Obstetrics and Gynecology - A.M. Hromova 2000

Anatomical and Physiological Characteristics of the Female Body
Physiological Characteristics of the Female Body

The Functions of the FEMALE REPRODUCTIVE Organs are closely linked to The activity of the entire Organism and the external environment. The overall condition of the body, the state of the Central Nervous system (CNS), and previous infectious diseases strongly influence the development and normal functioning of the female genital organs. It is particularly important to account for infections contracted during childhood, during the formation and Development of the FEMALE Reproductive System.

A proper understanding of the PHYSIOLOGY OF THE reproductive organs is gained by studying the biological processes taking place in the body of an adult woman with a normal Menstrual cycle, where all functions of the organism as a whole are harmoniously interrelated.

Based on the biological CHARACTERISTICS OF THE female body, the following periods of a woman's life are distinguished: embryonic, childhood, Puberty, reproductive maturity, transitional (Climacteric), postclimacteric (menopause), and senile (senium).

The Embryonic period spans from the moment of conception to the full maturation of the fetus and its birth. A crucial feature of ovarian development in ontogenesis is the bisexuality of its primordium. The rudiment acquires sex-specific traits as the sex center of The Nervous System differentiates. Once acquired, the sexual identity remains stable and does not disappear either after castration or during the climacteric period. From the end of the eighth week of embryonic development, primary follicles appear in the Ovary; after some time, they transform into vesicular ovarian follicles and begin to function.

Early childhood lasts from birth up to 10–11 years of age. In the first years of a girl's life, the cortical layer of each ovary contains up to 200,000 primordial follicles (i.e., a total of about 400,000). During this period, a follicle consists of an ovum surrounded by a single-layered sheath of follicular Cells and an outer layer. Follicles located close to the ovarian surface are considered underdeveloped. Deeper layers contain more mature follicles, in which the epithelium surrounds the ovum in 2–3 layers, follicular fluid begins to appear, and the theca interna is formed.

Throughout the first 10 years of a girl's life, the GROWTH AND DEVELOPMENT of the follicle proceed very slowly. Prior to the onset of the first menstruation, the follicle never reaches full maturity, and ovulation does not occur.

The hormonal function of the prepubertal ovary is very low. Small amounts of estrogens and androgens are detected in the bodies of girls of this age. It should be noted that boys of the same age secrete approximately similar amounts of androgens.

Starting from the age of ten, the number of maturing follicles in the ovary increases, and consequently, the level of estrogens in the body rises. Their level increases sharply from the age of 12 (compared to the age of 10, The amount of estrogens increases by 10–15 times, being 60% higher than in sexually mature women).

One to 1.5 years before the onset of menstruation, estrogen production becomes cyclical. At this time, it is difficult to distinguish girls from boys, but later significant differences appear: the girl's pelvis is wider, the chest is narrower, and the facial features are more delicate. General development occurs earlier in girls than in boys.

In a newborn girl, the vaginal epithelium is delicate, low, and single-layered; later it will consist of several Cell layers, while in a sexually mature woman it is multi-layered, with surface keratinization even occurring. In childhood, the uterine body is smaller than the uterine cervix, whereas in an adult woman it is the other way around. Sometimes in the first days after birth, girls experience short-term and minor bloody vaginal discharge, as well as breast engorgement. This can be explained by the fact that small amounts of maternal estrogens cross the placental barrier to the fetus during intrauterine life.

The fallopian tubes are relatively long, thin, and tortuous. The Vagina and its fornices are short, narrow, and rugose; the mucosal folds are well-defined but easily smoothed out, lacking the elasticity found in adults. The vagina is positioned almost vertically in the lesser pelvis and only with age forms an acute angle with the horizontal plane of the pelvic outlet. The mucosal epithelium contains insufficient Glycogen, and the vaginal fluid reaction is weakly alkaline, which predisposes to The Development of vaginitis.

The period of puberty (pubertal period) ranges from 10–11 to 16 years of age.

From the age of 10, the lumen of the tubes increases, they become thicker, the uterine mucosa begins to develop, and the vagina lengthens. In conjunction with the growth of the entire body, the reproductive organs also develop. The girl's overall appearance changes as well. At this time, the secretory function of the Ovaries begins with The production of estrogens. The body acquires rounded contours due to subcutaneous fat deposition (on the thighs and lower abdomen), pubic Hair grows in a female pattern (in the shape of a triangle), and the Mammary Glands enlarge and develop. The first menstruation appears, indicating undulating Changes in the ovary characterized by follicle maturation and the onset of ovulations. Cyclic changes in the ovary and Uterus proceed regularly right up until the climacteric. Simultaneously, undulating changes occur throughout the entire organism (METABOLISM, CNS function).

In Ukraine, the first menstruation in girls normally appears at 12–14 years of age. Mensis occurring before 10 years and after 16 years is considered a consequence of certain body dysfunctions—such as insufficient general metabolism or developmental disorders—or the result of pathological processes in various organs (most often in the Endocrine glands). The onset time of the first menstruation depends on climatic conditions: earlier in southern regions and later in northern ones. Girls with an asthenic body type menstruate earlier, while those with a pyknic build menstruate later. A rare case of early mensis at 3 years of age has been described; this girl gave birth to a child at age 10. Heller in 1776 described childbirth in a 9-year-old girl who menstruated until the age of 52. Khazhynsky and Yershov described childbirth in a 6.5-year-old girl.

During puberty, sexual differentiation is finally completed, and a normal biphasic menstrual cycle is established.

Prior to menstruation, a woman may experience irritability, edginess, drowsiness, rapid fatigue, and excessive sweating. This is because the cyclic changes in the ovary and uterus are perceived by the nerve endings of the reproductive system, transmitted to the CNS, and affect its function. During a normal menstrual cycle, changes in the CNS remain within physiological limits and do not impair overall working capacity. Changes also occur in metabolism, thermoregulation, and Blood Circulation; the pulse becomes more frequent, body Temperature is slightly elevated, whereas arterial pressure during mensis, conversely, drops. Before mensis, the count of leukocytes, erythrocytes, and Hemoglobin increases, and then decreases with the onset of mensis, but rapidly returns to normal values. During mensis, The Thyroid Gland and Adrenal Glands enlarge slightly. Special changes take place in the Hypothalamus and Pituitary gland, which will be described in more detail below. By the end of this period, all female organs and systems achieve functional maturity and become capable of reproductive function.

The period of reproductive maturity begins at age 16 and continues until 43–48 years of age. During this period, all specific functions of the female organism aimed at childbearing reach their maximum activity. Its most characteristic feature is the presence of a biphasic menstrual cycle and a regular menstrual rhythm.

The transitional (climacteric) period occurs at the age of 48–55 years and lasts for 3–5 years. During this period, follicular maturation and the endocrine function of the ovaries gradually fade.

The climacteric period comprises two stages:

- climacteric changes;

- menopause.

The stage of climacteric changes lasts from 2 to 3 years. The Main Features of ovarian function are a gradual transition to a monophasic cycle and menstrual irregularities. Subsequently, menstrual function ceases, and the Second Stage—menopause—begins. Menopause on average lasts from 2 to 5 years after the cessation of menstrual function.

The climacteric period is characterized by the involution of the female reproductive system with the gradual cessation of the menstrual and, subsequently, hormone-producing functions of the ovaries. The climacteric ensues As a result of Aging of the hypothalamus and disruption of the rhythmic synthesis and release of releasing factors, primarily LH. This leads to impaired follicular maturation and steroidogenesis in the ovaries. The production of estrogens and progesterone sharply decreases, feedback mechanisms with the hypothalamus are disturbed, and stimulation of FSH, LH, and LTH (prolactin) production in the Pituitary Gland ceases. The reproductive organs undergo atrophic changes.

The ovary decreases in size (its peak weight at 30–40 years is 9 g, and at 60–70 years it is 4 g), undergoing regressive changes. Abundant Connective Tissue appears in the ovary, Blood Vessels undergo sclerosis, and the ovary gradually shrinks.

In the uterus, mucosal atrophy occurs, the myometrium diminishes, and obliteration in the area of the isthmus may occur. The weight of the uterus at 30–50 years is 70 g, and at 60–70 years it is 35 g.

The vaginal epithelium loses its elasticity, and the connective tissue becomes wrinkled.

In most cases, the menopausal period proceeds physiologically without drastic changes in the body; however, acyclic uterine bleeding and angioneurosis may sometimes occur as a result of endocrine, nervous, and Vascular System dysfunctions. Angioneurosis manifests as increased irritability, dizziness, hot flashes, sudden sensations of heat, and fluctuations in blood pressure, among other symptoms.

The postmenopausal period (menopause) spans from 49–50 to 57–59 years of age. General and local changes occur in the body. General changes include a predisposition to obesity, wrinkling, and a decreased sex drive, while local changes involve the gradual Atrophy of the uterus and mammary glands, and the cessation of menstruation. Atrophy of the reproductive organs occurs significantly later than the cessation of menstruation.

The senile period is The final stage of a woman's life, lasting from 59–60 years until the end of life. It is characterized by age-related changes throughout the entire body, a decrease in working capacity, the physiological quiescence of the reproductive system, and age-related hypoplasia of the reproductive organs.