Secondary sexual characteristics are signs that characterize changes in the structure and function of various organs that determine both sexual maturity and gender. Should be distinguished from primary sexual characteristics, which identify the genitals. Secondary sexual characteristics depend on the primary ones, develop under the influence of sex hormones and appear during puberty. These include features of the development of the musculoskeletal system, body proportions, subcutaneous fat and hair, the degree of development of the mammary glands, timbre of voice, behavioral characteristics and many others.

Under the influence of female sex hormones, girls quickly increase in height and body weight, and the limbs grow faster than the body; the shape of the skeleton, especially the pelvis, changes, as well as the figure due to the deposition of fat, mainly in the buttocks, abdomen and thighs; body shapes are rounded, the skin becomes thinner and more delicate. The growth of the mammary glands begins, the areola protrudes. Subsequently, the mammary glands enlarge, fatty tissue is deposited in them, and they take on the shape of a mature mammary gland. Hair appears on the pubis, then in the armpits, and its growth on the head increases. The growth of pubic hair in girls begins earlier than in boys, and is characterized by a distribution in the form of a triangle, characteristic of women, with the apex directed downwards and a sharply defined upper border above the pubis. Sweat glands, especially the glands of the armpits, begin to secrete sweat with an odor characteristic of the female sex. The secretion of the sebaceous glands increases, resulting in the formation of juvenile acne in the second half of puberty. For most girls, 2 - 3 years after the onset of secondary sexual characteristics, at the age of 12 - 13 years, menstruation begins (see Menarche) - the main sign of puberty, indicating the body's ability to become pregnant. However, the general maturity of the body occurs after several years, during which further development of secondary sexual characteristics and the formation of reproductive function occur, preparing the girl’s body to perform the function of motherhood.

In boys, the appearance of secondary sexual characteristics is characterized by more intense body growth, increased muscle mass, increased growth of the penis and testicles (which is sometimes accompanied by slight pain). The shape of the larynx changes, the voice becomes rougher and lower, pigmentation of the skin of the scrotum appears, hair appears on the pubis and in the armpits, a mustache and beard begin to emerge, and an Adam’s apple (“Adam’s apple”) appears. During this period, many young men experience swelling of the mammary glands and increased sensitivity of the nipples. At the age of 14 - 15, young men often experience sexual arousal, and at night - spontaneous ejaculation of semen (emission). The seminiferous tubules of immature boys are filled with spermatogonia, and only with the beginning of the functioning of the sex glands capable of producing mature sperm, the young man’s body enters the time of puberty, further developing secondary sexual characteristics and maturity, which occurs by 23 - 25 years.

Primary and secondary sexual characteristics

Sex characteristics are divided into two groups: primary and secondary.

Primary sexual characteristics are represented by organs directly involved in the processes of reproduction, i.e., in gametogenesis and fertilization. These are the external and internal genitalia. They are laid down during embryogenesis and by the time the organism is born, they are already more or less formed.

Secondary sexual characteristics do not take a direct part in reproduction, but contribute to the attraction of individuals of the opposite sex. They depend on primary sexual characteristics, develop under the influence of sex hormones and appear in organisms during puberty (in humans at 12-15 years of age). Such signs include features of the development of the musculoskeletal system, the degree of development of subcutaneous fatty tissue and hair, timbre of voice and characteristics of human behavior, special scent glands in animals, singing and plumage coloring in birds, etc.

Somatic characteristics of individuals, determined by sex, are divided into 3 categories: limited by sex, controlled by sex and linked to sex chromosomes.

Development gender-limited characteristics is caused by genes located in the autosomes of both sexes, but they appear only in individuals of one sex. For example, genes for egg production are present in hens and roosters, but are expressed only in hens. Genes for milk production in cattle and lactation in women and some diseases are inherited similarly (for example, the gout gene appears only in men and its lenetrance is 20%, and in women, as a rule, it does not appear). This phenomenon is due to the influence of the corresponding sex hormones.

Development sex-controlled traits is caused by genes also located in the autosomes of both sexes, but the degree and frequency of their manifestation (expressivity and penetrance) is different in individuals of different sexes. This is especially noticeable in heterozygotes in which a shift in dominance occurs. This is how normal hair growth and baldness are inherited in humans. When two heterozygous individuals marry, we get.

SEXUAL DEVELOPMENT AND SEXUAL BEHAVIOR

(Psychosexual development)

1. The concept of gender. Types of floor.

2. Sexual dimorphism. Primary and secondary sexual characteristics.

3. Sexual development. The concept of sexual differentiation. Sexual differentiation of the brain.

4. Disorders of psychosexual development and behavior.

The concept of field. Types of floor

General biological determination of sex concerns the reproductive aspect and is equally valid for both humans and frogs, chickens, etc. The literature provides different versions of such definitions.

Sex is a set of mutually contrasting generative and related characteristics of individuals of the same species.

Sex is a set of genetic, morphological and physiological characteristics that ensure sexual reproduction.

In a broader human sense, gender is a complex of reproductive, bodily, behavioral and social characteristics that define an individual as a man or a woman. The concept of gender for humans and animals is not identical, because Man is a social being, and sexual relations are not associated only with reproduction. For a person, it is also pleasure, an opportunity to show recognition and love, one of the foundations for building relationships in society.

The following are distinguished: types of floor:

Sexual dimorphism. Primary and secondary sexual characteristics.

Sexual dimorphism refers to the morphological, physiological and psychological differences between representatives of different sexes.

Morphological characteristics of sex These are primary and secondary sexual characteristics. The primary ones are determined genetically (the gonad, external and internal genital organs), and the secondary ones are determined hormonally and appear during puberty, when hormones corresponding to the genetic sex begin to predominate (hair growth of the face, armpits, pubis, the appearance of the Adam's apple, mammary glands, emissions and menstruation, voice mutation, fat deposition and development of the musculoskeletal system according to the female and male type).

Physiological characteristics of sex:

A) the timing of maturation and decline of sexual function is earlier in women than in men;

B) tonic type of activity of the reproductive system in men and cyclic in women;

C) the structure and number of maturing germ cells: women have approximately 450 eggs during the reproductive period, and men have about 200 million sperm during one sexual act;

D) the presence in women of temporary endocrine glands: the corpus luteum (appears in the middle of each cycle) and the placenta (appears during pregnancy;

D) women have higher resistance to stress and genetic invasions (immunity);

E) various forms and degrees of participation in the sexual process (courtship, conception, pregnancy, childbirth, lactation, manifestation of the instinct of motherhood and paternity);

G) presence of orgasm: in men always, in women it may be absent, but this circumstance does not interfere with conception.

Psychological differences more often expressed in behavior. Sexual behavior is the most important secondary sexual characteristic. Differences in behavior occur from birth, i.e. are fixed genetically and do not depend on the predominance of sex-appropriate hormones. Children of preschool age and even the first year of life have sexually significant reactions and behaviors that are caused by sexual desire and not related to it. Psychological differences are also associated with the characteristics of perception and thinking. That's why people sometimes don't understand each other.

Theory of sexual dimorphism formulated in the 60s. 20th century by V.A. Geodakyan. According to this theory, the feminine principle ensures the immutability of offspring from generation to generation, the preservation of the genetic material accumulated during evolution. The feminine principle is the golden storehouse of heredity. Hence the slogan “Women’s health is the health of the nation!”

The male sex is the vanguard of the population, taking upon itself the function of encountering new conditions of existence. The male sex is associated with the formation of new genetic trends under the influence of the environment and their transmission to offspring. The function of collision with environmental conditions and the formation of new genetic trends, and therefore new development options, make the male body more vulnerable and are associated with significant losses. Hence the slogan “Take care of men!” The relationship between the number of male and female individuals at different stages of ontogenesis as follows.

Secondary sexual characteristics develop during puberty. Their appearance is associated with an increase in the level of certain blood hormones (in men, testosterone and its metabolites). Secondary sexual characteristics characterize the maturity of the organism and its gender.

The appearance of secondary sex characteristics

In children before adolescence, sex differences are determined by genetics and the gonads. The normal male chromosome set is 46 XY. This genetics corresponds to the formation in the prenatal period and the further development of the gonads of the testicles and, accordingly, the external genitalia according to the male type.

In childhood (on average up to 8-9 years), there are no other significant physical differences between boys and girls. Then the period of puberty begins, that is. At the onset, the secretion of gonadotropin releasing hormone from the hypothalamus sharply increases. This biologically active substance acts on the pituitary gland. As a result, in this part of the endocrine system the production of gonadotropins increases, which in turn stimulate the gonads.

List of signs

Morphological differences between men and women are especially pronounced in young and middle-aged adults. Some secondary sex characteristics are obvious, while others may be less noticeable. The list of differences includes characteristics of hair, skin, skeletal structure, etc.

List of male secondary sexual characteristics:

• Increase in testicle volume.(cm. ).
• Penis growth.(cm. )
• Pigmentation of the skin of the scrotum.
• . Spermatogenesis.
• Sexual behavior. The ability to experience sexual arousal.
• High growth. Body length depends on many factors (heredity, living conditions, diseases in childhood and adolescence, etc.). In men, growth in general turns out to be higher, since, other things being equal, growth zones close later (due to later puberty). According to the latest data, men in Russia have an average height of 178 cm (which is 12 cm more than women).
• Large body weight. Weight is determined by proportions, developed muscles and high mineral density of bone tissue. For a normosthenic young adult male, 170 cm tall, the average normal weight is about 70 kg (versus 64 kg for women of the same height).
• High skeletal mineral density. In men, bone mass accounts for about 15% of the total weight (versus 10-12% in women). The peak in bone density (at age 30) is more pronounced in men, and the decrease in bone density and strength occurs much more slowly than in women.
• High percentage of muscle tissue. On average, in young and middle-aged men, muscle mass is more than 40-45% of their weight (versus 30-35% in women). The muscles are well developed initially and respond better to physical activity.
• Low percentage of adipose tissue. In men under 60 years of age, fat mass is normally less than 22-25% of total weight. On average, men have 2 times less fat mass than women at the same weight. It is easier for representatives of the stronger sex to lose weight. Losing body weight is possible without significant calorie restriction.
• Abdominal obesity(). This type of excess body weight is characterized by the deposition of fat inside the abdominal cavity. Abdominal obesity is often accompanied by (dyslipidemia, diabetes mellitus, gout).
• Shorter torso and relatively long limbs. This is especially noticeable when measuring height in a sitting position. In men, this height is 5 cm less (with the same body length). The differences mainly appear due to the proportions of the skeleton and the characteristics of the deposition of fatty tissue in the ischial region.
• In men, relatively broad shoulders and narrow pelvis. The body can be schematically depicted as an inverted pyramid.
• Wide chest. On average, boys have a chest circumference that is 10% larger. In men, the chest is longer, that is, it occupies more of the torso than the abdomen.
• Narrow pelvis. The pelvis is narrower (5 cm on average), deeper, the iliac bones are not turned outward, the pelvic cavity is less voluminous, and the dimensions of the inlet and outlet are much narrower. The pelvic bones themselves are thicker and less mobile. Such a pelvis provides reliable support for the internal organs. A narrow pelvis allows men to achieve greater running speed.
• Male skull characterized by relatively large sizes, pronounced brow ridges, occipital protuberances, and a massive lower jaw.
• In men, relatively large pneumatization of the skull bones. Their bones with air spaces (sinuses) are massive, and the sinuses themselves are more voluminous. Pneumatization of the skull bones provides additional protection and thermal insulation.
• Larger teeth with characteristic odontoscopic features. Researchers have also established the fact of gender differences in the size of the alveolar arch and bony palate.
• The shape of the larynx with a developed protrusion(prominentia laryngea). The growth of cartilage forms the so-called Adam's apple, that is, the “Adam's apple.”
• Lower voice tone. Articulation depends on the thickness of the ligaments and the size of the glottis. Voice mutation in young men occurs quite early and accompanies the growth of the larynx.
• Growth of terminal hair on the face and body according to the male pattern. Androgen-dependent areas of hair growth include the skin of the face (chin, skin above the upper lip, sideburns), neck, chest, back, abdomen, shoulders (read).
• Male pattern hair growth in armpits and pubic area(rhombus with one vertex facing the navel).
• . Characteristic baldness of the parietal and frontal areas associated with the action of male sex hormones on the hair follicles.
• In men lumbar lordosis is not pronounced(less curvature of the spine).
• Male posture- representatives of the stronger sex stand straight or lean back somewhat. This feature is formed due to differences in the musculoskeletal system.
• Abdominal (diaphragmatic) type of breathing. In boys and girls in the first year of life, the diaphragmatic type of breathing predominates, then the diaphragmatic-thoracic type is more often observed. From the age of 8-10 years, gender differences appear. In boys, diaphragmatic breathing is established, in girls - chest breathing.
• Relatively large mass of adrenal glands(compared to female ones) with a relatively smaller mass of all other endocrine glands. - organs that help withstand stress, extreme loads and are responsible for behavioral reactions (aggression, fight, defense).
• Men's skin differs in greater thickness (dermis by 15-20%, and the stratum corneum of the epidermis by 40-50%), darker color, greater activity of the sebaceous and sweat glands.

Lack of secondary sexual characteristics in men

Secondary sexual characteristics appear during puberty. The timing of this period in the life of each person is individual.

Delayed puberty is said to occur if a boy does not have any secondary sexual characteristics by the age of 14 years.

Such teenagers are recommended to be examined by a pediatrician, endocrinologist, urologist and andrologist. In addition, medical care may be required for those young men who, 4.5 years after the onset of puberty, have not reached the 5th (final) stage of sexual development, that is, full maturity.

Endocrinologist Tsvetkova I. G.

Secondary sexual characteristics are clearly expressed not only in humans, but also in animals. These characteristics are of great importance either in attracting an individual of the opposite sex or in fighting for it. Primary sexual characteristics include the gonads and genitals. Secondary - develops during puberty under the influence of sex hormones.

Dependence of secondary sexual characteristics on primary ones

There is a direct dependence of secondary sexual characteristics on primary ones. Their development is greatly influenced by sex hormones, and they begin to be produced during puberty. During this period changes occur:

• musculoskeletal system;
• subcutaneous fat;
• body proportions;
• hairline;
• behavioral characteristics;
• mammary glands;
• voice timbre.

Dependent secondary sex characteristics are also called eusexual and develop together with the gonads. And independent characteristics (pseudosexual) develop independently of the function of the gonads.

Female secondary sexual characteristics

Female sex hormones influence a fairly rapid increase in height and body weight. It is worth noting that the growth of the limbs occurs much faster than the body. The shape of the skeleton and especially the pelvis changes. The figure also changes mainly in the area of ​​the buttocks, thighs and abdomen, body shapes are rounded, and the skin becomes softer and thinner. The mass of adipose tissue increases. Increases female-type hair growth. Menstruation begins. All this refers to secondary sexual characteristics.

In girls, active growth of the mammary glands begins, as a result of which the nipple circles darken quite strongly, and the nipples also enlarge. As the breasts enlarge, adipose tissue accumulates in them, which leads to the final formation of a mature mammary gland.

Male secondary sexual characteristics

Secondary sexual characteristics of boys are manifested in more active body growth and an increase in muscle mass. Formation of a narrower pelvis with broad shoulders.

In men, the shape of the larynx changes, the voice becomes rough and low, and an Adam's apple appears. A beard and mustache begin to grow, men are characterized by more body hair, and the hair is distributed according to the male type: on the face, on the chest, on the stomach, etc.