The human endocrine system is an important department, with pathologies of which there is a change in speed and nature. metabolic processes, the sensitivity of tissues decreases, the secretion and transformation of hormones is disturbed. Against the background of hormonal disruptions, sexual and reproductive function, appearance changes, working capacity, well-being worsens.

Every year, endocrine pathologies are increasingly detected by physicians in young patients and children. The combination of environmental, industrial and other adverse factors with stress, overwork, hereditary predisposition increases the likelihood of chronic pathologies. It is important to know how to avoid the development of metabolic disorders, hormonal disruptions.

general information

The main elements are located in different parts of the body. - a special gland, in which not only the secretion of hormones occurs, but also the process of interaction between the endocrine and nervous systems for the optimal regulation of functions in all parts of the body.

The endocrine system ensures the transfer of information between cells and tissues, the regulation of the functioning of departments with the help of specific substances - hormones. Glands produce regulators with a certain frequency, in optimal concentration. The synthesis of hormones weakens or increases against the background of natural processes, for example, pregnancy, aging, ovulation, menstruation, lactation, or during pathological changes different nature.

Endocrine glands are formations and structures different size, producing a specific secret directly into the lymph, blood, cerebrospinal, intercellular fluid. Absence of external ducts, as in the salivary glands - specific feature, on the basis of which, the hypothalamus, thyroid gland, pineal gland are called endocrine glands.

Classification of the endocrine glands:

• central and peripheral. The separation is carried out by the connection of the elements with the central nervous system. Peripheral parts: sex glands, thyroid gland, pancreas. Central glands: epiphysis, pituitary gland, hypothalamus - parts of the brain;
• pituitary independent and hypophysis dependent. The classification is based on the influence of the tropic hormones of the pituitary gland on the work of the elements of the endocrine system.

The structure of the endocrine system

The complex structure provides a diverse effect on organs and tissues. The system consists of several elements that regulate the functioning of a particular department of the body or several physiological processes.

The main divisions of the endocrine system:

• diffuse system- glandular cells that produce substances that act like hormones;
• local system- classic glands that produce hormones;
• specific substance capture system- amine precursors and subsequent decarboxylation. Components - glandular cells producing biogenic amines and peptides.

Organs of the endocrine system (endocrine glands):

• adrenal glands;
• pituitary;
• hypothalamus;
• epiphysis;

Organs containing endocrine tissue:

• testes, ovaries;
• pancreas.

Organs containing endocrine cells:

• thymus;
• kidneys;
• organs of the gastrointestinal tract;
• central nervous system (the main role belongs to the hypothalamus);
• placenta;
• lungs;
• prostate.

The body regulates the functions of the endocrine glands in several ways:

• first. Direct influence on gland tissues with the help of a specific component, for the level of which a certain hormone is responsible. For example, values ​​decrease when increased secretion occurs in response to an increase in concentration. Another example is the suppression of secretion with an excess concentration of calcium acting on the cells of the parathyroid glands. If the concentration of Ca falls, then the production of parathyroid hormone, on the contrary, increases;
• second. The hypothalamus and neurohormones carry out the nervous regulation of the functions of the endocrine system. In most cases, nerve fibers affect the blood supply, the tone of the blood vessels of the hypothalamus.

On a note! Influenced by external and internal factors both a decrease in the activity of the endocrine gland (hypofunction) and an increased synthesis of hormones (hyperfunction) are possible.

Hormones: properties and functions

According to the chemical structure, hormones are:

• steroid. The lipid base, substances actively penetrate through cell membranes, prolonged exposure, provoke a change in the processes of translation and transcription during the synthesis of protein compounds. Sex hormones, corticosteroids, vitamin D sterols;
• derivatives of amino acids. The main groups and types of regulators: thyroid hormones (and), catecholamines (norepinephrine and adrenaline, which are often called "stress hormones"), a tryptophan derivative - a histidine derivative - histamine;
• protein-peptide. The composition of hormones is from 5 to 20 amino acid residues in peptides and more than 20 in protein compounds. Glycoproteins (and), polypeptides (vasopressin and glucagon), simple protein compounds (somatotropin, insulin). Protein and peptide hormones are a large group of regulators. It also includes ACTH, STH, LTH, (pituitary hormones), thyrocalcitonin (thyroid), (pineal gland hormone), parathyroid hormone (parathyroid glands).

Derivatives of amino acids and steroid hormones exhibit the same type of action, peptide and protein regulators have a pronounced species specificity. Among the regulators there are peptides of sleep, learning and memory, drinking and eating behavior, analgesics, neurotransmitters, regulators of muscle tone, mood, sexual behavior. This category includes immune, survival and growth stimulants,

Peptides-regulators often affect the organs not independently, but in combination with bioactive substances, hormones and mediators, they show a local effect. Feature- synthesis in various departments organism: gastrointestinal tract, central nervous system, heart, reproductive system.

The target organ has receptors for a particular type of hormone. For example, the bones are susceptible to the action of the regulators of the parathyroid glands, small intestine, kidneys.

The main properties of hormones:

• specificity;
• high biological activity;
• distance of influence;
• secretion.

The lack of one of the hormones cannot be compensated with the help of another regulator. In the absence of a specific substance, excessive secretion or low concentration, a pathological process develops.

Diagnosis of diseases

To assess the functionality of the glands that produce regulators, several types of studies of various levels of complexity are used. First, the doctor examines the patient and the problem area, for example, the thyroid gland, identifies external signs deviations and .

Be sure to take a personal/family history: many endocrine diseases have a hereditary predisposition. The following is a set of diagnostic measures. Only a series of tests in combination with instrumental diagnostics makes it possible to understand what type of pathology is developing.

The main methods for studying the endocrine system:

• identification of symptoms characteristic of pathologies against the background of hormonal disruptions and abnormal metabolism;
• radioimmunoassay;
• holding a problem organ;
• orchiometry;
• densitometry;
• immunoradiometric analysis;
• test for ;
• conducting and CT;
• the introduction of concentrated extracts of certain glands;
• Genetic Engineering;
• radioisotope scanning, application of radioisotopes;
• determination of the level of hormones, metabolic products of regulators in various types of fluid (blood, urine, cerebrospinal fluid);
• study of receptor activity in target organs and tissues;
• clarification of the size of the problematic gland, assessment of the growth dynamics of the affected organ;
• accounting for circadian rhythms in the production of certain hormones in combination with the age and gender of the patient;
• conducting tests with artificial suppression of the activity of the endocrine organ;
• comparison of blood parameters entering and exiting the gland under study

On the page, read the instructions for using Mastodinon drops and tablets for the treatment of mastopathy of the mammary glands.

Endocrine pathologies, causes and symptoms

Diseases of the pituitary gland, thyroid gland, hypothalamus, pineal gland, pancreas, and other elements:

• endocrine hypertension;
• pituitary dwarfism;
• , endemic and ;

The endocrine system occupies a special place among the internal structures of a person. This is due to the fact that its activity extends to all organs and tissues.

General information

A certain number of cells of the endocrine system are collected together. They form the glandular apparatus - intrasecretory glands. The compounds that the structure produces penetrate directly into the cells through the intercellular substance or are carried with the blood. The science that carries out the general study of structure is biology. The endocrine system has great value for a person and performs the most important functions in ensuring normal life.

Structure functions

The organism takes part in chemical processes, coordinates the activities of all organs and other structures. It is responsible for the stable course of life processes in conditions constant change external environment. Like the immune and nervous systems, the endocrine system is involved in the control of human development and growth, the functioning of the reproductive organs, and sexual differentiation. Its activities also extend to the formation emotional reactions, mental behavior. The endocrine system is, among other things, one of the generators of human energy.

The constituent elements of the structure

The endocrine system of the body includes intrasecretory elements. In their totality, they constitute the glandular apparatus. It produces some hormones of the endocrine system. In addition, almost every structure cells are present. A group of endocrine cells scattered throughout the body forms the diffuse part of the system.

Intrasecretory elements

The glandular apparatus includes the following intrasecretory systems:

diffuse part

The main element that includes the endocrine system in this case is pituitary. This gland of the diffuse part of the structure is of particular importance. It can be called the central body. The pituitary gland closely interacts with the hypothalamus, forming the pituitary-hypothalamic apparatus. Thanks to him, the regulation of the interaction of compounds produced by the pineal gland is carried out.

The central organ produces compounds that stimulate and regulate the endocrine system. The anterior pituitary gland produces six essential substances. They are called dominant. These include, in particular, adrenocorticotropic hormone, thyrotropin, four gonadotropic compounds that control the activity of the sexual elements of the structure. Somatropin is also produced here. This is a very important connection for a person. Somatropin is also called growth hormone. It is the main factor influencing the development of the bone, muscle and cartilage apparatus. With excessive production of somatropin in adults, agrokemalia is diagnosed. This pathology is manifested in an increase in the bones of the face and limbs.

epiphysis

It produces the regulation of water balance in the body, as well as oxytocin. The latter is responsible for the contractility of smooth muscles (including the uterus during childbirth). In the epiphysis, hormonal compounds are produced. These include norepinephrine and melatonin. The latter is a hormone responsible for the sequence of phases during sleep. With the participation of norepinephrine, the regulation of the nervous and endocrine systems, as well as blood circulation, is carried out. All components of the structure are interconnected. When any element falls out, the regulation of the endocrine system is disturbed, as a result of which failures occur in other structures.

General information about pathologies

Systems are expressed in states associated with hyper-, hypo- or dysfunction of the intrasecretory glands. Currently, medicine knows a lot of different therapeutic methods able to adjust the activity of the structure. Influence the choice of adequate options that correct the functions that the endocrine system has, symptoms, type and stage of pathology, individual characteristics patient. As a rule, complex therapy is used for major diseases. This choice is due to the fact that the endocrine system is a rather complex structure, and the use of any one option to eliminate the causes of failure is not enough.

Steroid therapy

As mentioned above, the endocrine system is a structure whose elements produce chemical compounds involved in the activities of other organs and tissues. In this regard, the main method of eliminating certain failures in the production of substances is steroid therapy. It is applied, in particular, when an insufficient or excessive content of compounds produced by the endocrine system is diagnosed. Treatment with steroids without fail appointed after a series of operations. Therapy, as a rule, involves a special scheme for taking drugs. After partial or complete removal glands, for example, the patient is prescribed a lifelong intake of hormones.

Other drugs

For many pathologies that affect the endocrine system, treatment involves taking general tonic, anti-inflammatory, antibiotic agents. Radioactive iodine therapy is also often used. At cancer pathologies radioactive irradiation is used to destroy pathologically dangerous and damaged cells.

The list of medicines used to normalize the endocrine system

At the heart of many medicines there are natural ingredients. Such agents are more preferable in the treatment of a number of diseases. The activity of the active substances of such drugs is aimed at stimulating metabolic processes and normalizing the hormonal background. Specialists distinguish especially the following drugs:

• "Omega Q10". This remedy strengthens the immune system and normalizes the functions of the endocrine glands.
• "Flavit-L". This drug is designed to treat and prevent disorders of the endocrine system in women.
• "Detovit". This tool is quite powerful and is used for chronic disorders functioning of the intrasecretory glands.
• "Apollo-IVA". This remedy has the ability to stimulate the immune and endocrine systems.

Surgery

Surgical methods are considered the most effective in the treatment of endocrine pathologies. However, they are used as a last resort if possible. One of the direct indications for the appointment of surgical intervention is a tumor that threatens a person's life. Given the severity of the pathology, part of the gland or the organ can be removed completely. At cancerous tumors tissues near the foci are also subject to removal.

Alternative methods of treatment of diseases of the endocrine system

Because of a large number of medicines presented today in the network of pharmacies, has a synthetic basis and has a number of contraindications, herbal treatment is becoming more and more popular. However, it should be noted that the use herbal remedies without expert advice can be dangerous. Among the most common recipes, we note a few. So, for hyperthyroidism, a herbal collection is used, which includes (4 parts), catnip grass (3 hours), oregano (3 hours), peppermint (leaves), motherwort (1 hour). Raw materials need to take two tablespoons. The collection is poured with boiling water (five hundred milliliters) and insisted overnight in a thermos. In the morning it is filtered. Take 1/2 cup before meals three times a day. Duration of admission - two months. After two or three months, the course is repeated.

Obese people are recommended decoctions and infusions that reduce appetite and increase the release of interstitial fluid from the body. Regardless of which one is chosen folk recipe, the funds should be used only after visiting the doctor.

It is difficult to overestimate the role of the hormonal regulatory system of the body - it controls the activity of all tissues and organs by activating or inhibiting the production of the corresponding hormones. Violation of the work of at least one of the endocrine glands entails consequences that are dangerous for human life and health. Early detection deviations will help to avoid complications that are difficult to treat and lead to a deterioration in the quality of life.

General information about the endocrine system

The humoral regulatory function in the human body is realized through the coordinated work of the endocrine and nervous systems. All tissues contain endocrine cells that produce biologically active substances capable of affecting target cells. The human hormonal system is represented by three types of hormones:

• secreted by the pituitary gland;
• produced by the endocrine system;
• produced by other organs.

A distinctive feature of the substances produced by the endocrine glands is that they enter directly into the blood. The hormonal system of regulation, depending on where the secretion of hormones occurs, is divided into diffuse and glandular:

Functions

The health and well-being of a person depends on how well all the organs and tissues of the body work, and how quickly the regulatory mechanism of adaptation to changes in exogenous or endogenous conditions of existence works. Creating an individual microclimate that is optimal for the specific conditions of an individual's life is the main task of the regulatory mechanism, which the endocrine system implements through:

Elements of the endocrine system

Implementation of synthesis and isolation in systemic circulation active biological substances produced by the endocrine system. Glandular bodies of internal secretion represent a concentration of endocrine cells and belong to HES. The regulation of the activity of production and release of hormones into the blood occurs through nerve impulses from the central nervous system (CNS) and peripheral cellular structures. The endocrine system is represented by the following main elements:

• derivatives of epithelial tissues;
• glands thyroid, parathyroid, pancreas;
• adrenal glands;
• gonads;
• epiphysis;
• thymus.

Thyroid and parathyroid glands

The production of iodothyronines (iodine-containing hormones) is carried out by the thyroid gland, located in the front of the neck. Functional value iodine in the body is reduced to the regulation of metabolism and the ability to absorb glucose. Transportation of iodine ions occurs with the help of transport proteins located in the membrane epithelium of thyroid cells.

The follicular structure of the gland is represented by a cluster of oval and round vesicles filled with a protein substance. Epithelial cells (thyrocytes) of the thyroid gland produce thyroid hormones - thyroxine, triiodothyronine. Parafollicular cells located on the basement membrane of thyrocytes produce calcitonin, which ensures the balance of phosphorus and potassium in the body, by increasing the uptake of calcium and phosphate by young cells. bone tissue(osteoblasts).

On the back of the bilobular surface of the thyroid gland, which weighs 20-30 g, there are four parathyroid glands. Nerve structures and the musculoskeletal system are regulated by hormones secreted by parathyroid glands. If the level of calcium in the body drops below the permissible norm, the protective mechanism of calcium-sensitive receptors is triggered, which activate the secretion of parathyroid hormone. Osteoclasts (cells that dissolve the mineral component of bones) under the influence of parathyroid hormone begin to release calcium from bone tissue into the blood.

pancreas

Between the spleen and the duodenum at the level of 1-2 lumbar vertebrae is a large secretory organ of dual action - the pancreas. The functions implemented by this organ are the secretion of pancreatic juice (external secretion) and the production of hormones (gastrin, cholecystokinin, secretin). As the main source digestive enzymes, the pancreas produces such vital important substances, how:

• trypsin - an enzyme that breaks down peptides and proteins;
• pancreatic lipase - breaks down triglycerides into glycerol and carboxylic acids, its function is to hydrolyze dietary fats;
• amylase - glycosyl hydrolase, converts polysaccharides into oligosaccharides.

The pancreas consists of lobules, between which there is an accumulation of secreted enzymes and their subsequent excretion into the duodenum. The interlobular ducts represent the excretory part of the organ, and the islets of Langerhans (an accumulation of endocrine cells without excretory ducts) represent the endocrine part. The function of the pancreatic islets is to maintain carbohydrate metabolism, in violation of which diabetes mellitus develops. Islet cells come in several types, each producing a specific hormone:

adrenal glands

Intercellular interaction in the human body is achieved through chemical mediators - catecholamine hormones. The main source of these biologically active substances are the adrenal glands located on the top of both kidneys. Paired endocrine glandular bodies consist of two layers - cortical (external) and cerebral (internal). The regulation of the hormonal activity of the external structure is carried out by the central nervous system, the internal - by the peripheral nervous system.

The cortical layer is a supplier of steroids that regulate metabolic processes. The morphological and functional structure of the adrenal cortex is represented by three zones in which the following hormones are synthesized:

The inner layer of the adrenal glands is innervated by preganglionic fibers of the sympathetic nervous system. The cells of the medulla produce adrenaline, norepinephrine and peptides. The main functions of hormones produced by the inner layer of the adrenal glands are as follows:

• adrenaline - mobilization internal forces the body in case of danger (increased contractions of the heart muscle, increased pressure), catalyzing the process of converting glycogen into glucose by increasing the activity of glycolytic enzymes;
• norepinephrine - regulation of blood pressure when changing body position, synergizes with the action of adrenaline, supporting all the processes it has launched;
• substance P (pain substance) - activation of the synthesis of inflammatory mediators and their release, transmission of pain impulses to the central nervous system, stimulation of the production of digestive enzymes;
• vasoactive peptide - transmission of electrochemical impulses between neurons, stimulation of blood flow in the intestinal walls, inhibition of production of hydrochloric acid;
• somatostatin - suppression of the activity of serotonin, insulin, glucagon, gastrin.

thymus

The maturation and training of the immune response of cells that destroy pathogenic antigens (T-lymphocytes) occurs in the thymus gland (thymus). This organ is located in the upper region of the sternum at the level of the 4th costal cartilage and consists of two closely adjacent lobes. The function of cloning and preparation of T cells is achieved through the production of cytokines (lymphokines) and thymopoietins:

epiphysis

One of the most poorly understood glands of the human body is the pineal gland or pineal gland. According to its anatomical affiliation, the pineal gland belongs to the DES, and morphological features indicate that it is outside the physiological barrier separating the circulatory and central nervous systems. The epiphysis is fed by two arteries - the superior cerebellar and the posterior cerebral.

The activity of producing hormones in the pineal gland decreases as they grow older - in children this organ is significantly larger than in adults. Biologically active substances produced by the gland - melatonin, dimethyltryptamine, adrenoglomeruotropin, serotonin - affect the immune system. The mechanism of action of hormones produced by the pineal gland determines the functions of the pineal gland, of which the following are currently known:

• synchronization of cyclic changes in the intensity of biological processes associated with the change of dark and daylight hours and temperature environment;
• maintaining natural biorhythms (the alternation of sleep with wakefulness is achieved by blocking the synthesis of melanin from serotonin under the action of bright light);
• inhibition of the synthesis of somatotropin (growth hormone);
• blocking of cell division of neoplasms;
• control of puberty and the production of sex hormones.

Gonads

The endocrine glands that produce sex hormones are called gonads, which include the testes or testes (male gonads) and the ovaries (female gonads). The endocrine activity of the sex glands is manifested in the production of androgens and estrogens, the secretion of which is controlled by the hypothalamus. The appearance of secondary sexual characteristics in humans occurs after the maturation of sex hormones. The main functions of male and female gonads are:

General information about diseases of the endocrine system

The endocrine glands provide the vital activity of the whole organism, therefore, any violation of their functioning can lead to the development pathological processes posing a danger to human life. A disorder in the work of one or several glands at once can occur due to:

• genetic abnormalities;
• received injuries internal organs;
• start tumor process;
• lesions of the central nervous system;
• immunological disorders (destruction glandular tissue own cells)
• development of tissue resistance to hormones;
• production of defective biologically active substances that are not perceived by organs;
• reactions to the hormonal drugs taken.

Diseases of the endocrine system are studied and classified by the science of endocrinology. Depending on the area of ​​occurrence of deviations and the method of their manifestation (hypofunction, hyperfunction or dysfunction), diseases are divided into the following groups:

Symptoms of endocrine disorders

Diseases caused by dysfunctional disorders of the endocrine glands are diagnosed on the basis of characteristic symptoms. The primary diagnosis is necessarily confirmed by laboratory tests, on the basis of which the content of hormones in the blood is determined. Violation of the endocrine system manifests itself in signs that are distinguished by their diversity, which makes it difficult to establish the cause of complaints only on the basis of a patient survey. The main symptoms that should be the reason for contacting an endocrinologist are:

• a sharp change in body weight (weight loss or weight gain) without significant changes in the diet;
• emotional imbalance, characterized by frequent mood swings for no apparent reason;
• increased frequency of urge to urinate (increased amount of urine output);
• the appearance of a persistent feeling of thirst;
• physical or mental development in children, acceleration or delay of puberty, growth;
• distortion of the proportions of the face and figure;
• increased work of sweat glands;
• chronic fatigue, weakness, drowsiness;
• amenorrhea;
• changes in hair growth (excessive hair growth or alopecia);
• violation of intellectual abilities (memory impairment, decreased concentration of attention);
• decreased libido.

Treatment of the endocrine system

To eliminate the manifestations of impaired activity of the endocrine glands, it is necessary to identify the cause of the deviations. With diagnosed neoplasms, which resulted in diseases of the endocrine system, in most cases it is indicated surgical intervention. If comorbidities are not identified, a trial may be prescribed. diet food to regulate hormone production.

If the cause-forming factors of the violations were a decrease or excessive production of glandular secretion, drug treatment is used, which involves taking the following groups of drugs:

• steroid hormones;
• restorative means(affect the immune system);
• anti-inflammatory drugs;
• antibiotic agents;
• radioactive iodine;
• vitamin-containing complexes;
• homeopathic remedies.

Disease prevention

To minimize the risk of abnormalities in the work of the intrasecretory glands, the recommendations of endocrinologists should be followed. The main rules for the prevention of endocrine disorders are:

• timely access to a doctor if disturbing signs are detected;
• limiting the impact of aggressive environmental factors that have a negative impact on the body ( ultraviolet radiation, chemical substances);
• adherence to the principles of a balanced diet;
• rejection bad habits;
• treatment of infections and inflammatory diseases on the early stage;
• control of negative emotions;
• moderate physical activity;
• regular preventive diagnostics of hormone levels (sugar levels - annually, thyroid hormones - 1 time in 5 years).

Video

ORGANS OF THE ENDOCRINE SYSTEM

ORGANS OF THE ENDOCRINE SYSTEM

organs of the endocrine system, or endocrine glands, produce biologically active substances - hormones, which are released by them into the blood and, spreading with it throughout the body, affect the cells various bodies and fabrics (target cells), regulating their growth and activity due to the presence on these cells of specific hormone receptors.

Endocrine glands (such as, for example, the pituitary, pineal, adrenal, thyroid and parathyroid glands) are independent organs, but in addition to them, hormones are also produced by individual endocrine cells and their groups, which are scattered among non-endocrine tissues - such cells and their groups form dispersed (diffuse) endocrine system. A significant number of cells of the dispersed endocrine system are found in the mucous membranes of various organs, they are especially numerous in digestive tract, where their combination was called the gastro-entero-pancreatic (GEP) system.

The endocrine glands, which have an organ structure, are usually covered with a capsule of dense connective tissue, from which thinning trabeculae extend deep into the organ, consisting of loose fibrous connective tissue and carrying vessels and nerves. In most endocrine glands, the cells form cords and adhere closely to the capillaries, which ensures the secretion of hormones into the bloodstream. Unlike other endocrine glands, the cells in the thyroid gland do not form strands, but are organized into small vesicles called follicles. Capillaries in the endocrine glands form very dense networks and, due to their structure, have increased permeability - they are fenestrated or sinusoidal. Since hormones are secreted into the bloodstream and not onto the surface of the body or into the cavity of organs (as in exocrine glands), there are no excretory ducts in the endocrine glands.

Functionally leading (hormone-producing) tissue endocrine glands are traditionally considered epithelial (related to various histogenetic types). Indeed, the epithelium is the functionally leading tissue of most of the endocrine glands (thyroid and parathyroid glands, anterior and intermediate lobes of the pituitary gland, adrenal cortex). Some endocrine elements of the gonads also have an epithelial nature - ovarian follicular cells, testicular sustentocytes, etc.). but

at present, there is no doubt that all other types of tissues are also capable of producing hormones. In particular, hormones are produced by muscle tissue cells (smooth as part of the juxtaglomerular apparatus of the kidney - see Chapter 15 and striated, including secretory cardiomyocytes in the atria - see Chapter 9).

Some endocrine elements of the gonads have a connective tissue origin (for example, interstitial endocrinocytes - Leydig cells, cells of the inner layer of the theca of ovarian follicles, chyle cells of the ovarian medulla - see chapters 16 and 17). The neural origin is characteristic of neuroendocrine cells of the hypothalamus, cells pineal gland, neurohypophysis, adrenal medulla, some elements of the dispersed endocrine system (for example, C-cells of the thyroid gland - see below). Some endocrine glands (pituitary gland, adrenal gland) are formed by tissues of different embryonic origin and located separately in lower vertebrates.

The cells of the endocrine glands are characterized by high secretory activity and significant development of the synthetic apparatus; their structure depends primarily on the chemical nature of the hormones produced. In the cells that form peptide hormones, the granular endoplasmic reticulum, the Golgi complex, are strongly developed, in those synthesizing steroid hormones, the agranular endoplasmic reticulum, mitochondria with tubular-vesicular cristae. The accumulation of hormones usually occurs intracellularly in the form of secretory granules; hypothalamic neurohormones can accumulate in large quantities inside axons, sharply stretching them in separate areas (neurosecretory bodies). The only example of extracellular accumulation of hormones is in the follicles of the thyroid gland.

The organs of the endocrine system belong to several levels of organization. The lower one is occupied by glands that produce hormones that affect various tissues of the body. (effector, or peripheral, glands). The activity of most of these glands is regulated by special tropic hormones of the anterior lobe. pituitary gland(second, higher level). In turn, the release of tropic hormones is controlled by special neurohormones. hypothalamus, which occupies the highest position in the hierarchical organization of the system.

Hypothalamus

Hypothalamus- area of ​​the diencephalon containing special neurosecretory nuclei, whose cells (neuroendocrine cells) produced and secreted into the blood neurohormones. These cells receive efferent impulses from other parts of the nervous system, and their axons terminate on blood vessels. (neurovascular synapses). Neurosecretory nuclei of the hypothalamus, depending on the size of the cells and their functional features divided into large- and small cell.

Large cell nuclei of the hypothalamus formed by the bodies of neuroendocrine cells, the axons of which leave the hypothalamus, forming the hypothalamic-pituitary tract, cross the blood-brain barrier, penetrate into the posterior lobe of the pituitary gland, where they form capillary terminals (Fig. 165). These cores are supraoptic and paraventricular, which secrete antidiuretic hormone, or vasopressin(increases blood pressure, provides reverse absorption of water in the kidneys) and oxytocin(causes contractions of the uterus during childbirth, as well as myoepithelial cells of the mammary gland during lactation).

Small cell nuclei of the hypothalamus produce a number of hypophysiotropic factors that enhance (releasing factors, or liberins) or oppress (inhibiting factors, or statins) the production of hormones by the cells of the anterior lobe, getting to them through portal vascular system. The axons of the neuroendocrine cells of these nuclei form terminals on primary capillary network v middle elevation, which is the neurohemal contact zone. This network is further collected in the portal veins, penetrating the anterior pituitary gland and breaking up into secondary capillary network between strands of endocrinocytes (see Fig. 165).

hypothalamic neuroendocrine cells- process form, with a large vesicular nucleus, a clearly visible nucleolus and basophilic cytoplasm containing a developed granular endoplasmic reticulum and large complex Golgi, from which neurosecretory granules are separated (Fig. 166 and 167). Granules are transported along the axon (neurosecretory fiber) along the central bundle of microtubules and microfilaments, and in some places they accumulate in large quantities, stretching the axon varicosely - preterminal and axon terminal extensions. The largest of these areas are clearly visible under a light microscope and are called neurosecretory bodies(Gerring). Terminals (neurohemal synapses) are characterized by the presence, in addition to granules, of numerous light vesicles (they return the membrane after exocytosis).

Pituitary

Pituitary regulates the activity of a number of endocrine glands and serves as a site for the release of hypothalamic hormones of the large cell nuclei of the hypothalamus. Interacting with the hypothalamus, the pituitary gland forms with it a single hypothalamic-pituitary neurosecretory system. The pituitary gland consists of two embryologically, structurally and functionally various parts - neural (posterior) lobe - part of the outgrowth of the diencephalon (neurohypophysis) and adenohypophysis, the leading tissue of which is the epithelium. The adenohypophysis divides into a larger anterior lobe (distal part), narrow intermediate part (share) and underdeveloped tubular part.

The pituitary gland is covered with a capsule of dense fibrous connective tissue. Its stroma is represented by very thin layers of loose connective tissue associated with a network of reticular fibers, which in the adenohypophysis surrounds strands of epithelial cells and small vessels.

Anterior lobe (distal) pituitary gland and in humans it makes up most of its mass; it is formed by anastomosing trabeculae, or strands, endocrine cells, closely related to the sinusoidal capillary system. Based on the characteristics of the color of their cytoplasm, they distinguish: 1) chromophilic(intensely colored) and 2) chromophobic(weakly perceiving dyes) cells (endocrinocytes).

Chromophilic cells depending on the color of the secretory granules containing hormones, they are divided into acidophilic and basophilic endocrinocytes(Fig. 168).

acidophilic endocrinocytes develop somatotropic hormone, or growth hormone, which stimulates growth and prolactin or lactotropic hormone, which stimulates the development of mammary glands and lactation.

Basophilic endocrinocytes include gonadotropic, thyrotropic and corticotropic cells, which produce respectively: follicle-stimulating hormone(FSH) and luteinizing hormone(LH) - regulate gametogenesis and the production of sex hormones in both sexes, thyrotropic hormone- enhances the activity of thyrocytes, adrenocorticotropic hormone- stimulates the activity of the adrenal cortex.

Chromophobic cells - a heterogeneous group of cells, which includes chromophilic cells after excretion of secretory granules, poorly differentiated cambial elements that can turn into basophils or acidophils.

Intermediate pituitary gland in humans, it is very poorly developed and consists of narrow discontinuous strands of basophilic and chromophobic cells that surround a series of cystic cavities (follicles), containing colloid(non-hormonal substance). Most of the cells secrete melanocyte-stimulating hormone(regulates the activity of melanocytes), some have the characteristics of corticotropes.

Posterior (neural) lobe contains: shoots (neurosecretory fibers) and terminals of neurosecretory cells of large-cell nuclei of the hypothalamus, through which vasopressin and oxytocin are transported and released into the blood; expanded areas along the processes and in the terminal area - neurosecretory bodies(Gerring); numerous fenestrated capillaries; pituicytes- process glial cells that perform supporting, trophic and regulatory function(Fig. 169).

Thyroid

Thyroid- the largest of the endocrine glands of the body - is formed by two shares, connected by an isthmus. Each share is covered capsule from dense fibrous connective tissue, from which layers (partitions) extend into the organ, carrying vessels and nerves (Fig. 170).

Follicles - morphofunctional units of the gland - closed formations of a rounded shape, the wall of which consists of a single layer of epithelial follicular cells (thyrocytes), the lumen contains their secretory product - a colloid (see Fig. 170 and 171). Follicular cells produce iodine-containing thyroid hormones (thyroxine, triiodothyronine), which regulate the activity of metabolic reactions and developmental processes. These hormones bind to the protein matrix and thyroglobulin stored within the follicles. Follicular cells are characterized by large light nuclei with a clearly visible nucleolus, numerous dilated cisterns of the granular endoplasmic reticulum and a large Golgi complex, and multiple microvilli are located on the apical surface (see Fig. 4 and 172). The shape of the follicular cells can vary from flat to columnar depending on functional state. Each follicle is surrounded perifollicular capillary network. Between the follicles are narrow layers of loose fibrous connective tissue (stroma of the gland) and compact islands interfollicular epithelium(see Fig. 170 and 171), which probably serves as a source

no formation of new follicles, however, it has been established that follicles can be formed by dividing existing ones.

C cells (parafollicular cells) have a neural origin and produce a protein hormone calcitonin, having a hypocalcemic effect. They are detected only by special staining methods and most often lie singly or in small groups parafollicular - in the wall of the follicle between thyrocytes and the basement membrane (see Fig. 172). Calcitonin accumulates in C-cells in dense granules and is excreted from the cells by the mechanism of exocytosis with an increase in the level of calcium in the blood.

Parathyroid glands

Parathyroid glands produce a polypeptide parathyroid hormone (parathormone), which is involved in the regulation of calcium metabolism, increasing the level of calcium in the blood. Each gland is covered with a thin capsule from dense connective tissue, from which partitions depart, dividing it into slices. The lobules are made up of strands of glandular cells. parathyrocytes, between which are thin layers of connective tissue with a network of fenestrated capillaries containing fat cells, the number of which increases significantly with age (Fig. 173 and 174).

Parathyrocytes divided into two main types - main and oxyphilic(see fig. 174).

Major parathyroid cells form the main part of the parenchyma of the organ. These are small, polygonal cells with weakly oxyphilic cytoplasm. Available in two versions (light and dark main parathyroid cells), reflecting low and high functional activity, respectively.

Oxyphilic parathyrocytes larger than the main ones, their cytoplasm is intensely stained with acidic dyes and is distinguished by a very high content of large mitochondria with a weak development of other organelles and the absence of secretory granules. In children, these cells are single, with age their number increases.

adrenal glands

adrenal glands- endocrine glands, which consist of two parts - cortical and medulla, with different origin, structure and function. Each adrenal gland is covered with a thick capsule from dense connective tissue, from which thin trabeculae extend into the cortical substance, carrying vessels and nerves.

Cortex (bark) of the adrenal gland develops from coelomic epithelium. It takes

most of the volume of the organ and is formed by three unsharply demarcated concentric layers (zones):(1) glomerular area,(2) beam zone and (3) mesh zone(Fig. 175). Cells of the adrenal cortex (corticosterocytes) develop corticosteroids- a group of steroid hormones that are synthesized from cholesterol.

Glomerular zone - thin outer, adjacent to the capsule; formed by columnar cells with a uniformly stained cytoplasm, which form rounded arches ("glomeruli"). The cells in this zone secrete mineralcorticoids- hormones that affect the content of electrolytes in the blood and blood pressure (in humans, the most important of them aldosterone).

beam zone - medium, forms the bulk of the crust; consists of large oxyphilic vacuolated cells - spongy corticosterocytes(spongiocytes), which form radially oriented strands ("bundles"), separated by sinusoidal capillaries. They are characterized by a very high content of lipid drops (more than in the cells of the glomerular and fascicular zones), mitochondria with tubular cristae, a powerful development of the agranular endoplasmic reticulum and the Golgi complex (Fig. 176). These cells produce glucocorticoids- hormones that pronounced action on various types of metabolism (especially carbohydrate) and on the immune system (the main one in humans is cortisol).

mesh zone - narrow internal, adjacent to the medulla - represented by anastomosing epithelial strands going into various directions(forming a "network"), between which there are blood vessels

pillars. The cells of this zone are smaller than in the beam zone; numerous lysosomes and lipofuscin granules are found in their cytoplasm. They work out sex steroids(the main ones in humans are dehydroepiandrosterone and its sulfate - have a weak androgenic effect).

Adrenal medulla has a neural origin - it is formed during embryogenesis by cells migrating from the neural crest. Its composition includes chromaffin, ganglionic and supporting cells.

Chromaffin cells of the medulla located in the form of nests and strands, have a polygonal shape, a large nucleus, fine-grained or vacuolated cytoplasm. They contain small mitochondria, rows of cisterns of the granular endoplasmic reticulum, a large Golgi complex, and numerous secretory granules. Synthesize catecholamines - adrenaline and norepinephrine - and are divided into two types:

1)adrenalocytes (light chromaffin cells)- numerically predominate, produce adrenaline, which accumulates in granules with a moderately dense matrix;

2)noradrenalocytes (dark chromaffin cells)- produce norepinephrine, which accumulates in granules with a matrix compacted in the center and light on the periphery. Secretory granules in both types of cells contain, in addition to catecholamines, proteins, including chromogranins (osmotic stabilizers), enkephalins, lipids, and ATP.

ganglion cells - are contained in a small number and represent multipolar autonomic neurons.

ORGANS OF THE ENDOCRINE SYSTEM

Rice. 165. Scheme of the structure of the hypothalamic-pituitary neurosecretory system

1 - large-cell neurosecretory nuclei of the hypothalamus, containing bodies of neuroendocrine cells: 1.1 - supraoptic, 1.2 - paraventricular; 2 - hypothalamic-pituitary neurosecretory tract, formed by axons of neuroendocrine cells with varicose veins(2.1), which terminate in neurovascular (neurohemal) synapses (2.2) on capillaries (3) in the posterior pituitary gland; 4 - blood-brain barrier; 5 - small cell neurosecretory nuclei of the hypothalamus, containing bodies of neuroendocrine cells, the axons of which (5.1) terminate in neurohemal synapses (5.2) on the capillaries of the primary network (6) formed by the superior pituitary artery (7); 8 - portal veins of the pituitary gland; 9 - secondary network of sinusoidal capillaries in the anterior pituitary gland; 10 - lower pituitary artery; 11 - pituitary veins; 12 - cavernous sinus

Large cell neurosecretory nuclei of the hypothalamus produce oxytocin and vasopressin, small cell nuclei produce liberins and statins.

Rice. 166. Neuroendocrine cells of the supraoptic nucleus of the hypothalamus

1 - neuroendocrine cells in different phases secretory cycle: 1.1 - perinuclear accumulation of neurosecretion; 2 - processes of neuroendocrine cells (neurosecretory fibers) with granules of neurosecretion; 3 - neurosecretory little body (Gerring) - varicose expansion of the axon of a neuroendocrine cell; 4 - nuclei of gliocytes; 5 - blood capillary

Rice. 167. Scheme of ultrastructural organization of hypothalamic neuroendocrine cells:

1 - perikaryon: 1.1 - nucleus, 1.2 - tanks of the granular endoplasmic reticulum, 1.3 - Golgi complex, 1.4 - neurosecretory granules; 2 - beginning of dendrites; 3 - axon with varicose extensions; 4 - neurosecretory little bodies (Gerring); 5 - neurovascular (neurohemal) synapse; 6 - blood capillary

Rice. 168. Pituitary. Plot of the anterior lobe

Stain: hematoxylin-eosin

1 - chromophobic endocrinocyte; 2 - acidophilic endocrinocyte; 3 - basophilic endocrinocyte; 4 - sinusoidal capillary

Rice. 169. Pituitary. Plot of the neural (posterior) lobe

Staining: paraldehyde magenta and azan according to Heidenhain

1 - neurosecretory fibers; 2 - neurosecretory bodies (Gerring); 3 - pituitite core; 4 - fenestrated blood capillary

Rice. 170. Thyroid gland (general view)

Stain: hematoxylin-eosin

1 - fibrous capsule; 2 - connective tissue stroma: 2.1 - blood vessel; 3 - follicles; 4 - interfollicular islets

Rice. 171. Thyroid gland (section)

Stain: hematoxylin-eosin

1 - follicle: 1.1 - follicular cell, 1.2 - basement membrane, 1.3 - colloid, 1.3.1 - resorption vacuoles; 2 - interfollicular islet; 3- connective tissue(stroma): 3.1 - blood vessel

Rice. 172. Ultrastructural organization of follicular cells and C-cells of the thyroid gland

Drawing with EMF

1 - follicular cell: 1.1 - tanks of the granular endoplasmic reticulum, 1.2 - microvilli;

2- colloid in the lumen of the follicle; 3 - C-cell (parafollicular): 3.1 - secretory granules; 4 - basement membrane; 5 - blood capillary

Rice. 173. Parathyroid(general form)

Stain: hematoxylin-eosin

1 - capsule; 2 - strands of parathyrocytes; 3 - connective tissue (stroma): 3.1 - adipocytes; 4 - blood vessels

Rice. 174. Parathyroid gland (section)

Stain: hematoxylin-eosin

1 - main parathyrocytes; 2 - oxyphilic parathyrocyte; 3 - stroma: 3.1 - adipocytes; 4 - blood capillary

Rice. 175. Adrenal gland

Stain: hematoxylin-eosin

1 - capsule; 2 - cortical substance: 2.1 - glomerular zone, 2.2 - beam zone, 2.3 - mesh zone; 3 - medulla; 4 - sinusoidal capillaries

Rice. 176. Ultrastructural organization of cells of the adrenal cortex (corticosterocytes)

Drawings with EMF

Cells of the cortical substance (corticosterocytes): A - glomerular, B - fascicular, C - reticular zone

1 - core; 2 - cytoplasm: 2.1 - cisterns of the agranular endoplasmic reticulum, 2.2 - cisterns of the granular endoplasmic reticulum, 2.3 - Golgi complex, 2.4 - mitochondria with tubular-vesicular cristae, 2.5 - mitochondria with lamellar cristae, 2.6 - lipid drops, 2.7 - lipofuscin granules

Hormones - substances produced by the endocrine glands and released into the blood, the mechanism of their action. The endocrine system is a collection of endocrine glands that produce hormones. sex hormones.

For normal life, a person needs a lot of substances that come from the external environment (food, air, water) or are synthesized inside the body. With a lack of these substances in the body, various disorders occur that can lead to serious diseases. Among these substances synthesized by the endocrine glands within the body are hormones .

First of all, it should be noted that in humans and animals there are two types of glands. Glands of one type - lacrimal, salivary, sweat and others - secrete the secret outward and are called exocrine (from the Greek exo- outside, outside crino- highlight). The glands of the second type release the substances synthesized in them into the blood washing them. These glands are called endocrine (from the Greek endon- inside), and the substances released into the blood - hormones.

Thus, hormones (from the Greek hormaino- set in motion, induce) - biologically active substances produced by endocrine glands (see Figure 1.5.15) or special cells in tissues. These cells can be found in the heart, stomach, intestines, salivary glands, kidneys, liver and other organs. Hormones are released into the bloodstream and act on the cells of target organs located at a distance, or directly at the site of their formation (local hormones).

Hormones are produced in small amounts, but long time remain in an active state and are carried throughout the body with the blood stream. The main functions of hormones are:

- maintaining the internal environment of the body;

- participation in metabolic processes;

- regulation of growth and development of the body.

A complete list of hormones and their functions are presented in Table 1.5.2.

Table 1.5.2. Major Hormones

The structure of the endocrine system. Figure 1.5.15 shows the glands that produce hormones: the hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, ovaries (in women) and testicles (in men). All glands and cells that secrete hormones are united in the endocrine system.

The link between the endocrine and nervous systems is the hypothalamus, which is both a nerve formation and an endocrine gland.

He controls and unites endocrine mechanisms regulation with nervous, being also the brain center autonomic nervous system . The hypothalamus contains neurons that are capable of producing special substances - neurohormones that regulate the secretion of hormones by other endocrine glands. The central organ of the endocrine system is also the pituitary gland. The rest of the endocrine glands are peripheral organs endocrine system.

Follicle stimulating and luteinizing hormones stimulate sexual functions and the production of hormones by the gonads. The ovaries of women produce estrogens, progesterone, androgens, and the testicles of men produce androgens.