The human endocrine apparatus and its age characteristics. Course of lectures on

Endocrine glands. The endocrine system plays an important role in the regulation of body functions. The organs of this system are endocrine glands- secrete special substances that have a significant and specialized effect on the metabolism, structure and function of organs and tissues. Endocrine glands differ from other glands that have excretory ducts (exocrine glands) in that they secrete the substances they produce directly into the blood. Therefore they are called endocrine glands (Greek endon - inside, krinein - to highlight).

The endocrine glands include the pituitary gland, pineal gland, pancreas, thyroid gland, adrenal glands, genital, parathyroid or parathyroid glands, thymus (goiter) gland.

Pancreas and gonads - mixed, since part of their cells performs an exocrine function, the other part - intrasecretory. The sex glands produce not only sex hormones, but also germ cells (eggs and sperm). Some cells of the pancreas produce the hormone insulin and glucagon, while other cells produce digestive and pancreatic juice.

The human endocrine glands are small in size, have a very small mass (from fractions of a gram to several grams), and are richly supplied with blood vessels. Blood brings to them the necessary building material and carries away chemically active secrets.

An extensive network of nerve fibers approaches the endocrine glands, their activity is constantly controlled by the nervous system.

The endocrine glands are functionally closely related to each other, and the defeat of one gland causes a dysfunction of other glands.

Thyroid. In the process of ontogenesis, the mass of the thyroid gland increases significantly - from 1 g in the neonatal period to 10 g by 10 years. With the onset of puberty, the growth of the gland is especially intense, during the same period the functional tension of the thyroid gland increases, as evidenced by a significant increase in the content of total protein, which is part of the thyroid hormone. The content of thyrotropin in the blood increases intensively up to 7 years.

An increase in the content of thyroid hormones is noted by the age of 10 and at the final stages of puberty (15-16 years). At the age of 5-6 to 9-10 years, the pituitary-thyroid relationship changes qualitatively; the sensitivity of the thyroid gland to thyroid-stimulating hormones decreases, the highest sensitivity to which was noted at 5-6 years. This indicates that the thyroid gland is especially important for the development of the organism at an early age.

Insufficiency of thyroid function in childhood leads to cretinism. At the same time, growth is delayed and the proportions of the body are violated, sexual development is delayed, mental development lags behind. Early detection of hypothyroidism and appropriate treatment has a significant positive effect.

Adrenals. The adrenal glands from the first weeks of life are characterized by rapid structural transformations. The development of adrenal measles proceeds intensively in the first years of a child's life. By the age of 7, its width reaches 881 microns, at the age of 14 it is 1003.6 microns. The adrenal medulla at the time of birth is represented by immature nerve cells. They quickly differentiate during the first years of life into mature cells, called chromophilic, as they are distinguished by the ability to stain yellow with chromium salts. These cells synthesize hormones, the action of which has much in common with the sympathetic nervous system - catecholamines (adrenaline and norepinephrine). Synthesized catecholamines are contained in the medulla in the form of granules, from which they are released under the action of appropriate stimuli and enter the venous blood flowing from the adrenal cortex and passing through the medulla. The stimuli for the entry of catecholamines into the blood are excitation, irritation of the sympathetic nerves, physical activity, cooling, etc. The main hormone of the medulla is adrenalin, it makes up about 80% of the hormones synthesized in this section of the adrenal glands. Adrenaline is known as one of the fastest acting hormones. It accelerates the circulation of blood, strengthens and speeds up heart contractions; improves pulmonary respiration, expands the bronchi; increases the breakdown of glycogen in the liver, the release of sugar into the blood; enhances muscle contraction, reduces their fatigue, etc. All these effects of adrenaline lead to one common result - the mobilization of all the forces of the body to perform hard work.

Increased secretion of adrenaline is one of the most important mechanisms of restructuring in the functioning of the body in extreme situations, during emotional stress, sudden physical exertion, and cooling.

The close connection of the chromophilic cells of the adrenal gland with the sympathetic nervous system causes the rapid release of adrenaline in all cases when circumstances arise in a person's life that require an urgent effort from him. A significant increase in the functional tension of the adrenal glands is observed by the age of 6 and during puberty. At the same time, the content of steroid hormones and catecholamines in the blood increases significantly.

Pancreas. In newborns, intrasecretory pancreatic tissue predominates over exocrine pancreatic tissue. The islets of Langerhans increase significantly in size with age. Islets of large diameter (200-240 microns), characteristic of adults, are found after 10 years. An increase in the level of insulin in the blood in the period from 10 to 11 years was also established. The immaturity of the hormonal function of the pancreas may be one of the reasons that diabetes mellitus is detected in children most often between the ages of 6 and 12, especially after acute infectious diseases (measles, chicken pox, mumps). It is noted that the development of the disease contributes to overeating, especially the excess of carbohydrate-rich food.

There is hardly any complex mechanism that works as smoothly as the body of a healthy person. This coherence of the body's work is ensured by the central nervous system through the nerve pathways and special organs called endocrine glands. Organs are called glands which produce and secrete some substances: digestive juices, sweat, sebum, milk, etc. The substances secreted by the glands are called secrets. Secrets are secreted through the excretory ducts to the surface of the body or to the mucous membrane of internal organs.

Endocrine glands- these are glands of a special kind, they do not have excretory ducts; their secret, called a hormone, is secreted directly into the blood. That's why they called endocrine glands or, otherwise, endocrine glands. Getting into the blood, hormones are carried to all human organs and have their own special, characteristic for each gland or, as they say, specific effect on them.

As long as the endocrine glands function normally, they do not remind of their existence in any way, the human body works in a harmonious, balanced way. We notice them only when, due to significant deviations in the activity of one or another gland, and sometimes several glands, the balance in the body is simultaneously disturbed.

Functions of the endocrine glands and their disorders

To understand how important the role of the whole body of an adult and child play endocrine glands Let's get acquainted with the main ones and with their characteristics functions(see picture).

Thyroid - one of the most important endocrine glands. In the normal state, it is not visible, and only when enlarged does it form a protrusion on the front surface of the neck, noticeable to the eye, especially at the time of swallowing. Often, with its large size, with the so-called goiter, there is a decrease in the function of the gland. Especially often there is such a discrepancy between the large size and weak function of the gland in mountainous places and other areas, the nature of which (earth, water, plants) contains only negligible amounts of iodine necessary for the formation thyroxine. The introduction of iodine into the body can prevent the development of goiter and enhance the function of the gland. This is what is done in the areas of goiter distribution: iodine is added to the salt.

With a lack of thyroxine disorders occur in the body, characterized by growth retardation, dryness and thickening of the skin, impaired bone development, muscle weakness and significant mental retardation, which usually manifests itself already in childhood. The extreme degree of these disorders, observed in the absence of the function of a prominent gland, is called myxedema. In this case, the child is injected with thyroid preparations.

An increase in the function of the gland also leads to severe phenomena. The excitatory effect exerted by thyroxin on the central nervous system becomes excessive. Such a state is called thyrotoxicosis. In severe forms of thyrotoxicosis (the so-called Basedow's disease), emaciation, palpitations are observed, nervous excitability sharply increases, violated sleep, bulging eyes appear. In these cases, treatment is aimed at suppressing the activity of the thyroid gland, sometimes resorting to its removal.

Pituitary(or an appendage of the brain) - a small, but playing a large role in the body of endocrine iron. Pituitary hormones affect human growth, the development of the skeleton and muscles. With its insufficient function, growth is sharply delayed and a person can remain a dwarf; delayed and stops sexual development. With increased activity of certain pituitary cells, giant growth occurs; if the growth of a person has already ended, there is an increase in individual bones (face, hands, feet), and sometimes other parts of the body (tongue, auricles), which is called acromegaly. Violations the activity of the pituitary gland can cause other changes.

adrenal glands - a pair of small glands located above the kidneys, hence their name. The adrenal gland secretes hormones that affect the metabolism in the body and enhance the function of the sex glands; It also produces the hormone adrenaline, which plays an important role in the proper functioning of the cardiovascular system and has a number of other functions.

Goiter, or thymus, gland (has nothing to do with goiter - enlargement of the thyroid gland), is most active in childhood. Her hormone promotes the growth of the child, with the onset of puberty, it decreases and gradually atrophies. This gland is located behind the sternum and partially covers the anterior surface of the heart.

Pancreas , which got its name due to its location slightly below the stomach and behind it in the bend of the duodenum, is not only an endocrine gland. It is one of the most important digestive glands. In addition to the cells that secrete digestive juice, it also includes special islands, consisting of cells that secrete a hormone that is very important for normal metabolism. This is insulin, which promotes the absorption of sugar. With a decrease in the hormonal function of the pancreas, diabetes develops. Until insulin was discovered and a way to obtain it was found, it was difficult for such patients to help; at present, the introduction of insulin restores their ability to absorb carbohydrates, and at the same time increases their overall performance.

gonads have both external and intrasecretory function. In addition to the formation of special germ cells necessary for reproduction, they also secrete hormones that determine the external, so-called secondary sexual characteristics characteristic of each sex (growth of hair on the pubis and armpits, and later - and only in boys - on the face, breast enlargement in girls, etc.) and a number of others age features characteristic of one gender or another. In the first period of childhood, these glands almost do not function. Their function sometimes begins to affect from the age of 7-8 and especially increases during puberty (in girls from 11-13, in boys from 13-15 years).

The normal function of the sex glands is very important for the full development of a person. The hormones of the gonads through the nervous system affect the metabolism of the child and activate the development of his physical and spiritual strength. The period of sexual development is also the period of active formation of a person's personality.

Such is the general characteristic of the functions of the human endocrine glands, their role in the physiological, normal activity of the body.

Endocrine glands of a child: features of development

Endocrine glands direct child development from early years of life. They function with different intensity in different periods of human life. For each age period characterized by the predominance of the activities of one group or another child's endocrine glands.

For the age of up to 3-4 years, the most intensive function of the thymus gland, which regulates growth, is characteristic. Growth is also enhanced by thyroid hormones, which function very actively in the period from 6 months to 2 years, and the pituitary gland, whose activity increases after 2 years.

At the age of 4 to 11 years, the pituitary and thyroid glands remain active, the activity of the adrenal glands increases, and at the end of this period, the sex glands also turn on. This is a period of relative balance in the activity of the endocrine glands.

In the next period - adolescence - the balance is disturbed. This age is characterized sometimes gradually, and sometimes rapidly growing hormonal activity of the sex glands, a significant increase in the function of the pituitary gland; under the influence of the pituitary hormone, increased bone growth (stretching) occurs; violation of the proportionality of growth leads to angularity, clumsiness, often observed in adolescents. The activity of the thyroid gland and adrenal glands is also significantly enhanced. The thyroid gland, increasing, sometimes becomes noticeable to the eye; in the absence of significant disorders characteristic of thyrotoxicosis, a slight increase in the gland can be considered physiological, corresponding to the age-related characteristics of this period.

Restructuring in the work of the endocrine glands has a great influence on the development of the body and especially on its nervous system. If these processes develop proportionally, then the responsible transitional period of a person's life proceeds calmly. In violation of proportionality in endocrine activity, a kind of "crisis" often occurs. The nervous system and psyche of the child become vulnerable: irritability, incontinence in behavior, fatigue, and a tendency to tears appear. Gradually, with the appearance of secondary sexual characteristics, adolescence passes into adolescence, balance is restored in the body.

Parents need to know age-related features of the development of the endocrine apparatus (endocrine glands) of a child and adolescent in order to notice possible deviations in time and take the necessary measures. School age, the beginning of a person's independent working life, requires special attention. The coincidence of this period with a serious restructuring of the neuro-endocrine apparatus makes it even more responsible.

Prevention of endocrine diseases in children

Maintaining balance in the body, which ensures the child's normal development and performance, largely depends on the parents:

Avoid unnecessary excitation of the child's nervous system, protect it from unnecessary stimuli. This, of course, does not mean that the child should be unloaded from schoolwork or the preparation of lessons necessary for him. According to age, involve children in helping with household services for the family. Make sure that work processes alternate correctly with rest, entertainment, sleep, and nutrition.
It is very important to allocate sufficient time for the child to be outdoors and for sleep, which provides a complete rest of the nervous system. In the first grades of the school - sleep for at least 10 hours, and in the future, sleep time gradually decreases to 8.5 hours a day.
Always go to bed and wake up at the same time, but not too late.
Avoid excessive irritants before going to bed: do not read until late, especially while lying in bed, resolutely avoid excessive use of the TV and computer.
Greater value in prevention of endocrine diseases in children also has food. The child's food should be complete, contain a sufficient amount of proteins and other nutrients, in particular vitamins.
Remember the leading role of the central nervous system in the work of the endocrine glands. Protect the child from mental trauma, often leading to a breakdown in the balance in the endocrine glands.
Making certain demands on the child, try to mobilize his will, instill in him how important a conscientious attitude to studies, organization in everyday life are. It is essential that parents themselves be an example of such organization and that they show calmness and restraint in dealing with adolescents.

In the event of the appearance of the endocrine disorders described above (especially if they appeared in the late period of childhood and are not pronounced), the regulation of the regimen and nutrition of the child, the strengthening of his nervous system by physical education methods usually lead to the restoration of the normal functioning of the endocrine glands.

In more severe cases of dysfunction of the endocrine glands, treatment with endocrine gland preparations or other methods of treatment is required: medicinal, physiotherapeutic and even surgical. In such cases, contact your doctor, who will be able to give a correct assessment of the child's condition, prescribe treatment, and refer you to an endocrinologist.

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General characteristics of the endocrine glands in children and adolescents

The endocrine glands form the endocrine system, which, along with the nervous system, has a regulatory effect on the human body. Endocrine glands are called organs in which a secret is formed that specifically affects various functions of the body. The secret of the endocrine glands is called hormones (biologically active substances). Unlike other glands, the endocrine glands do not have excretory ducts and their secretion is excreted into the blood or lymph. Based on this principle, the endocrine glands are called endocrine glands. The endocrine glands (HWS) include:

1) pituitary gland,

2) thyroid,

3) parathyroid,

4) forked,

5) adrenal glands,

6) epiphysis,

7) pancreas and 8) genital.

The pituitary, thyroid, parathyroid and adrenal glands have only internal secretion. The pancreas and genital organs are characterized by mixed secretion: they not only produce hormones, but also secrete substances that do not have hormonal activity.

Hormones affect every function of the body. They

1) regulate metabolism (protein, carbohydrate, fat, mineral, water);

2) maintain homeostasis (self-regulation of the constancy of the internal state);

3) affect the growth and formation of organs, organ systems and the whole organism as a whole;

4) under the influence of hormones, tissue differentiation is carried out;

5) they can change the intensity of the functioning of any organ.

All hormones have specific actions. Phenomena that occur with insufficiency of one of the glands may disappear when treated with hormones of the same gland. Thus, disorders of carbohydrate metabolism can be eliminated only by the hormones of the same gland, insulin. All hormones can act on certain organs located at a great distance from the place of excretion. For example, the pituitary gland is located in the cranial cavity, and its hormone acts on many organs, including the sex glands located in the pelvic cavity. Hormones have an effect in very small concentrations, i.e. their biological activity is very high. Thus, hormones have a number of properties:

Formed in small quantities.

They have high biological activity.

They have a strict specificity of action.

They have a remote action.

Research in recent years has led to the creation of hypotheses regarding the mechanism of action of hormones. It is not the same for different hormones. It is believed that hormones act on target cells by changing the physical structure of enzymes, the permeability of the cell membrane, and affecting the genetic apparatus of the cell. According to the first hypothesis, when hormones join enzymes, they change their structure, which affects the rate of enzymatic reactions. Hormones can activate or inhibit the action of enzymes. This mechanism has been proven only for some of the hormones. Similarly, not all hormones have been shown to have an effect on cell membrane permeability. The effect of insulin, a pancreatic hormone, on the permeability of the cell membrane with respect to glucose has been well studied. It has now been proven that almost all hormones are characterized by action through the genetic apparatus.

All VVS in the whole organism are in constant interaction. Pituitary hormones regulate the functioning of the thyroid gland, pancreas, adrenal glands, and sex glands. The hormones of the gonads affect the work of the goiter, and the hormones of the goiter - on the gonads, etc. The interaction is manifested in the fact that the reaction of one or another organ is often carried out only with the sequential action of a number of hormones. Interaction can also be carried out through the nervous system. The hormones of some glands act on the nerve centers, and the impulses coming from the nerve centers change the nature of the activity of other glands.

Hormones are essential in maintaining relative physical and chemical constancy the internal environment of the body, called homeostasis. The maintenance of homeostasis is facilitated by humoral regulation of functions, which manifests the ability to activate or inhibit the functional activity of organs and systems. .

In the body, humoral and nervous regulation of functions are closely interrelated. On the one hand, there are many biologically active substances that can affect the vital activity of nerve cells and the functions of the nervous system, on the other hand, the synthesis and release of humoral substances into the blood is regulated by the nervous system. Thus, in the body there is a single neuro-humoral regulation of functions that provides the ability for self-regulation of life.

For example, male sex hormones androgens affect the occurrence of sexual reflexes associated with the activity of the nervous system. The nervous system through the senses, in turn, gives signals about the production of sex hormones at the right time.

The hypothalamus plays an important role in the integration of the nervous and endocrine systems. This property is due to the close connection of the hypothalamus with the pituitary gland. The hypothalamus has a very significant effect on the production of pituitary hormones. Large neurons of the hypothalamus are secretory cells, the hormone of which travels along the axons to the posterior lobe of the pituitary gland. The vessels surrounding the nuclei of the hypothalamus, uniting into the portal system, descend to the anterior lobe of the pituitary gland, supplying the cells of this part of the gland. From both lobes of the pituitary gland, its hormones through the vessels enter the endocrine glands, whose hormones, in turn, in addition to affecting peripheral tissues, also affect the hypothalamus and the anterior pituitary gland, thereby regulating the need for the release of various pituitary hormones in one or another amount.

Endocrine influences change reflexively: impulses from proprioreceptors, pain irritation, emotional factors, mental and physical stress affect the secretion of hormones.

Age features of the endocrine glands

Weight pituitary gland newborn child is 100 - 150 mg. In the second year of life, its increase begins, which turns out to be sharp at the age of 4-5, after which a period of slow growth begins until the age of 11. By the period of puberty, the mass of the pituitary gland averages 200-350 mg, and by the age of 18-20 - 500-650 mg. Up to 3-5 years, the amount of GH is released more than in adults. From 3-5 years old, the rate of GH release is equal to adults. In newborns, the amount of ACTH is equal to adults. TSH is released abruptly immediately after birth and before puberty. Vasopressin is maximally secreted by the first year of life. The greatest intensity of the release of gonadotropic hormones is observed during puberty.

iron homeostasis internal secretion

The newborn has a mass thyroidglands fluctuates from 1 to 5 g. it decreases slightly by 6 months, and then a period of rapid increase begins, which lasts up to 5 years. During puberty, the increase continues and reaches the mass of the gland of an adult. The greatest increase in hormone secretion is observed during early childhood and puberty. The maximum activity of the thyroid gland is reached at 21-30 years.

After the birth of a child, maturation occurs parathyroidglands, which is reflected in the increase with age in the amount of secreted hormone. The greatest activity of the parathyroid glands is noted in the first 4-7 years of life.

The newborn has a mass adrenal glands is approximately 7 years. The growth rate of the adrenal glands is not the same in different age periods. A particularly sharp increase is observed at 6-8 months. and 2-4 g. The increase in the mass of the adrenal glands continues up to 30 years. The medulla appears later than the cortex. After 30 years, the amount of adrenal hormones begins to decrease.

By the end of 2 months of intrauterine development, rudiments appear in the form of outgrowths pancreasglands. The head of the pancreas in an infant is raised slightly higher than in adults and is located at about 10-11 thoracic vertebrae. The body and tail go to the left and slightly rise up. It weighs a little less than 100 g in an adult. At birth, iron weighs only 2-3 g in babies, has a length of 4-5 cm. By 3-4 months, its mass increases by 2 times, by 3 years it reaches 20 g, and by 10-12 years - 30 g. Resistance to glucose load in children under 10 years of age is higher, and the absorption of food glucose is faster than in adults. This explains why children love sweets and consume them in large quantities without danger to health. With age, the insular activity of the pancreas decreases, so diabetes most often develops after 40 years.

In early childhood in thymusgland the cortex predominates. During puberty, the amount of connective tissue increases in it. In adulthood, there is a strong proliferation of connective tissue.

The mass of the epiphysis at birth is 7 mg, and in an adult - 100-200 mg. The increase in the size of the epiphysis and its mass lasts up to 4-7 years, after which it undergoes reverse development.

Bibliography

1. Anatomy and age-related physiology, Educational manual. - Komsomolsk-on-Amur, 2004.

2. Badalyan L.O., Children's neurology. - M, 1994.

3. Leontyeva N.N., Marinova V.V., Anatomy and physiology of the child's body. - M, 1986.

4. S. G. Mamontov, Biology. - M, 1991.

5. Mikheev V.V., Melnichuk P.V., Nervous diseases. - M, 1991

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The endocrine system is endocrine glands that secrete physiologically active substances into the body and do not have excretory ducts. Functions of hormones in the human body. The structure of the hypothalamus and pituitary gland. Diabetes insipidus. Epithelial body.

The endocrine glands include the pituitary gland, pineal gland, pancreas, thyroid gland, adrenal glands, genital, parathyroid or parathyroid glands, thymus (goiter) gland.

An extensive network of nerve fibers approaches the endocrine glands, their activity is constantly controlled by the nervous system.

The endocrine glands are functionally closely related to each other, and the defeat of one gland causes a dysfunction of other glands.

9. AGE FEATURES OF THE GENERAL GLANDS Male and female gonads (testes and ovaries), having formed during fetal development, undergo slow morphological and functional maturation after birth. The mass of the testicle in newborns is 0.3 G, in 1 year - 1 G, at the age of 14 - 2 G, at 15-16 years old - 8 G, at 19 years old - 20 G . The seminiferous tubules in newborns are narrow, over the entire period of development their diameter increases by 3 times. The ovaries are laid above the pelvic cavity, and in the newborn the process of their lowering has not yet been completed. They reach the cavity of the small pelvis in the first 3 weeks after birth, but only by the age of 1-4 years their position, characteristic of an adult, is finally established. The mass of the ovary in a newborn is 5-6 g, and it changes little during subsequent development: in an adult, the mass of the ovary is 6-8 g. In old age, the mass of the ovary decreases to 2 g. In the process of sexual development, several periods are distinguished: children - up to 8 -10 years old, adolescence - from 9-10 to 12-14 years old, youthful - from 13-14 to 16-18 years old, puberty - up to 50-60 years old and menopause - the period of extinction of sexual function. During childhood in the ovary In girls, primordial follicles grow very slowly, in which in most cases the membrane is still absent. In boys, the seminiferous tubules in the testes are slightly convoluted. In, urine, regardless of gender, contains a small amount of androgens and estrogens, which are formed during this period in the adrenal cortex. The content of androgen in the blood plasma of children of both sexes immediately after birth is the same as in young women. Then it decreases to very low figures (sometimes to 0) and remains at this level until 5-7 years. During adolescence, graafian vesicles appear in the ovaries, follicles grow rapidly. The seminiferous tubules in the testes increase in size, along with spermatogonia, spermatocytes appear. During this period, in boys, the amount of androgens in the blood plasma and in the urine increases; girls have estrogen. Their number increases even more in adolescence, which leads to the development of secondary sexual characteristics. During this period, the periodicity inherent in the female body in the amount of secreted estrogens appears, which ensures the female sexual cycle. A sharp increase in estrogen secretion coincides in time with ovulation, after which, in the absence of fertilization, menstruation occurs, which is called the release of the decaying uterine mucosa along with the contents of the uterine glands and blood from the vessels that open at the same time. Strict cyclicity in the amount of estrogen released and, accordingly, in the changes that take place in the ovary and uterus, is not immediately established. The first months of sexual cycles may not be regular. With the establishment of regular sexual cycles, the period of puberty begins, lasting for women up to 45-50 years, and for men, on average, up to 60 years. The period of puberty in women is characterized by the presence of regular sexual cycles: ovarian and uterine.

Puberty

The concept of puberty. The gonads and related signs of sex, being laid in the prenatal period, are formed throughout the entire period of childhood and determine sexual development. Sex glands, their functions are inextricably linked with the holistic process of child development. At a certain stage of ontogenesis, sexual development accelerates sharply and physiological sexual maturity sets in. The period of accelerated sexual development and the achievement of puberty is called period of puberty. This period occurs mainly during adolescence. The puberty of girls is 1-2 years ahead of the puberty of boys, and there is also a significant individual variation in the timing and rate of puberty.

The timing of the onset of puberty and its intensity are different and depend on many factors: health status, diet, climate, living and socio-economic conditions. An important role is played by hereditary features.

Unfavorable living conditions, defective food, lack of vitamins in it, severe or repeated diseases lead to a delay in puberty. In big cities, puberty of adolescents usually occurs earlier than in rural areas.

During puberty, profound changes occur in the body. Changes in the relationship of the endocrine glands and, above all, the hypothalamic-pituitary system. The structures of the hypothalamus are activated, the neurosecretions of which stimulate the release of tropic hormones from the pituitary gland.

Under the influence of pituitary hormones, body growth in length increases. The pituitary gland also stimulates the activity of the thyroid gland, which is why, especially in girls, the thyroid gland noticeably increases during puberty. The increased activity of the pituitary gland leads to an increase in the activity of the adrenal glands, the active activity of the gonads begins, the increasing secretion of sex hormones leads to the development of the so-called secondary sexual characteristics - physique, body hair, voice timbre, development of the mammary glands. The gonads and the structure of the genital organs are classified as primary sexual characteristics.

stages of puberty. Puberty is not a smooth process; certain stages are distinguished in it, each of which is characterized by the specifics of the functioning of the endocrine glands and, accordingly, of the whole organism as a whole. The stages are determined by the combination of primary and secondary sexual characteristics. Both in boys and girls, there are 5 stages of puberty.

Stage I - pre-puberty (the period immediately preceding puberty). It is characterized by the absence of secondary sexual characteristics.

Stage II - the beginning of puberty. In boys, a slight increase in the size of the testicles. Minimal pubic hair. Hair is sparse and straight. Girls have swelling of the mammary glands. Slight hair growth along the labia. At this stage, the pituitary gland is sharply activated, its gonadotropic and somatotropic functions increase. The increase in the secretion of somatotropic hormone at this stage is more pronounced in girls, which determines the increase in their growth processes. The secretion of sex hormones increases, the function of the adrenal glands is activated.

Stage III - in boys, a further increase in the testicles, the beginning of an increase in the penis, mainly in length. Pubic hair becomes darker, coarser, begins to spread to the pubic joint. In girls, the further development of the mammary glands, hair growth spreads towards the pubis. There is a further increase in the content of gonadotropic hormones in the blood. The function of the sex glands is activated. In boys, increased secretion of somatotropin determines accelerated growth.

IV stage. In boys, the penis increases in width, the voice changes, juvenile acne appears, facial hair, axillary and pubic hair begin. In girls, the mammary glands intensively develop, hair growth is of an adult type, but less common. At this stage, androgens and estrogens are intensively released. Boys retain a high level of somatotropin, which determines a significant growth rate. In girls, the content of somatotropin decreases and the growth rate decreases.

Stage V - in boys, the genitals and secondary sexual characteristics finally develop. In girls, the mammary glands and sexual hairs correspond to those of an adult woman. At this stage, menstruation stabilizes in girls. The appearance of menstruation indicates the beginning of puberty - the ovaries are already producing mature eggs ready for fertilization.

Menstruation lasts 2 to 5 days on average. During this time, about 50-150 cm 3 of blood is released. If menstruation is established, then they are repeated approximately every 24-28 days. The cycle is considered normal when menstruation occurs at regular intervals, lasts the same number of days with the same intensity. At first, menstruation can last 7-8 days, disappear for several months, for a year or more. Only gradually is a regular cycle established. In boys, spermatogenesis reaches full development at this stage.

During puberty, especially at stages II-III, when the function of the hypothalamic-pituitary system, the leading link in endocrine regulation, is dramatically rebuilt, all physiological functions undergo significant changes.

The intensive growth of the skeletal skeleton and muscular system in adolescents does not always keep pace with the development of internal organs - the heart, lungs, gastrointestinal tract. The heart outstrips the blood vessels in growth, as a result of which blood pressure rises and makes it difficult, first of all, the work of the heart itself. At the same time, the rapid restructuring of the whole organism, which occurs during puberty, in turn, makes increased demands on the heart. And insufficient work of the heart (“youthful heart”) often leads to dizziness, blueness and cold extremities in boys and girls. Hence the headaches, and fatigue, and periodic bouts of lethargy; often in adolescents there is a fainting state due to spasms of the cerebral vessels. With the end of puberty, these disorders usually disappear without a trace.

Significant changes at this stage of development in connection with the activation of the hypothalamus undergo the functions of the central nervous system. The emotional sphere is changing: the emotions of adolescents are mobile, changeable, contradictory: hypersensitivity is often combined with callousness, shyness with deliberate swagger, excessive criticism and intolerance towards parental care are manifested. During this period, there is sometimes a decrease in efficiency, neurotic reactions, irritability, tearfulness (especially in girls during menstruation).

CONCLUSION

In periods of development before reaching adulthood, it develops most intensively, a person grows and during these periods parents should especially closely monitor their children, if the necessary measures are not taken during these periods, then the consequences will be unpleasant, both for the child himself and for his parents . The most difficult periods for parents are the “newborn”, “breast” and “teenage”.

In the first two periods, the body is only becoming, and it is not known how it will develop - after all, it is still weakened and not ready for life.

In "teenage" the personality of a teenager is intensively formed, a feeling of growing up arises, attitudes towards members of the opposite sex change.

During the transitional period, children need a particularly sensitive attitude from parents and teachers. You should not specifically draw the attention of adolescents to complex changes in their body, psyche, however, it is necessary to explain the regularity and biological meaning of these changes. The art of the educator in these cases is to find such forms and methods of work that would switch the children's attention to various and diverse types of activity, distract them from sexual experiences. This is, first of all, increasing the requirements for teaching, work and behavior of schoolchildren.

At the same time, a tactful, respectful attitude of adults towards the initiative and independence of adolescents, the ability to direct their energy in the right direction is very important. After all, teenagers tend to overestimate their strengths and the measure of their independence. This is also one of the features of the transition period. 12. Literature:

1. Anatomy and physiology of the child's body: (Fundamentals of the doctrine of the cell and the development of the body, the nervous system, musculoskeletal apparatus): A textbook for students of ped. in-t on spec. "Pedagogy and psychology". / Ed. Leontyeva N.N., Marinova K.V. - 2nd ed. revised - M .: Education, 1986.

2. Anatomy and physiology of the child's body: (Internal organs) ” / Ed. Leontyeva N.N., Marinova K.V. - M.: Enlightenment, 1976

3. Age physiology and school hygiene: A guide for ped students. institutions” / Ed. Khripkova A.G. etc. - M.: Enlightenment, 1990

4. The endocrine system of a growing organism: Textbook for universities / Ed. Drzhevetskoy I.A - M .: Higher School, 1987.

LECTURE COURSE ON

age physiology

Pituitary

The pituitary gland is of ectodermal origin. The anterior and middle (intermediate) lobes are formed from the epithelium of the oral cavity, the neurohypophysis (posterior lobe) - from the diencephalon. In children, the anterior and middle lobes are separated by a gap, over time it overgrows and both lobes are closely adjacent to each other.

The endocrine cells of the anterior lobe differentiate in the embryonic period, and at the 7-9th week they are already capable of synthesis of hormones.

The mass of the pituitary gland of newborns is 100-150 mg, and the size is 2.5-3 mm. In the second year of life, it begins to increase, especially at the age of 4-5 years. After that, until the age of 11, the growth of the pituitary gland slows down, and from the age of 11 it accelerates again. By the period of puberty, the mass of the pituitary gland averages 200-350 mg, by 18-20 years - 500-600 mg. The diameter of the pituitary gland by adulthood reaches 10-15 mm.

Pituitary hormones: functions and age-related changes

Hormones that control the function of peripheral endocrine glands are synthesized in the anterior pituitary gland: thyroid-stimulating, gonadotropic, adrenocorticotropic, as well as somatotropic hormone (growth hormone) and prolactin. The functional activity of the adenohypophysis is fully regulated by neurohormones; it does not receive nervous influences from the central nervous system.

Somatotropic hormone (somatotropin, growth hormone) - STH determines the growth processes in the body. Its formation is regulated by the hypothalamic GH-releasing factor. This process is also influenced by pancreatic and thyroid hormones, adrenal hormones. Factors that increase the secretion of growth hormone include hypoglycemia (lowering blood glucose levels), fasting, certain types of stress, intense physical work. The hormone is also released during deep sleep. In addition, the pituitary gland episodically secretes large amounts of GH in the absence of stimulation. The biological effect of growth hormone is mediated by somatomedin, which is formed in the liver. STH receptors (i.e. structures with which the hormone directly interacts) are built into cell membranes. The main role of STH is the stimulation of somatic growth. Its activity is associated with the growth of the skeletal system, an increase in the size and mass of organs and tissues, protein, carbohydrate and fat metabolism. STH acts on many endocrine glands, kidneys, and on the functions of the immune system. As a growth stimulator at the tissue level, GH accelerates the growth and division of cartilage cells, the formation of bone tissue, promotes the formation of new capillaries, and stimulates the growth of epiphyseal cartilage. The subsequent replacement of cartilage with bone tissue is provided by thyroid hormones. Both processes are accelerated under the influence of androgens, STH stimulates the synthesis of RNA and proteins, as well as cell division. There are gender differences in the content of growth hormone and indicators of the development of muscles, skeletal system and fat deposition. An excess amount of growth hormone disrupts carbohydrate metabolism, reducing the use of glucose by peripheral tissues, and contributes to the development of diabetes. Like other pituitary hormones, growth hormone contributes to the rapid mobilization of fat from the depot and the entry of energy material into the blood. In addition, there may be a delay in extracellular water, potassium and sodium, and a violation of calcium metabolism is also possible. An excess of the hormone leads to gigantism (Fig. 3.20). This accelerates the growth of the bones of the skeleton, but an increase in the secretion of sex hormones upon reaching puberty stops it. Increased secretion of growth hormone is possible in adults. In this case, there is an increase in the extremities of the body (ears, nose, chin, teeth, fingers, etc.). bone growths can form, and the size of the digestive organ (tongue, stomach, intestines) can also increase. This pathology is called acromegaly and is often accompanied by the development of diabetes.

Children with insufficient secretion of growth hormone develop into dwarfs of a "normal" physique (Fig. 3.21). Growth retardation appears after 2 years, but intellectual development is usually not impaired.

The hormone is determined in the pituitary gland of a 9-week-old fetus. In the future, the amount of growth hormone in the pituitary gland increases and by the end of the prenatal period increases by 12,000 times. In the blood, STH appears at the 12th week of intrauterine development, and in 5-8-month-old fetuses it is about 100 times more than in adults. The concentration of growth hormone in the blood of children continues to be high, although during the first week after birth it decreases by more than 50%. By 3-5 years of age, the level of GH is the same as in adults. In newborns, growth hormone is involved in the immune defense of the body, affecting lymphocytes.

STG ensures the normal physical development of the child. Under physiological conditions, the secretion of the hormone is episodic. In children, STH is secreted 3-4 times during the day. Its total amount released during deep night sleep is much greater than in adults. In connection with this fact, the need for proper sleep for the normal development of children becomes obvious. With age, the secretion of GH decreases.

The growth rate in the prenatal period is several times greater than in the postnatal period, but the influence of the endocrine glands on this process is not of decisive importance. It is believed that the growth of the fetus is mainly under the influence of placental hormones, factors of the maternal organism and depends on the genetic program of development. The cessation of growth occurs, probably, because the general hormonal situation changes in connection with the achievement of puberty: estrogens reduce the activity of growth hormone.

Thyroid stimulating hormone (TSH) regulates the activity of the thyroid gland in accordance with the needs of the body. The mechanism of the effect of TSH on the thyroid gland is still not fully understood, but its administration increases the mass of the organ and increases the secretion of thyroid hormones. The action of TSH on protein, fat, carbohydrate, mineral and water metabolism is carried out through thyroid hormones.

TSH-producing cells appear in 8-week-old embryos. During the entire intrauterine period, the absolute content of TSH in the pituitary gland increases and in a 4-month-old fetus it is 3-5 times higher than in adults. This level is maintained until birth. TSH begins to affect the thyroid gland of the fetus from the second third of pregnancy. however, the dependence of thyroid function on TSH in the fetus is less pronounced than in adults. The connection between the hypothalamus and the pituitary gland is established only in the last months of fetal development.

In the first year of a child's life, the concentration of TSH in the pituitary gland increases. A significant increase in synthesis and secretion is observed twice: immediately after birth and in the period preceding puberty (prepubertal). The first increase in TSH secretion is associated with the adaptation of newborns to living conditions, the second corresponds to hormonal changes, including an increase in the function of the gonads. The maximum secretion of the hormone is reached at the age of 21 to 30 years, at 51-85 years its value is halved.

Adrenocorticotropic hormone (ACTH) acts indirectly on the body, stimulating the secretion of adrenal hormones. In addition, ACTH has direct melanocyte-stimulating and lipolytic activity, therefore, an increase or decrease in ACTH secretion in children is accompanied by complex dysfunctions of many organs and systems.

With increased secretion of ACTH (Itsenko-Cushing's disease), growth retardation, obesity (deposition of fat mainly on the trunk), moon-shaped face, premature development of pubic hair, osteoporosis, hypertension, diabetes, trophic skin disorders (stretch bands) are observed. With insufficient secretion of ACTH, changes characteristic of a lack of glucocorticoids are detected.

In the intrauterine period, the secretion of ACTH in the embryo begins from the 9th week, and on the 7th month its content in the pituitary gland reaches a high level. During this period, the fetal adrenal glands respond to ACTH - they increase the rate of formation of godrocortisone and testosterone. In the second half of intrauterine development, not only direct, but also feedback between the pituitary and adrenal glands of the fetus begin to operate. In newborns, all links of the hypothalamus-pituitary-adrenal cortex system function. From the first hours after birth, children already respond to stressful stimuli (associated, for example, with protracted labor, surgical interventions, etc.) an increase in the content of corticosteroids in the urine. These reactions, however, are less pronounced than in adults, due to the low sensitivity of the hypotadamic structures to changes in the internal and external environment of the body. The influence of the nuclei of the hypothalamus on the function of the adenohypophysis is enhanced. that under stress is accompanied by an increase in the secretion of ACTH. In old age, the sensitivity of the nuclei of the hypothalamus again falls, which is the reason for the lower severity of the adaptation syndrome in old age.

Gonadotropic (gonadotropins) are called follicle-stimulating and luteinizing hormones

Follicle-stimulating hormone (FSH) in the female body causes the growth of ovarian follicles, promotes the formation of estrogen in them. In the male body, it affects spermatogenesis in the testes. FSH release depends on pata and age

Luteinizing hormone (LH) causes ovulation, promotes the formation of the corpus luteum in the ovaries of the female body, and in the male body stimulates the growth of seminal vesicles and the prostate gland, as well as the production of androgens in the testes.

Cells that produce FSH and LH develop in the pituitary gland by the 8th week of intrauterine development, at the same time LH appears in them. and at week 10 - FSH. In the blood of the embryo, gonadotropins appear from the age of 3 months. In the blood of female fetuses, especially in the last third of fetal development, their concentration is higher than in males. The maximum concentration of both hormones falls on the period of 4.5–6.5 months of the prenatal period. The significance of this fact has not yet been fully elucidated.

Gonadotropic hormones stimulate the endocrine secretion of the gonads of the fetus, but do not control their sexual differentiation. In the second half of the prenatal period, a connection is formed between the hypothalamus, the gonadotropic function of the pituitary gland and the hormones of the gonads. This occurs after the differentiation of the sex of the fetus under the influence of testosterone.

In newborns, the concentration of LH in the blood is very high, but during the first week after birth it decreases and remains low until the age of 7–8 years. In the pubertal period, the secretion of gonadotropins increases, by the age of 14 it increases by 2-2.5 times. In girls, gonadotropic hormones cause the growth and development of the ovaries, there is a cyclical secretion of FSH and LH, which is the reason for the onset of new sexual cycles. By the age of 18, FSH and LH levels reach adult values.

Prolactin, or luteotropic hormone (LTP. Stimulates the function of the corpus luteum and promotes lactation, i.e. the formation and secretion of milk. The regulation of hormone formation is carried out by the prolactin-inhibiting factor of the hypothalamus, estrogens and thyrotropin-releasing hormone (TRH) of the hypothalamus. The last two hormones have a stimulating effect on the secretion of the hormone An increase in the concentration of prolactin leads to an increase in the release of dopamine by the cells of the hypothalamus, which inhibits the secretion of the hormone.This mechanism works during the absence of lactation, an excess of dopamine inhibits the activity of cells that form prolactin.

The secretion of prolactin begins from the 4th month of intrauterine development and increases significantly in the last months of pregnancy. It is believed that he is also involved in the regulation of metabolism in the fetus. At the end of pregnancy, prolactin levels become high both in the mother's blood and in the amniotic fluid. In newborns, the concentration of prolactin in the blood is high. It decreases during the first year of life. and increases during puberty. and stronger in girls than in boys. In adolescent boys, prolactin stimulates the growth of the prostate and seminal vesicles.

The middle lobe of the pituitary gland influences the hormone formation processes of the adenohypophysis. It is involved in the secretion of melanostimulating hormone (MSH) (melanotropin) and ACTH. MSH is important for skin and hair pigmentation. In the blood of pregnant women, its content is increased, in connection with which pigment spots appear on the skin. In fetuses, the hormone begins to be synthesized at the 10-11th week. but its function in development is still not entirely clear.

The posterior lobe of the pituitary gland, together with the hypothalamus, functionally constitutes a single whole Hormones synthesized in the nuclei of the hypothalamus - vasopressin and oxytocin - are transported to the posterior lobe of the pituitary gland and stored here until released into the blood

Vasopressin, or antidiuretic hormone (ADH). The target organ of ADH is the kidney. The epithelium of the collecting ducts of the kidneys becomes permeable to water only under the action of ADH. which provides passive reabsorption of water. Under conditions of increased salt concentration in the blood, the concentration of ADH increases and, as a result, the urine becomes more concentrated, and water loss is minimal. With a decrease in the concentration of salts in the blood, the secretion of ADH decreases. Drinking alcohol further reduces ADH secretion, which explains the significant diuresis after drinking fluids along with alcohol.

With the introduction of large amounts of ADH into the blood, narrowing of the arteries is clearly expressed due to the stimulation of the smooth muscles of the vessels by this hormone, resulting in an increase in blood pressure (the vasopressor effect of the hormone). A sharp drop in blood pressure during blood loss or shock dramatically increases the secretion of ADH. As a result, blood pressure rises. A disease that occurs when there is a violation of the secretion of ADH. called diabetes insipidus. This produces a large amount of urine with a normal sugar content in it.

The antidiuretic hormone of the pituitary gland begins to be released at the 4th month of embryonic development, its maximum release occurs at the end of the first year of life, then the antidiuretic activity of the neurohypophysis begins to fall to rather low values, and at the age of 55 it is approximately 2 times less than in a one-year-old child .

The target organ for oxytocin is the muscular layer of the uterus and myoepithelial cells of the mammary gland. Under physiological conditions, the mammary glands begin to secrete milk on the first day after childbirth, and at this time the baby can already suckle. The act of sucking serves as a strong stimulus for the tactile receptors on the nipple. From these receptors, along the nerve pathways, impulses are transmitted to the neurons of the hypothalamus, which are also secretory cells that produce oxytocin. The latter is transferred with blood to the myoepithelial cells. lining the mammary gland. Myoepithelial cells are located around the alveoli of the gland, and during contraction, milk is squeezed out into the ducts. Thus, to extract milk from the gland, the infant does not require active sucking, since it is assisted by the “milk release” reflex.

The activation of labor is also associated with oxytocin. With mechanical stimulation of the birth canal, nerve impulses that enter the neurosecretory cells of the hypothalamus cause the release of oxytocin into the blood. By the end of pregnancy, under the influence of female sex hormones estrogens, the sensitivity of the uterus muscles (myometrium) to oxytocin sharply increases. At the beginning of labor, the secretion of oxytocin increases, which causes weak contractions of the uterus, which pushes the fetus towards the cervix and vagina. The stretching of these tissues causes the excitation of numerous mechanoreceptors in them. From which the signal is transmitted to the hypothalamus. Neurosecretory labels of the hypothalamus respond by releasing new portions of oxytocin, due to which uterine contractions increase. This process eventually progresses into childbirth, during which the fetus and placenta are expelled. After the expulsion of the fetus, the stimulation of mechanoreceptors and the release of oxytocin cease.

The synthesis of hormones of the posterior pituitary gland begins in the nuclei of the hypothalamus at the 3-4th month of the prenatal period, and at the 4-5th month they are found in the pituitary gland. The content of these hormones in the pituitary gland and their concentration in the blood gradually increase by the time the child is born. In children of the first months of life, the antidiuretic effect of vasopressin does not play a significant role, only with age its importance in water retention in the body increases. In children, only the antidiuretic effect of oxytocin is manifested, its other functions are poorly expressed. The uterus and mammary glands begin to respond to oxytocin only after the completion of puberty, that is, after prolonged action of the sex hormones estrogens and progesterone on the uterus, and the pituitary hormone prolactin on the mammary gland.