The histological structure of the rest of the face of the picture scheme. Endocrine system

03.03.2020

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Ministry of Health of the Russian Federation

State budgetary educational institution

higher professional education

"Tyumen State Medical Academy"

Department of Histology with Embryology. prof. P.V. Dunaev

Parathyroid gland

Executor:

student 136 gr.

pediatric faculty

Rustamova S.M.

Lecturer: Schidin. V.A.

1. Development source

2. Topography

3. Anatomical structure

4. Histological structure

5. Function

7. Symptoms and treatment

Literature

1. Development source

Parasitovoid glands develop from the epithelium of the 3rd and 4th pairs of gill pockets, pharyngeal bags. Their primitives appear between the 3rd and 4th weeks of embryonic development. At the ends of the 3rd pair of gill pockets appears on the dorsal increase, which is soon separated and strongly shifted caudally, differentiate into the lower parachitoid glands. The upper pair of parachitoid glands develops from the 4th pair of gill pockets.

2. Topography

Parasitovoid glands are paired formations located in the neck area behind thyroid gland. Their quantity ranges from 2 to 6, often glands 4, two top and two lower. There are glands in a loose connective fiber separating the inner and outer capsules of the thyroid gland. The upper pair is adjacent to the rear of the thyroid gland, near their tops, approximately at the level of the arc of the pisteward cartilage. The lower pair is between the trachea and the shares of the thyroid gland, near their grounds. Rarely parathyroid glands are directly in the parenchyma of the thyroid gland.

3. Anatomical structure

Fig. 1: Parasitovoid Iron

Parasite glands - the two top and two lower - are small formations of the value of rice grains, which occur behind the thyroid rates, having a rounded or oval form. Their number varies: 50% - two, 50% - four, is usually constant to the upper steam.

Average dimensions: Length - 4-5 mm, thickness - 2-3 mm, weight - 0.2-0.5 gr. The lower parachitoid glands are usually larger than the upper. Parasitovoid glands differ from the thyroid gland with lighter color, in children pale-pinkish, in adults - yellow-brown and more dense consistency.

Like all glands, parachitoid glands have a thin connective tissue capsule, from which partitions dividing the fabrics on cells of cells, but there is no clear distinction on the slices.

Fig. 2: 1 - Upper parachite glands, 2 - thyroid gland, 3 - lower parathyroid glands, 4 - Harness

4. Histological structure

Parasitovoid glands, like the thyroid gland, are represented by follicles, Fig.1.57, b, but the colloid contained in them is poorly poor. Parenchima gland consists of a dense mass of epithelial cells, paratyrocytes: main and acidophilic. Hence their name "Epithelial Taurus". Acidophilic cells are aging main cells.

Among the main cells divided into bright and dark, light cells are most active in functionality. Currently, it is believed that both types of cells are essentially the same cells at different stages of development.

Fig.3: 6 - follicles of the thyroid gland; 7 - parathyroid iron; 8 - oxyfly cells; 9- main cells; 10 -capillyers; 11 -Kapsula.

5. Function

Parasitovoid iron regulates the calcium level in the body in a narrow framework, so that the nervous and motor systems function normally. When the calcium level in the blood drops below a certain level, the receptors of the parachite gland, sensitive to calcium, are activated and secreted by hormone into the blood.

Parathghammon stimulates osteoclasts so that they are isolated into the blood of calcium calcium from bone tissue. The physiological value of the parathyroid gland consists in secretion by it by paranthormon and calcitonin, which is its antagonist. These hormones together with vitamin D are involved in the regulation of calcium exchange and phosphorus in the body. Congenital absence or underdevelopment of parathyroid glands, lack of them as a result surgical removal, violations of the secretion of the parathgamon, as well as a violation of sensitivity to it, tissue receptors lead to the pathologies of phosphorous calcium exchange in the body and the development of endocrine diseases (hyperparathyroidism, hypoparathyroidism), eye diseases (cataracts).

parasite Iron Adenoma hyperplasia

6. Parashotoidoid hormone

We produce parathyroid hormone or parathgaron.

The main function of the pararatgomon is to maintain a constant level of ionized calcium in the blood and this function it performs, affecting the bones, kidneys, and by vitamin D - on the intestine. As is well known, there are about 1 kg of calcium in the human body, 99% of which is localized in the bones in the form of hydroxyapatite. About 1% of the calcium organism is contained in soft tissues and in the extracellular space, where it takes part in all biochemical processes.

Parathgarmon:

We are needed to maintain the concentration of calcium ions in the blood at the physiological level.

The reduction in the level of ionized calcium in the blood activates the secretion of the parathgamon, which increases the release of calcium from the bone due to the activation of osteoclasts.

The level of calcium in the blood increases, but the bones lose their rigidity and easily deformed.

The hormone of the parachoid gland leads to the effects opposite to the effects of thyreocalcitonin secreted by the C-cells of the thyroid gland.

7. Symptoms and treatment

Adenoma and parachite gland hyperplasia

It is these two problems that cause violations of the functions of parathyroid glasses, manifested in increasing hormone products. Increased iron at hyperplasia produces more than the pararathgamon, and the adenoma produces it independently. Thus, the hyperfunction of the parathyroid gland is developing (hyperparathyroidism). The hormonally active cyst of the parachitoid gland also causes an excess of its hormones and hyperparathyroidism.

Manifestations of hyperparathyroidism

These manifestations are associated with an increase in the level of calcium in the blood due to increased content Hormones of parachitoid gland. An increase in the amount of calcium in the body leads to a mineral imbalance, which manifests itself primarily in the form of symptoms of bone and kidney damage.

Bone damage: demineralization, softening bones, fractures, osteoporosis.

Kidney lesions: renal colic, urolithiasis, chronic renal failure, nephroalcinosis, Uremia.

Hypercalcemia, to which hyperparathyroidism, causes other disorders: fast fatigue, reduction in memory, drowsiness, depression and psychosis, muscle weakness, disorders from the gastrointestinal tract.

In cases where the cause of the disease in the development of adenoma, all of the above symptoms are the symptoms of the parachite gland adenoma.

Hypoparatyosis

The pituitary gland gypofunction arising with the insufficient synthesis of the parathgamon leads to a lack of calcium. The cause may be the diseases of the thyroid gland, inflammation and tumor of the parachitoid gland. Treatment of diseases, during which the removal of parachitoid glands is also carried out, also becomes the cause of hypocalcemia.

The symptoms of the parachitoid gland in the case of hypocalcemia are mainly associated with neuromuscular manifestations: cramps, numbness, spasms.

Symptoms of hypocalcemia may be problems with vision, brain operation, cardiomegaly, pale dry skin, bad Growth teeth and others.

In more severe cases, the lack of calcium is manifested by epileptic seizures, but consciousness remains.

With suspected adena of the parachitoid gland, the scintigraphy of the parachitoid glands is performed. This diagnostic method allows to identify tumor formations and parachite gland hyperplasia. The sensitivity of this method is 93%, at the moment it is the most reliable for the diagnosis of parathyroid glands.

Scanning is made after the introduction of the radiopharm drug. Conclusions are made based on comparing images with minimal and maximum accumulation of the drug in tissues.

In addition, a clinical analysis of blood is done to identify the number of hormones, ultrasound of parachite gland.

Based on the diagnosis, the treatment of parachite gland is prescribed.

Treatment methods

· Medical (correction of the level of the parathgamon),

· Surgical (operation on parachite gland)

Treatment of the adenoma of the parachitoid gland is always carried out surgical method. The removal of the adenoma of the parachitoid gland is performed. In the course of the operation, inspection of all the glands to eliminate all adenoma if necessary.

In some cases, part of the parachitoid gland or all iron is removed. Since there are several of them (usually four), then the remaining can take on the function of lost. But most often they do not cope with the load, and life without parachite gland is complicated by hypoparathyroidism and hypocalcemia.

For more than 20 years, clinical and experimental studies on transplanting parachitoid glasses and their fragments began. Transplantation of the parasite glands in many cases gives a good effect in the treatment of hypoparathyroidism.

Literature

1. http://www.biletomsk.ru.

2. http://ru.wikipedia.org.

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Histology

Histology from Greek Histos Fabric Logos Teaching Science on the structure of the development and life of fabrics of living organisms .. The formation of histology is closely related to the development of microscopic equipment and .. In the history of the teachings on tissues and microscopic structure of organs, two periods of the dominder and the microscopic structure are distinguished.

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Kernel (everything about him)
The core component of the cell, which contains genenet. Material. The functions of the kernel: storage, implementation, genet transmission. The core of the core consists of: Caryolamma-nuclear shell

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Iron - the name of this endocrine organ recently on the hearing. This is due to the sad statistics of the dissemination of the disease "thyroid". In the same article, we will introduce you in detail with the importance of this body, the alarming symptoms of his "troubleshooting", deciphering histological research and many others.

What is thyroid gland?

The thyroid gland is an internal secretion body, an important part of the endocrine system of the body. Her task is the synthesis of hormones that support the organism homeostasis. In particular, it produces iodine-containing elements that are responsible for the growth of cells and metabolism in the body. But about the functions and hormones of the thyroid gland later.

The mass of the organ - 20-65, it depends on the age of a person - significantly hesitate in size. For example, during puberty, its volume and weight is significantly increased. And to the old age of iron begins, on the contrary, decrease. Women "thyroid" can be increased during pregnancy and 1-2 years after childbirth.

The structure of the organ

On the structure, the thyroid gland reminds the butterfly-plated wings. The symmetric organ - consists of two pieces and a carriage between them. The shares are located on both sides of the trachea, and the experienses adjacent to it.

The location and structure of the thyroid gland is different in two floors:

Women: a little large in size than men's, but also subcutaneous fat fabric, protecting the body, also volumetric, why "the thyroid" in the female half less notable. Location: front and side of the thyroid and hand-shaped cartilage.
In men: Located just below these cartilage, in some cases it comes to sternum.

The role of "thyroid" in the body

Speaking about hormones and the functions of the thyroid gland, the first thing should be allocated its most important task: the organ produces hormones that provide normal metabolism, due to the heart and gastrointestinal tract. The activity of the gland itself affects the level of iodine in the body.

The "thyroid" also helps the body performed by the following vital functions:

Adjusting the heart rate and respiration.
Ensuring the normal operation of the nervous system - central and peripheral.
Maintain proper body weight.
Periodicity of menstrual cycles.
Normal body temperature.
Uncritical level of cholesterol in the blood.
Regulation of consumption by oxygen cells. Therefore, in violation of the functions of the organ to cells, there is a smaller volume of oxygen, which is why free radicals begin to be copied to them, which causes a sense of constant fatigue, serves as the cause of other diseases.

Hormones produced by thyroid

Specifically, the thyroid gland produces three hormones:

T4 - thyroxine. Its function: the absorption of fatty essential acids by the body and the metabolism of fats. The slowdown in the same fat exchange leads to an increase in cholesterol.
T3 - triiodothyronine. 20% of this hormone in the body produces directly "thyroid", the rest - derivatives T4. Regulation of metabolism and cell activity.
Participated in the regulation of the desired share of calcium in the body.

Causes of organ disease

The reasons why the disease is developing and, accordingly, the hystology of the thyroid gland is required, several:

Inflammation of the organ itself.
Insufficient / excess iodine in the body.
Corollary of medical procedures: surgery, radiation therapy, receiving a number of drugs.
Dysfunction of the immune system.
Pregnancy. The diseases "fraught" by the fact that they can lead to miscarriage, premature childbirth or to the birth of a dead baby.

Alarm symptoms

Typical general symptomatics Thyroid problems as follows:

Lost, scattered, fatigue, worsening memory, the ability to concentrate attention.
Weight loss.
Violation of sexual functions, hormonal failure.
Constipation.
Muscular pain constantly freezing limbs.
Brush nails, dull, dropping hair.
Pucheglasie.
Rhythm heart rhythm.
Visual increase in the body.

"Thyroid" diseases

Diseases of various gravity, to recognize which, among other things, the histology of the thyroid gland will help, several.

Hyperthyroidism. The organ produces excessive amounts of hormones. The patient feels and observes with this disease:

nervousness;
intolerance to the heat;
constant fatigue;
sweating;
weight loss;
skin itch;
heartbearance;
hair loss.

Hypothyroidism. Iron produces an insufficient number of hormones. The disease often passes in a hidden form - it does not know about her for years. It reveals its simple type of diagnosis - screening test on T4. The symptoms are as follows:

constant depression;
fast fatiguability;
hair cover;
hodged sensitivity;
dry skin;
in women - irregular periods.

Goiter. Edema of the gland whose cause is a lack of iodine in the body. Sometimes there is a consequence autoimmune disease. Causes can be the following:

appearance of nodules on the gland;
abuse smoking;
infections;
hormonal penalty;
radiation therapy;
reception of drugs containing lithium.

Thyroid cancer. What is worth noting - oncology here develops very slowly, follicular and papillary tumors today are easily amenable to therapy. Only poorly differentiated tumors are unfavorable for the patient - due to active metastasis. For diagnostics, the histology of the thyroid node is needed. The symptoms of cancer are as follows:

On the neck appears a small non-painless lump.
Lymph nodes around the neck increase.
Permanent pain in the neck, throat.
Labored breathing.
Hoarse voice.

Diagnostics

With the appearance of any signs hinting for the disease "thyroid", it is worth consulting an endocrinologist as soon as possible, which first of all must appoint comprehensive diagnosis, incl. Histological analysis (histology) of the thyroid gland.

Diagnostic methods are divided into physical, laboratory and instrumental. Among them:

palpation;
linked immunosorbent assay;
tomography;
thermography;
scintigraphy;
aspiration biopsy;
tests for determining the level of thyroxine;
determination of iodine excretion with urine.

We will talk in detail about histological examination.

Histology of thyroid gland

More correctly - biopsy with this analysis makes it possible to find out whether a malignant tumor "thyroid". Andocrinologist is prescribed when nodes or a cyst on the organ more than 1 cm in diameter.

If the formation is malignant, then the doctor prescribes the operation to the patient. However, this method of research is applied not only when diagnosing, but also during operational intervention - In order for the surgeon to quickly identify exactly where the malignant neoplasm. Histology of the thyroid gland is carried out after the operation - whether everything you need is removed and you do not need a new surgical intervention.

How is the histology?

For research, the patient take the histological apparatus - a sample of the cells of the "thyroid". How is the histology of the thyroid gland? A procedure is performed by aspirational thin biopsy, under the control of the Uz-apparatus. The procedure is painless, takes 2-5 seconds.

The syringe with an ultrathin needle doctor makes a puncture in the area of \u200b\u200bthe gland and resets the required amount of sample for the study. Further, the material is examined without the participation of the patient.

Decoding results

Of course, the interpretation of the conclusion is the prerogative of an experienced specialist. But the pre-approximate thyroid gland is under power and patient:

- The reason to calm down. This means that education is benign. The accuracy of the formulation of this diagnosis is 98%.
"Follicular epithelium", "colloid" - it is also about benign tumor. Accuracy - 95%.
"The node with the symptomatics of the proliferation of the epithelium of follicular, atypics" or "difficulty with differentiation of carcinoma and adenoma" is about follicular neoplasia. The probability of presence of malignant education is 50%.
"Malignant cannot be excluded" - a 70% probability of the presence of cancer cells.
"Suspicion of carcinoma" - 90% chance of oncology.
Just the word "carcinoma" - almost 100% probability of gland cancer, the inevitability of the operation.

In any case, it is not necessary to succumb to a panic: the likelihood that a specialist in the fence of the material, when conducting a study, could allow an error. If the conclusion indicates the presence of malignant tumorThe endocrinologist usually directs the patient to negate histology.

Treatment of "thyroid" mainly consists in medication hormone therapy. With its failure, surgery is appointed, the modern version of which allows you to transfer it excellent. Also, the removal of the gland or its part, radiation therapy is prescribed during the oncological lesions of the organ.

IN follicular complexes, or microdols, which consist of a group of follicles surrounded by a thin connective tissue capsule can be distinguished by the thyroid gland.

IN the colloid is accumulating the follicles - a secretory product of thyrocytes, which is a viscous liquid consisting mainly of Tyroglobulin. The size of follicles and forming them by thyrocytes varies in normal physiological conditions. In small forming follicles, not yet filled with colloid, single-layer prismatic epithelium. As the colloid accumulates the size of follicles increases, the epithelium becomes cubic, and in strongly stretched follicles filled with colloid, the epithelium becomes flat. The bulk of the follicles is normal formed by the cubic formathy. The increase in the size of the follicles is due to proliferation, growth and differentiation of thyrocytes, accompanied by the accumulation of colloid in the follicular cavity.

Follicles are separated by thin layers of loose fibrous connective tissue with numerous blood and lymphatic capillaries that are powered by follicles, as well as fat cells and lymphocytes.

Follicular endocrinocytes, or thyrocytes, are ferruginous cells that make up most of the wall of follicles. In follicles, thyrocytes are located in one layer on the basement membrane.

Tyrocytes change their shape from flat to cylindrical depending on functional state glands. With moderate functional activity of the thyroid gland, thyrocytes have a cubic shape and spherical cores. The colloid, secreted by them, fills in the form of a homogeneous mass of the magnitude of the follicle. On the apical surface of thyrocytes facing the lumen of the follicle, there are microvils. As thyroid activity gained, the number and dimensions of the microwave increase. The basal surface of thyrocytes facing the surface of the follicle is almost smooth. Neighboring thyrocytes are closely related to numerous desmosms and well-developed terminal plates. As the thyroid activity increases on the side surfaces of the thyrocytes, the finance protrusions (or interdigate) are arising, which are included in the appropriate pressure of the lateral surface of adjacent cells.

The function of thyrocytes is the synthesis and isolating iodine-containing thyroid hormones - T3, or triiodothyronine, and T4, or thyroxine.

IN tyrocytes are well developed by organelles, especially participating in protein synthesis. Protein products synthesized by thyrocytes are released into the follicle cavity, where the formation of iodized tireosins and tironins is completed (ie, amino acids that are part of a large and complex Tyroglobulin molecule). Thyroid hormones may fall into circulation only after release from this molecule (that is, after the splitting of Tyroglobulin).

Solina Anna, TGMA, lep. Fak.

When the needs of the body in the thyroid hormone increase and the functional activity of the thyroid gland is enhanced, the tyrocytes of follicles take the prismatic form. The intrafollicular colloid at the same time becomes more liquid and permeated with numerous resorption vacuoles.

The weakening of the functional activity (hypofunction) of the thyroid gland is manifested, on the contrary, the seal of the colloid, its stagnation inside the follicles, the diameter and volume of which are significantly increasing; The height of thyrocytes decreases, they take a compiled shape, and their kernels are pulled in parallel to the follicle surface.

In a secretory cycle of follicular endocrinocytes, two main phases are distinguished: the product phase and the relief phase of hormones.

The product phase includes:

The receipt of Tyroglobulin predecessors (amino acids, carbohydrates, ions, water, iodides), brought from the bloodstream in Tombocytes;

The synthesis of the chiper oxidase enzyme, oxidizing iodide and providing them with a compound with tyroglobulin on the surface of the thyrocytes and in the follicle cavity and the formation of the colloid;

Synthesis of polypeptide chains of Tyroglobulin itself in the granular endoplasmic network and their glycosylation (i.e., a compound with neutral sugars and a sialic acid) with tyoroder oxidase (in the Golgi apparatus).

The removal phase includes the resorption of Tyroglobulin from the colloid by pinocytosis and its hydrolysis using lysosomal proteases to form thyroxine hormones and triiodothyronine, as well as the removal of these hormones through the basal membrane into hemokapillary and lymphocapyllars.

The pituitary thyroid hormone (TSH) increases the function of the thyroid gland, stimulating the absorption of Tyroglobulin microvils of thyrocytes, as well as its splitting in phagelicosomes with the release of active hormones.

Thyroid hormones (T3 and T4) are involved in the regulation of metabolic reactions, affect the growth and differentiation of tissues, especially the development of the nervous system.

The second type of thyroid endocrinocytes is parapolycular cells, or c-cells, or calcitoninocytes. These are cells of neural origin. Their main function is the production of thyreocalcitonin, which reduces the level of calcium in the blood.

In an adult body, paraphrolicular cells are localized in the wall of the follicles, clutching between the bases of neighboring thyrocytes, but do not reach their top of the lumen of the follicle. In addition, paraphrolicular cells are also located in interfollicular interfollicular layers of connective tissue. In size, parapollicular cells are larger than tyrocytes, they have a rounded, sometimes angular shape. Parapollicular cells carry out biosynthesis of peptide hormones -

Solina Anna, TGMA, lep. Fak.

calcitonin and somatostatin, and also participate in the formation of neuroamines (norepinerenaline and serotonin) by decarboxylation of the respective predecessor amino acids.

Secretor granules that fill in the cytoplasm of paraphrolular cells are detected by severe osmophilia and arginia (i.e., these cells are well detected when the osmia and silver salts are impregnated).

Vascularization. The thyroid gland is abundantly supplied with blood. For a unit of time through the thyroid gland, approximately the same blood passes, but through the kidneys, and the intensity of blood supply increases significantly in strengthening the functional activity of the organ.

Innervation. In the thyroid gland, many sympathetic and parasympathetic nerve fibers. Stimulation of adrenergic nerve fibers leads to a slight increase, and parasympathetic - to the oppression of the functions of follicular endocrinocytes. The main regulatory role belongs to a thyrotropic pituitary hormone. Parapollicular cells are immune to thyrotropic hormone, but clearly react to the activating sympathetic and inhibitory parasympathetic nerve impulses.

The regeneration of the thyroid gland under physiological conditions is carried out very slowly, but the ability of Parenhim to proliferate is large. The source of growth of thyroid parenchyma is the epithelium of follicles. The violation of the mechanisms of regeneration can lead to the growth of the gland with the formation of goiter.

Porish-shaped (parachitoid) glands

Porish-shaped glands (usually in the amount of four) are located on the rear surface of the thyroid gland and are separated from it capsule.

The functional importance of the nearby hair is in the regulation of calcium metabolism. They produce protein hormone paratyrin, or parathglon, which stimulates the resorption of the bone with osteoclasts, increasing the level of calcium in the blood. The osteoclasts themselves do not have receptors to the parathgormon, is its action indirectly by other bone tissue cells - osteoblasts.

In addition, pararathgamon reduces the removal of calcium with kidneys, and also enhances the synthesis of vitamin D metabolite, which, in turn, increases calcium absorption in the intestine.

Development. Porish-shaped glands are laid by the embryo as the protrusions from the epithelium of the III and the IV-born Park of the Gill Pockets. These protrusions are packed, and each of them develops into a separate pan-shaped gland, and from the IV pair of gill pockets develops the upper pair of glands, and from III couple The lower pair of nearby glands is developing, as well as the fork iron - thymus.

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The structure of the porous gland.Each nearby-shaped iron is surrounded by a thin connective tissue capsule. Its parenchyma is represented by Trabezlas - epithelial hoodies of endocrine cells - pararatocytes. Trabecules are separated by thin layers of loose connective tissue with numerous capillaries. Although intercellular gaps are well developed between paratyrocytes, neighboring cells are associated with interdigations and desmoms. There are two types of cells: the main paratyrocytes and oxipal pararaths.

The main cells secrete paratyrin, they prevail in the parenchyma gland, have small sizes and polygonal shape. In the peripheral zones of the basophils cytoplasm, where the clusters of free ribosomes and secretory granules are scattered. With the strengthening of the secretory activity of the parachitoid glands, the main cells increase in volume. Among the main paratyrocytes are also distinguished by two types: bright and dark. In the cytoplasm of light cells there are inclusions of glycogen. It is believed that bright cells are inactive, and dark cells are functionally active pararaths. The main cells are carried out by biosynthesis and selection of the parathgamon.

The second type of cells is oxyphibal pararatchites. They are small, are arranged by one or groups. They are much larger than the main paratyrocytes. In the cytoplasm, oxyfly granules are visible, a huge amount of mitochondria in the weak development of other organelles. They are considered as aging forms of main cells. In children, these cells are single, with age, their number increases.

The secretory activity of the near-face glands does not affect the pituitary hormones. Porish-shaped iron on the principle of feedback quickly responds to the slightest oscillations in the level of calcium in the blood. Its activity is enhanced in hypocalcemia and weakened with hypercalcemia. Pararatocytes have receptors capable of directly perceiving the direct influence of calcium ions on them.

Innervation. Porish-shaped glands receive abundant sympathetic and parasympathetic innervation. Mineral fibers end with terminals in the form of butt or rings between paratyrocytes. Around oxyphibal cells, nerve terminals take the look of the basket. There are also encapsulated receptors. The effect of incoming nerve impulses is limited by vascular effects.

Age-related changes. In newborns and young children, only the main cells are found in the parenchyma of the nearby gland. Oxyfly cells appear no earlier than 5-7 years, by this time their quantity increases rapidly. After 2025, the accumulation of fat cells will gradually progress.

Solina Anna, TGMA, lep. Fak.

Adrenal glands

The adrenal glands are endocrine glands, which consist of two parts - cortical and cerebral substances with different origins, structure and function.

Building. Outside, adrenal glands are covered with a connective tissue capsule, in which two layers differ - outer (dense) and internal (more loose). Thin trabecules, carrier vessels and nerves depart from the capsule in the cortical substance.

The adrenal cortical substance occupies most of the gland and highlights corticosteroids - a group of hormones affecting different kinds exchange immune system, the flow of inflammatory processes. The function of the adrenal cortex is controlled by the adrenocorticotropic hormone of pituitary gland (ACTH), as well as kidney hormones - a renin angiotensin system.

IN catecholamines (adrenaline, or epinephrine, and norepinephrine, or norepinephrine) are produced by the cerebral substance, which affect the speed of heart cuts, the reduction of smooth muscles and the metabolism of carbohydrates and lipids.

The development of adrenal glands takes place in several stages.

The cortical part bookmark appears at the 5th week of the intrauterine period in the form of thickening of the niccomic epithelium. These epithelial thickens are assembled into a compact interrenal body, - primary (fetal) adrenal cortex.

From the 10th week of the intrauterine period, the cellular composition of the primary bark is gradually replaced and gives the initiate definitive adrenal cortex, the final formation of which occurs during the first year of life.

IN fetal adrenal cortex are synthesized mainly glucocorticoids - precursors of female sex hormones placenta.

From the same nominal epithelium, from which the interrenal body arises, sex rollers are also laid - the rigs of the gonad, which causes their functional relationships and the proximity of the chemical nature of their steroid hormones.

The brain part of the adrenal glands is laid by the human embryo on the 6-7th week of the intrauterine period. Of the overall primators of the sympathetic ganglia, which is located in the aortic area, neuroblasts are evicted. These neuroblasts are introduced into an interrenal body, proliferate and give the beginning of the brain part of the adrenal glands. Consequently, the glandular cells of the brain part of the adrenal glands should be considered as neuroendocrine.

Cork substance of adrenal glands. Cork endocrinocytes form epithelial chips, oriented perpendicular to the surface of the adrenal gland. The gaps between epithelial jets are filled with loose connective tissue, which pass the blood capillaries and nerve fibers that are tuned.

Under the connective tissue capsule there is a thin layer of small epithelial cells, the reproduction of which is ensured by the regeneration of the bark and

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the possibility of the appearance of additional interrenal calves, sometimes detected on the surface of the adrenal glands and often turning out by sources of tumors (including malignant).

IN adrenal cortex There are three main zones: glomeric, bundled and mesh.

IN they are synthesized and distinguished by various groups of corticosteroids - respectively: mineralocorticoids, glucocorticoids and genital steroids. The source substrate for the synthesis of all these hormones is cholesterol extracted by cells from the blood. Steroid hormones are not covered in cells, but are formed and stand out continuously.

Surface, the glomeric zone is formed by small cortical endocrinocytes that form rounded arches - "glitter".

IN the glomerular zone is produced by mineralocorticoids, the main of which is aldosterone.

The main function of mineralocorticoids is to maintain electrolyte homeostasis in the body. Mineralocorticoids affect the reabsorption and excretion of ions in the renal tubules. In particular, Aldosterone increases the reabsorption of sodium ions, chlorine, bicarbonate and enhances the excretion of potassium and hydrogen ions.

A number of factors affect the synthesis and secretion of aldosterone. Epiphyse hormone Adrenoglomerulotropin stimulates the formation of aldosterone. The components of the recennangiotenzine system are stimulating the influence on the synthesis and secretion of aldosterone, and the braking - sodium-ethical factors. Prostaglandins can have both stimulating and inhibiting influence.

In the hypersection of aldosterone, sodium delay in the body determines the increase arterial pressure, and loss of potassium accompanied by muscle weakness.

With a reduced secretion of aldosterone, sodium loss accompanied by hypotension, and potassium delay leading to heart rate disabilities. In addition, mineralocorticoids increase inflammatory processes. Mineralocorticoids are vital. Destruction or removal of the glomerular zone leads to a fatal outcome.

Between the glomerular and beam areas there is a narrow layer of small minority cells. It is called intermediate. It is assumed that the reproduction of cells of this layer ensures replenishment and regeneration of the beam and mesh zones.

The average, the bundled zone occupies the middle part of epithelial seewer and is most pronounced. Cell cells are separated by sinusoid capillaries. Cork endocrinocytes of this zone are large, oxyfly, cubic or prismatic form. The cytoplasm of these cells contain a large number of lipid inclusions, the smooth EPS is well developed, mitochondria have characteristic tubular crystons.

Solina Anna, TGMA, lep. Fak.

IN glucocorticoid hormones are produced by the beam area: corticosterone, cortisone and hydrocortisone (cortisol). They affect the metabolism of carbohydrates, proteins and lipids and strengthen the processes of phosphorylation. Glucocorticoids enhance gluconeogenesis (glucose formation due to proteins) and glycogen deposition in the liver. Large doses of glucocorticoids cause the destruction of lymphocytes and blood eosinophils, as well as inhibit inflammatory processes in the body.

Third, mesh adrenal cortex zone. In it, epithelial shutters branch, forming a loose network.

IN the mesh zone is produced by sex steroid hormones with androgen action. Therefore, tumors of adrenal cortex in women are often the cause of virilism (the development of secondary sexual signs of male, in particular the growth of mustache and beard, voting changes).

Brainstuffs of adrenal glands.The brainstant is separated from the cortical substance with a thin intermittent interruption of connective tissue. In the cerebral substance, the hormones of "acute" stress - catecholamines are synthesized and highlighted - i.e. Adrenaline and Noradrenalin.

This part of the adrenal glands is formed by the accumulation of relatively large cells of the rounded shape - chromaffinocytes, or feochromocytes, between which there are special blood vessels - sinusoids. Among the brain cells differ light - epinephrorsites secreting adrenaline, and dark - norepinephrocytes secreting norepinephrine. Cell cytoplasm thick filled with electron-containing secretory granules. The core of the granules is filled with protein accumulating secreted catecholamines.

The brainstant cells of the adrenal glands are well detected when impregnation with salts of heavy metals - chromium, osmium, silver, which has reflected in their name.

Electron-dense chromaffine granules, in addition to catecholamines, contain peptides - enkephalins and chromographers, which confirms their belonging to the neuroendocrine cells of the APUD system. In addition, in the brainstant there are multipolar neurons of the autonomous nervous system, as well as supporting crippled cells of clay nature.

Catecholamines affect the smooth muscle cells of the vessels, the stomaching path, the bronchi, on the heart muscle, as well as the metabolism of carbohydrates and lipids.

Education and emissions in the blood of catecholamines are stimulated when activating the sympathetic nervous system.

Age-related changesin adrenal glands. The bark of adrenal glands in humans reaches full development aged 20-25 years, when the ratio of the width of its zones (glomerular

to puchkova to the mesh) approaches 1: 9: 3 value. After 50 years, the width of the bark begins to decrease. In the cortical endocrinocytes gradually decrease

the number of lipid inclusions, and the connecting interlayers between

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epithelial heavy thickens. This reduces the volume of the mesh and partly the glomerular zone. The width of the bulk zone relatively increases, which provides sufficient intensity of the glucocorticoid function of the adrenal glands until old age.

The brain part of the adrenal glands does not undergo pronounced age-related changes. After 40 years, some hypertrophy of chromaffinocytes is observed, but only in the old age, atrophic changes occur in them, the synthesis of catecholamines weakens, and signs of sclerosis are found in the vessels and brainstorm vessels.

Vascularization. The brain and cortical adrenal substance has a general blood supply. Arteries included in the adrenal gland are branched on arterioles that make up a dense subcapsular network from which the capillaries are deployed supplying bodies. Their endothelium is phenostrite, which facilitates the receipt of cortical steroid hormones from cortical endocrinocytes in blood flow. From the mesh zone, the capillaries come in a brain part, where they take the type of sinusoids and merge into venules, which are transferred to the venous plexus of the brainstant. Along with them, the arteries originate from the subcapsular network also come to the brain part. Passing through the bore and enriching the products secreted by adrenoccocations, the blood brings to chromaphifinocytes special, enzymes produced in the crust, which activate norepinenaline methylation, i.e. Adrenaline formation.

In the brain part, the branching of blood vessels is such that each chromaffinocyte is in one end in contact with the arterial capillary, and the other addressed to the venous sinusoid, which highlights catecholamines. Venous sinusoids are collected in the central vein of the adrenal gland flowing into the lower hollow vein. Thus, corticosteroids and catecholamines are coming to circulation at the same time, which ensures the possibility of joint action of both regulatory factors on effector organs or systems. According to the other veins, the blood from the crust and brainstant is heading to the petition vein, bringing adrenaline into it (increasing mobilization of glycogen glucose) and glucocorticoids, stimulating glukegenesis in the liver.

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The histological structure of the rest of the face of the picture scheme. Endocrine system

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