABA), acetylcholine, serotonin, and melatonin.
Cerebral neurotransmitters regulate the production of gonadotropin-releasing hormone (GnRH); norepinephrine, acetylcholine and GABA stimulate their release, while dopamine and serotonin have the opposite effect.
Neuropeptides(endogenous opioid peptides, corticotropin-releasing factor and galanin) also affect the function of the hypothalamus and the balance of the functioning of all parts of the reproductive system.
Second level regulation of the reproductive system is the hypothalamus, which secretes stimulating (liberins) and blocking (statins) neurohormones. Cells that secrete neurohormones have the properties of both neurons and endocrine glands.
The hypothalamus secretes GnRH containing follicle-stimulating (FSH - folliberin) and luteinizing (RGLH - luliberin) hormones that act on the pituitary gland.
The releasing hormone LH (RGLG - luliberin) has been isolated, synthesized and described in detail. To date, it has not been possible to isolate and synthesize releasing-follicle-stimulating hormone.
GnRH secretion is genetically programmed and has a pulsatile (circhoral) character: peaks of increased hormone secretion lasting several minutes are replaced by 1-3-hour intervals of relatively low secretory activity. The frequency and amplitude of GnRH secretion in the preovulatory period against the background of maximum estradiol release is significantly higher than in the early follicular and luteal phases.
The activity of the hypothalamus is closely related to the function of the pituitary gland.
To the third level regulation includes the anterior lobe of the pituitary gland (adenohypophysis), in which the follicle-stimulating hormone, or follitropin (FSH), is synthesized; luteinizing, or lutropin (LH); prolactin (PrL); adrenocorticotropic (ACTH); somatotropic (STG); thyrotropic or thyroliberin (TSH); FSH, LH, PrL act on the ovary. PrL stimulates the growth of the mammary glands and lactation, controls the secretion of progesterone by the corpus luteum by activating the formation of LH receptors in them.
The synthesis of PrL by the adenohypophysis is under the tonic blocking control of dopamine, or the prolactin inhibitory factor. Inhibition of PrL synthesis stops during pregnancy and lactation. The main stimulator of PrL synthesis is TSH synthesized in the hypothalamus.
The remaining hormones of the pituitary gland affect the endocrine glands corresponding to their name. Only with a balanced release of each of the pituitary hormones is the normal function of the reproductive system possible.
To the fourth level regulation of reproductive function include peripheral endocrine organs (ovaries, adrenal glands, thyroid gland). The main role belongs to the ovaries, and other glands perform their own specific functions, while maintaining the normal functioning of the reproductive system.
Fifth level regulation of reproductive function are sensitive to fluctuations in the levels of sex steroids internal and external parts of the reproductive system (uterus, fallopian tubes, vaginal mucosa), as well as the mammary glands. The most pronounced cyclic changes occur in the endometrium.
The cyclicity of the system that regulates the reproductive function is determined by direct and feedback between the individual links. So, FSH, thanks to receptors in the follicular cells of the ovary, stimulates the production of estrogens (direct connection). Estrogens, accumulating in large quantities, block the production of FSH (feedback).
In the interaction of the links of the reproductive system, “long”, “short” and “ultra-short” loops are distinguished. "Long" loop - impact through the receptors of the hypothalamic-pituitary system on the production of sex hormones. The "short" loop determines the connection between the pituitary gland and the hypothalamus, the "ultrashort" loop determines the connection between the hypothalamus and nerve cells, which carry out local regulation with the help of neurotransmitters, neuropeptides, neuromodulators and electrical stimuli.
This system, which regulates the reproductive function of the body, determines two-phase changes in the ovaries, uterus and throughout the body of a woman.
A reflection of the maturity of the reproductive system is the establishment of the menstrual cycle.
MENSTRUAL CYCLE
The menstrual cycle implies cyclical changes throughout the woman's body, mainly in the reproductive system, the external manifestation of which is blood discharge from the genitals - menstruation. During the menstrual cycle in the ovaries, the maturation of the egg occurs, and in the case of fertilization, the implantation of the embryo into the prepared uterine mucosa.
Menstruation - bloody discharge from the genital tract, repeated at a certain interval during the reproductive period. Normally, menstruation is absent during pregnancy and lactation.
The first menstruation (menarche) occurs at 10-12 years before the maturation of the egg, or it may be the result of its maturation. Therefore, sexual intercourse that occurred before the first menstruation can lead to pregnancy. After menarche, menstruation either immediately becomes regular, or within 1-1.5 years they occur after 2-3 months and only after this time do they become regular.
The appearance of menstruation does not yet indicate the readiness of the body to carry a pregnancy. If pregnancy occurs before the age of 17, then pregnant women are classified as "young" primiparous. It is believed that “young primiparas” are neither physically nor psychologically ready for the birth and upbringing of a child. The female body is completely ready for childbirth at the age of 17-18 years.
Most obstetricians take the 1st day of menstruation as the 1st day of the menstrual cycle.
The duration of the menstrual cycle in 60% of women is 28 days. This value is taken as the main one, in relation to it it is customary to calculate the duration of the individual phases of the cycle. However, this value can normally fluctuate 28 ± 7 days (from 21 to 35 days). The duration of menstruation is 3-7 days, blood loss is 40-60 ml.
The maturation of the egg in the ovary and the secretory transformations of the endometrium reflect cyclic changes in the woman's body - the menstrual cycle, and they predetermine the possibility of pregnancy.
The menstrual cycle has two distinct phases; 1st phase - follicular, 2nd - luteal. In the 1st phase, the follicle grows (folliculogenesis) and the maturation of the egg, which leads to ovulation - a violation of the integrity of the follicle and the entry of the egg into the abdominal cavity, in the 2nd, luteal, phase, a corpus luteum forms at the site of the ruptured follicle.
At birth, a girl's ovaries contain approximately 2 million primordial follicles. Their bulk undergoes atretic changes throughout life, and only a very small part goes through a full development cycle from primordial to mature with the subsequent formation of the corpus luteum. By the time of menarche, the ovaries contain 200-400 thousand primordial follicles. During one menstrual cycle, as a rule, only one follicle with an egg develops. The maturation of more follicles contributes to multiple pregnancy.
In folliculogenesis, the formation of a primordial follicle, preantral, antral, dominant is distinguished.
Primordial follicle is an immature egg surrounded by follicular and granular (granular) epithelium. Outside the follicle there are connecting theca cells of an elongated shape. During the menstrual cycle, 3 to 30 primordial follicles transform into preantral follicles.
preantral or primary follicle more primordial due to proliferation of the granulosa layer. The ovum is slightly enlarged and surrounded by a shiny membrane - zone pellicida.
granulosa cells antral, or secondary, follicle increase and produce follicular fluid, which, accumulating, forms the cavity of the egg.
Dominant (preovulatory) follicle released by day 8 cycle from antral follicles. It is the largest, up to 20 mm in diameter. The dominant follicle has a richly vascularized layer of granulosa cells and theca cells. Along with the growth of the dominant follicle, the egg (oocyte) matures, in which meiosis occurs. The formation of a dominant follicle is accompanied by reverse development, or atresia, of the remaining (recruited) follicles that have entered into development.
Ovulation- rupture of the mature dominant follicle and exit from it into the abdominal cavity of the egg. Ovulation is accompanied by bleeding from broken capillaries. After the release of the egg, the resulting capillaries quickly grow into the cavity of the follicle. Granulosa cells undergo luteinization: the volume of the cytoplasm increases in them and lipid inclusions appear - a corpus luteum is formed.
corpus luteum- transient hormonally active formation, which, regardless of the duration of the menstrual cycle, functions for 14 days. If pregnancy does not occur, then the corpus luteum regresses, but if fertilization occurs, then it progresses and reaches its climax.
The growth, maturation of the follicle and the formation of the corpus luteum are accompanied by the production of sex hormones by both the granulosa cells of the follicle and theca cells.
The ovarian sex steroid hormones include estrogens, progesterone, and androgens. 90% of these hormones are in a bound state, the remaining 10% have a biological effect.
Estrogens are divided into three fractions of different activity: estradiol, estriol, estrone. The most active is estradiol, the least is estrone. The amount of sex hormones changes throughout the menstrual cycle, which is determined by the activity of granulosa cells. As the follicle grows, the synthesis of all sex hormones increases, but mainly estrogens. In the period from ovulation to the onset of menstruation, progesterone, secreted by the cells of the corpus luteum, joins estrogen. Androgens are secreted in the ovary by interstitial cells and theca cells, their level does not change during the menstrual cycle.
Thus, in the phase of maturation of the follicle, estrogens are predominantly secreted, in the phase of the formation of the corpus luteum - progesterone. Sex hormones synthesized by the ovaries affect target tissues and organs containing receptors for them: these are the genital organs (uterus, mammary glands), spongy bone, brain, endothelium and vascular smooth muscle cells, myocardium, skin and its appendages ( hair follicles and sebaceous glands), etc.
In the skin, under the influence of estradiol and testosterone, collagen synthesis is activated, which helps to maintain its elasticity. Increased sebum, acne, folliculitis, porosity, and excess hair are associated with increased exposure to androgens.
In bones, estrogens, progesterone, and androgens support normal remodeling by preventing bone resorption.
The balance of estrogens and androgens determines both the activity of metabolism and the distribution of adipose tissue in the body.
Sex steroids (progesterone) significantly modulate the work of the hypothalamic center of thermoregulation.
With receptors for sex steroids in the central nervous system, in the structures of the hippocampus that regulate the emotional sphere, as well as in the centers that control autonomic functions, the phenomenon of the "menstrual wave" in the days preceding menstruation is associated. This phenomenon is manifested by an imbalance in the processes of activation and inhibition in the cerebral cortex, fluctuations in the tone of the sympathetic and parasympathetic systems (especially noticeably affecting the functioning of the cardiovascular system), and externally manifests itself as a change in mood and some irritability. In healthy women, these changes, however, do not go beyond the physiological boundaries.
In addition to steroid hormones, the ovaries also secrete other biologically active compounds: prostaglandins, oxytocin, vasopressin, relaxin, epidermal growth factor (EGF), insulin-like growth factors (IPFR-1 and IPFR-2).
It is believed that growth factors contribute to the proliferation of granulosa cells, the growth and maturation of the follicle, and the selection of the dominant follicle.
In the process of ovulation, prostaglandins F 2 α and E 2 play a certain role, as well as proteolytic enzymes contained in the follicular fluid, collagenase, oxytocin, relaxin. Ovulation is closely related to the increase (peak) of estrogen.
Cyclic secretion of sex hormones (estrogens, progesterone) leads to two-phase changes in the endometrium, aimed at the perception of a fertilized fetal egg.
CYCLIC CHANGES IN THE UTERINE MUCOSA (ENDOMETRIUM). PREPARATION FOR PREGNANCY
The mucous membrane of the uterus during menstruation is rejected and subsequently, under the influence of estrogens, passes the phase proliferation and under the predominant influence of progesterone - the phase secretions. After rejection of the functional layer of the endometrium during menstruation, the body of the uterus is covered from the inside with a thin basal layer (1-2 mm). The glands are narrow, straight, short, lined with low cylindrical epithelium. The cells of the functional layer are formed from the cells of the basal layer. These changes are carried out both in the glands and in the stroma of the functional layer of the endometrium. In the phase of proliferation under the influence of estrogens, the height of epithelial cells increases, the epithelium from a single-row epithelium at the beginning of proliferation turns into a multi-row one by the time of ovulation. The glands elongate and become tortuous. The number of mitoses increases. The stroma of the mucous membrane becomes edematous and loosens, the cell nuclei and the volume of the cytoplasm increase in it. The thickness of the endometrium reaches 8 mm. The endometrium is able not only to perceive the influence of estrogens, but also to synthesize them by converting androstenedione and testosterone with the participation of aromatase. Such a local pathway for the formation of estrogens enhances their effect on the proliferative process.
In phase secretions the number of estrogen receptors in the endometrium is reduced and the proliferation of endometrial cells is inhibited. Under the influence of progesterone, glycogen-containing vacuoles appear in the cells of the endometrium, and a secret appears in the glands, which contains glycogen, glycoproteins, glycosaminoglycans. In the secretion phase, two layers of cells are defined in the functional layer: superficial, more compact, and spongy, having a spongy structure.
On the 6-7th day after ovulation (20-21st day of the menstrual cycle) there are the best conditions for the implantation of a fertilized egg. From the 21st day of the menstrual cycle, a decidual reaction of the endometrial stroma is observed, resembling that of pregnancy. By the 26th day, the decidual reaction (accumulation of cells rich in glycogen) becomes maximum. These cells are believed to play a major role in trophoblast invasion. The spiral arteries during this period of the menstrual cycle are significantly tortuous. Approximately 2 days before menstruation, an accumulation of neutrophils migrating from the bloodstream occurs in the stroma of the endometrium.
If fertilization does not occur, involution of the corpus luteum occurs. The blood levels of both estrogen and progesterone fall, which promotes menstruation.
Menstruation, Under the influence of a decrease in the content of sex hormones in the blood, spasm of the spiral arteries, ischemia and necrosis of the endometrium occur. As a result of insufficient blood supply to the endometrium, lysosomal proteases are released, vasodilation occurs again, which leads to rejection of the necrotic tissue of the functional layer with a violation of the integrity of the vessel walls - menstruation.
Prostaglandins play an important role in the onset of menstruation. Prostaglandin F 2 α has a vasoconstrictive effect on the spiral arteries, leading to endometrial ischemia. In addition, prostaglandin F 2 α contributes to the reduction of the myometrium, and therefore, the removal of the rejected uterine mucosa. An increase in the release of prostaglandins during menstruation is associated with the release of certain enzymes by lysosomes.
From the very beginning of menstruation, the regeneration of the cellular composition of the endometrium from basal cells occurs, which is completed by the 4-5th day of the menstrual cycle. In parallel, the integrity of the destroyed arterioles, veins, capillaries is restored.
The endometrium is able to synthesize not only estrogen, but prolactin.
In a healthy woman, during the reproductive period, all cycles are ovulatory, and in total 350-400 eggs mature.
The generative function is a manifestation of the ovulatory process and should be maintained from 15 to 45 years. The formation and extinction of the reproductive system occurs according to the same mechanisms, but in reverse order. Initially, during puberty, secondary sexual characteristics appear as a manifestation of steroidogenesis in the ovaries. Then menstruation appears, while at first the menstrual cycle is anovulatory, then ovulatory cycles with luteal phase deficiency appear, and, finally, a mature, reproductive type of functioning of the entire system is established. When the reproductive system is turned off, depending on age or on various stress agents, ovulatory cycles first appear with hypofunction of the corpus luteum, then anovulation develops, and with severe inhibition of the reproductive system, amenorrhea occurs.
In a population of healthy women with a regular menstrual cycle lasting 26-30 days, the number of anovulatory cycles is minimal and is about 2.0%. In a population of women with variable menstrual cycles (from 23 to 35 days), the number of cycles with luteal phase deficiency (LFP) increases, and the number of anovulatory cycles increases to 7.7%. The lability of the menstrual cycle is associated primarily with the woman's age and is most pronounced in the first years after menarche and in the last years before menopause. With age, the duration of the menstrual cycle tends to shorten.
The concept of "norm" is such a state of the reproductive system, which implies the potential for the implementation of the generative function. The definition of "fertile cycle" should include the presence of normal hormonal blood parameters necessary for the functioning of the entire reproductive system. Violations in the secretion of hormones of the menstrual cycle are detected with gross breakdowns in the reproductive system. There is no absolute direct correlation between endocrine and reproductive functions proper.
All processes associated with procreation: maturation of sperm and eggs, ovulation, preparation of the uterus to receive the embryo, maintenance of pregnancy and childbirth, are subject to strict control. How is it carried out?
Signals from the external and internal environment enter the brain, in hypothalamus- the highest center of regulation of the organs of blood circulation, respiration, digestion, excretion and reproduction. In the hypothalamus, the information received is processed and, depending on the result of the analysis, a command follows to the nearby endocrine gland - pituitary, which is the immediate "chief" of all endocrine glands in the body (adrenal, thyroid, parathyroid, thymus and gonads). The hypothalamus transmits its commands to the pituitary gland with the help of special hormones, which, depending on the direction of their action, are called hormone releasing(from English release - "release") or inhibitory hormones(from lat. inhibeo - "restrain, stop").
To regulate the function of the sex glands in the pituitary gland, 3 hormones are produced, which are called gonadotropins(Greek tropos - "direction"). This: luteinizing hormone(abbreviated LG), follicle stimulating hormone (FSH)) And prolactin. Moreover, FSH and LH are produced under the stimulating effect of gonadotropin-releasing hormone (GnRH), and the release of prolactin is determined by an increase or decrease in the concentration of the inhibitory factor. Despite the fact that these hormones are the same in structure in men and women, they work differently in the two sexes.
Regulation of reproductive function in men
FSH in men it is necessary for the normal formation, development and function of the seminiferous tubules. FSH actively affects spermatogenesis. LG Stimulates the production of androgens, the male sex hormones, by the testicles. Prolactin in men potentiates the action FSH And LG, affects the metabolic processes in the testicles.
The most important of the androgens is the hormone testosterone. Without this hormone, normal spermatogenesis. In addition, testosterone is responsible for the normal formation of male genital organs, the appearance of secondary male characteristics (hair growth, a characteristic male physique), and also affects sexual behavior.
Secretion testosterone carried out according to the principle of direct and feedback: the hypothalamus stimulates the production of gonadotropins by the pituitary gland, under the influence of gonadotropins, the secretion of testosterone by the testicles increases - this is an example of a direct positive relationship. When the upper limit of testosterone concentration in the blood is reached, the so-called negative feedback begins to act, i.e. testosterone begins to inhibit the secretory activity of the hypothalamus and pituitary gland. When the concentration of testosterone in the blood falls to the lower limit, the hypothalamus again stimulates the production of testosterone through the pituitary gland. Thanks to such connections, the hypothalamus controls and regulates all processes occurring in the genital area.
Regulation of reproductive function in women
Hormonal regulation in the female body is more complicated than in the male. In a woman’s body, unlike a man’s, cyclical changes occur monthly, which are combined into one concept - menstrual cycle. These changes affect both the ovaries, in which eggs mature, and uterus, in which conditions are created for the onset of pregnancy, and cervix, the fallopian tubes And mammary gland, and even the skin and subcutaneous fat, in general, all the so-called "target organs".
The duration of the menstrual cycle normally ranges from 21 to 32-34 days. Its beginning (day 1) is considered to be the beginning of bleeding ( menses), which is caused by rejection of the mucous layer of the uterus ( endometrium). The duration of menstruation (monthly) is 3-4 days. A normal menstrual cycle should be regular.
Already during menstruation, the level of follicle-stimulating hormone begins to rise. FSH stimulates the growth of several follicles at once. However, as a rule, only one follicle reaches full maturity - the dominant follicle. Before ovulation, its diameter increases to 18-23 mm. The rest, which began to grow follicles, degenerate, that is, they undergo reverse development. From the first days of the menstrual cycle, production by the pituitary gland gradually increases. LG. In the middle of the menstrual cycle, there is a short release - the peak of the secretion of this hormone into the blood. Influenced by peak LG over the next 34-36 hours, the final maturation of the egg occurs, which ends with the rupture of the follicle and the release of the egg into the abdominal cavity, that is, ovulation. By level LG in the blood or urine of a woman, the time of ovulation can be fairly accurately predicted. After ovulation, under the influence of gonadotropins, the corpus luteum is formed from the follicle.
Prolactin support function corpus luteum and is responsible for the secretion of milk in the mammary glands. With an increase in its concentration in the ovaries, the development of follicles is inhibited, it may stop ovulation.
FSH And LG control the secretion of sex hormones in the ovary. The cells of the growing follicle produce hormones called estrogen(from the Greek oistrus - estrus, a state of sexual arousal in animals + genes - birth, origin), the main of which are estradiol, estriol and estrone. Estrogens determine the female image, affect the development of secondary sexual characteristics. Under their influence, the mammary glands develop, hair grows according to the female type, a female physique and voice timbre are formed.
In a woman of reproductive age, estrogens monthly prepare the body for a possible pregnancy. During menstruation endometrium- The mucosa lining the uterine cavity becomes thinner sharply. Under the influence of ever-increasing production of estrogen by the ovary, the endometrium begins to proliferate, i.e. grow, thicken, glands appear in it, vessels develop. At the same time, estrogens cause changes in fallopian tubes. The fallopian tubes and the cilia of the epithelium of the inner layer of the tubes begin to move in a certain way, contributing to the current of the secret in them from the uterus to the ampullar section of the fallopian tube, thereby contributing to the advancement of spermatozoa in the lumen of the tube. Estrogens reduce muscle tone cervix, resulting in an increase in the diameter of the cervical canal. His external pharynx begins to gape. Under the influence of estrogens, the mucus in the lumen of the canal liquefies and hangs down into the vagina with long threads. These changes are most pronounced before ovulation, when estrogen levels are at their highest. Thus, by the time of ovulation, the most favorable conditions are created for spermatozoa on the way to the cherished egg.
The main hormone of the corpus luteum is progesterone. It is also known as the pregnancy hormone. The duration of the existence of the corpus luteum will depend on whether pregnancy has occurred or not. Under the influence of progesterone, the endometrial glands begin to actively produce and accumulate a secret containing the nutrients necessary for the development of the ovum and embryo. After ovulation, under the influence of progesterone, the direction of contractions of the muscles of the fallopian tubes and the wave-like movements of the ciliated epithelium changes to the opposite direction, namely, to the uterus. This ensures the transport of the embryo into the uterine cavity.
If fertilization does not occur, then corpus luteum, having existed for about 2 weeks, degenerates, and the secretion of progesterone is reduced to a minimum. 2-3 days after the fall in the level of ovarian hormones, endometrial rejection occurs, i.e. menstruation, and a new menstrual cycle begins.
If pregnancy occurs, the corpus luteum continues to function, they say - it "blooms". This happens because the fetal egg releases a special hormone into the mother's blood, called chorionic(from the Greek. chorion - the outer shell of the fetal egg) gonadotropin, which stimulates the functional activity of the corpus luteum. So, the embryo itself affects the mother's body, stimulates processes in it that ensure the preservation and development of pregnancy.
From the above it is easy and correct to conclude that ovary is a powerful hormonal laboratory. Of course, the subtle mechanism of regulation of reproductive processes can be disturbed, and then ovarian failure develops. It can manifest itself in weakness, insufficient hormonal activity of the follicles or the corpus luteum, which leads to menstrual irregularities, infertility. In some diseases, for example, with polycystic disease, the ovarian laboratory begins to produce male hormones, which is manifested not only by a violation of the menstrual cycle, but also by the appearance in a woman of some features characteristic of men, for example: facial hair growth, coarsening of the voice, etc.