The epithelial tissue covers the entire outer surface of the human body, lifts all body cavities. Wallows the mucous membrane of the hollow organs, serous shells, part of the organism's gland. Therefore, distinguish cooking and ironed epithelium.

The epithelial tissue is located on the border of the external and internal environment of the body. And participates in the exchange of substances between the organism and the external environment. Performs protectivethe role (skin epithelium). Performs functions suction(intestinal epithelium), discharge (renal channel epithelium), gas exchange(Epithelium Alveol Lights). This fabric has high regeneration. Irony epithelium, which forms glands Able to allocate secrets. This ability to produce and highlight the substances necessary for life, call secretion. This epithelium is called secretor.

Distinctive signs of epithelial tissue:

- Pharmacy fabric is on the border of the external and inner environment of the body.

- It consists of epithelial cells These cells form solid layers.

- In these plastics no blood vessels.

-Food This fabric happens by diffusion through the basal membrane, which separates the epithelial tissue from the loose connective tissue under it and serves as a support of the epithelium.

IN pokrovnaepitheliums allocate single-layer epithelium and multi-layered.

IN one-layer Epitheli All cells are located on the basal membrane.

IN multilayer Epithelia on the basal membrane lies only the bottom layer of cells. The upper layers are lost with it and form several layers.

Single-layer Epithelium happens single row and multiple.

Epithelium cells - epithelial cells. In epithelial cells allocate two parts. 1. Basal The part is directed towards the fabric. 2. Apical Part is facing a free surface. The basal part lies the kernel.

In the apical part is organhall, inclusion, microwaves, cilia. In the form of cells of the epithelium happens flat, cubic, cylindrical (prismatic).

Fig. # 1. Types of epithelium.

Single-layer adhesive epithelium– mesothelium - Covers serous shells - purevra, Epicard, peritoneum.

Single-layer flat epithelium – endothelium - Woven mucous membrane Blood and lymphatic vessels.

Single-layer cubic Epithelium covers kidney Channels, Retreats Great and small bronchi.

Single-layer prismatic Epithelium Woven the mucous membrane of the stomach.

Single-layer prismatic caming Epithelium Woven the intestinal mucous membrane.

Single-layer multi-row prismatic seating Epithelium covers pumps and respiratory tract.

Multilayer flat epitheliumon the sign of the erochive of the upper layers of cells divide on introging and non-cooperating.

Multilayer flat ornamental epithelium – epidermis. It covers the skin surface. The epidermis consists of many tens of cell layers. On the skin of the skin cells are dying, turning into horny flakes. They destroys the kernel and cytoplasm and keratin accumulates.

Multi-layered flat non-propelled epithelium She lins the cornea of \u200b\u200bthe eye, the cavity of the mouth, esophagus.

There is a transitional form of multilayer epithelium - transition. He covers the urinary paths - renal loch, bladder, i.e. Organs capable of changing their volume.

Irony epithelium It is the main mass of the organism. The glands in the body perform a secretory function. The secret to them is necessary for the processes occurring in the body. Some glands are independent bodies, such as pancreas, large salivary glands. Other glands are part of the organs, for example, the gland of the intestinal wall, stomach. Most glasses are derived epithelium.

Distinguish glands external secretion - exocrine.They have output ducts and highlight their secret in body cavities or to the surface of the body. These are dairy glands, sweat, salivary.

there is the glands of the internal secretion - endocrine. They do not have output ducts and allocate their secret to the inner medium of the body - blood or lymph. Their secret - hormones.

There are glands of mixed secretion.They have endocrine and exocrine parts, such as pancreas.

Figure No. 2. Types of glands.

Exocrine glands are very diverse. Highlight unicellular and multicellular glands.

Unicellular glands - Wildlife cells are located in the intestinal epithelium, respiratory tract they produce mucus.

In multicellular glands distinguished secretarial department and output duct.The secretory department consists of cells - glandulocytes who produce a secret. Depending on whether the shared duct branches or not, allocate simple and complex glands.

In the form of a secretory department distinguish tubular, alveolar and alveolar and tubular glands.

Depending on how the secret is formed and how it is released from the cells, distinguish murcinic, apokrin and holocrine glands.

Meroccian The glands are most common. They allocate their secret in the duct without the destruction of cytoplasm of secretory cells.

In apokrinov The glands occurs partial destruction of cytoplasm of secretory cells. The apical part of the cell is destroyed and is part of the secret. Then the destroyed cell is restored. Such iron includes dairy and sweat glands.

In Gololine The glands allocation of the secret is accompanied by cell death. These destroyed cells are the secreted gland. Such glands include sebaceous glands.

By the nature of the secret disassemble mucous, protein and mixed (protein-mucous)glands.

Fabric determination, classification, functional differences.

The fabric is a combination of cells and an intercellular substance having the same structure, functions and origin.

Tissue classificationThere are several tissue classifications. The most common is the so-called morphofunctional classification, which has four groups of tissues:

epithelial fabrics;

connective tissues;

muscle tissue;

nervous fabric.

Epithelial fabrics Characterized by combining cells into the layers or heavy. The metabolism between the organism and the external environment is performed through these fabrics. Epithelial tissues perform protection, suction and excretion. Sources of the formation of epithelial tissues are all three germinal leaf - Ektoderma, Mesoderma and Entoderma.

Connecting fabrics (actual connecting fabrics, skeletal, blood and lymph)develop from the so-called embryonic connective tissue - mesenchyms. The inside fabrics are characterized by the presence of a large amount of the intercellular substance and contain various cells. They specialize in performing trophic, plastic, reference and protective functions.

Muscular fabrics Specialized in performing the function of movement. They develop mainly from the mesoderm (transversely stacked tissue) and mesenchyma (smooth muscle tissue).

Nervous fabricdevelops from ectoderma and specializes in performing a regulatory function - perception, and transmit information

Epithelial tissue in the body, types, functions, structure.

Epitheliums cover the surface of the body, serous body cavities, internal and outdoor surface Many internal organsForming secretory departments and output ducts of exocrine glands. The epithelium is a reservoir of cells under which there is a basal membrane. Epitheliaare divided by pokrovnythat linen the body and all cavities available in the body and ferrouswhich produce and distinguish the secret.

Functions:

1. Reminted / barrier / (contact with the external environment);

2. Protective (internal environment of the body from the damaging effect of mechanical, physical, chemical factors of the medium; the production of mucus with antimicrobial effect);

3. The exchange of substances between the organism and the environment;

4. Secretor;

5. Excretory;

6. Development of sex cells, etc.;

7. Receptor / sensory /.

The most important properties of epithelial fabrics:considered cell location (epithelocytes),forming layers, the presence of well-developed intercellular connections, location on basal membrane(Special structural education, which is located between the epithelium and the loose fibrous connective tissue), the minimum amount of the intercellular substance, border position in the body, polarity, high ability to regenerate.

general characteristics. Epithelial fabrics communicate with the body with an external environment. The epithelium is located in the skin, lifts the mucous membranes of all internal organs, is part of the serous shells; He has the functions of suction, isolation, perception of irritation. Most of the organism glands are built from epithelial tissue.

All germ sheets are involved in the development of epithelial tissue: Etoderma, Mesoderma, Entoderma. Mesenchym does not participate in the laying of epithelial tissues. If the organ or its layer is a derivative of an outdoor germs, such as skin epidermis, then its epitheliums develop from ectoderma. The epithelium of the gastrointestinal tube has an entodermal, and the epithelium of the urinary system is a mesodermal origin.

All epitheliums are built from epithelial cells - epithelial cells.

Epithelocytes are firmly connected to each other with the help of desmosom, closure belts, gluing belts and by interdagating.

Dosemomomomomomy There are point structures of the intercellular contact, which, like rivets, fasten the cells in various tissues, mainly in the epithelial.

Intermediate connection or zooming seedsZonula Adherens- Clutch lines).

This type of compound is found most often on the side surface of the epithelial cells between the area of \u200b\u200bthe location of the dense compound and the des #. This connection covers the cell around the perimeter as a belt. In the intermediate area, plasmolm leafles addressed to the cytoplasm are thickened and form plates of attachments that contain actin-binding proteins.

Dense connection Zonula Occludens- closure of closures).

This type of contacts refers to the so-called dense contacts. In contacts of this kind, cytoplasmic membranes of neighboring cells seemed to merge. At the same time, an exceptionally dense docking of cells is formed. Such contacts are most common in the tissues in which it is necessary to completely prevent the penetration of metabolites between cells (intestinal epithelium, endothelium of the horn shell). As a rule, the compounds of this type are located on the apical surface of the cell, sliding it. The closure of the closure is an area of \u200b\u200bpartial fusion of external leaflets by plasmolm of two adjacent cells.

InterDigitating (finger connections). Interdagation is intercellular compounds formed by the protrusions of the cytoplasm of some cells, which are in the cytoplasm of others.

Epithelocytes form cellular reservoir, functioning and regenerating (Regeneratio - renewal, revival) as a whole. Usually, epithelial layers are located on the basement membrane, which, in turn, lies on the loose connective tissue of the epithelium.

Basal membrane - This is a thin unstructure layer with a thickness of about 1 μm. Chemical composition: Glycoproteins, proteins, various proteoglycans. Oxidative, hydrolytic and other enzymes contained in the basal membrane are characterized by high activity.

The chemical composition and the structural organization of the basal membrane determine its functions - transport of macromolecular compounds to the creation of an elastic base for epithelocytes.

In the formation of the basal membrane, both epithelocytes and the underlying connecting tissue take part.

Epithelial tissue is powered by diffusion path: nutrients and oxygen penetrate the basal membrane to epithelocytes from loose connective tissue, intensively equipped with a capillary network.

Epithelial tissues are characterized by polar differentiation, which is reduced to a different structure or layers of the epithelial formation, or epithelocyte poles. If all cells lie in the epithelial formation on the basement membrane, polar differentiation is the different structure of the surface (apical) and internal (basal) cell poles. For example, on the apical pole of the plasmolm form a suction cut or flickering cilia, and in the basal pole are the kernel and most of the organelle

Common morphological signs of epithelium as fabric:

1) epithelialocytes are arranged tightly to each other, forming the cells of the cells;

2) for epithelials, the presence of a basal membrane is characterized by a special non-global education, which creates the basis for the epithelium, provides barrier and trophic functions;

3) there is practically no intercellular substance;

4) between cells are intercellular contacts;

5) For epithelocytes, polarity is characterized - the presence of functionally unequneable cell surfaces: the apical surface (pole), the basal (facing the basal membrane) and the lateral surface.

6) Vertical anisomorphism - unequal morphological properties of cells of various layers of epithelial formation in multilayer epitheliums. Horizontal anisomorphism - unequal morphological properties of cells in single-layer epitheliums.

7) There are no vessels in the epithelium; Power supply is carried out by diffusion of substances through a basal membrane from connective tissue vessels;

8) For most epitheliums, a high ability to regenerate is physiological and reparative, which is carried out due to cambial cells.

The surface of the epitheliocyte (basal, lateral, apical) has a distinct structural and functional specialization, which is particularly well detected in single-layer epithelium, including in the glandular epithelium.

3. Classification of the cover epithelium is one-layer, multi-layered. Irony epithelium.

I. Cover epithelium

1. Single-layer epitheliums - all cells lie on the basement membrane:

1.1. Single-row epitheliums (cell cores at one level): flat, cubic, prismatic;

1.2. Multi-row epithelium (cell cores at different levels due to horizontal anisomorphism): Prismatic semicircle;

2. Multilayer epitheliums - only the lower layer of cells is associated with the basal membrane, the overlying layers are located on the underlying layers:

2.1. Flat - oroging, non-refined

3. Transitional epithelium - occupies an intermediate position between single-layer multiple and multilayer epithelium

II. Ferrous epitheliums:

1. With exocrine secretion

2. With endocrine secretion

Single-layer single-row flat epithelium Educated by composed polygonal cells. Examples of localization: mesothelium covering light (visceral pleura); Epithelium, lining from the inside, breast cavity (parietal pleura), as well as parietal and visceral leaflets of the peritoneum, a challenge bag. This epithelium allows the authorities to contact each other in the cavities.

Single-layer single row cubic epithelium Educated by cells containing a spherical core. Examples of localization: follicles thyroid gland, small pancreatic ducts and bile ducts, renal tubules.

Single-layer single-row prismatic (cylindrical) epithelium Educated by cells with a pronounced polarity. The core of the ellipsis form lies along the long axis of the cell and is shifted to their basal part, organelles are unevenly distributed over the cytoplasm. On the apicial surface there are microvilles, brush cut. Examples of localization: liner of the inner surface of thin and colon, stomach, gallbladder, row of large pancreas ducts and bile ducts Liver. For this type of epithelium characteristic of secretion and (or) suction features.

Single-layer multi-row column (flickering) epithelium The air pathways are formed by cells of several types: 1) Low inserts (basal), 2) high insert (intermediate), 3) semi-cake (flicker), 4) glassworms. Low insert cells are cambial, they will arrive with their wide base to the basement membrane, and do not reach the narrow apical part to the lumen. Wildlife cells produce a mucus that covers the surface of the epithelium by moving over the surface due to the bias of flicker cilias. The apical parts of these cells borders with the lumen of the organ.

Multilayer flat ornamental epithelium (MPE) forms an outer layer of skin - epidermis, and covers some areas of the mucous membrane of the oral cavity. Meko consists of five layers: basal, hiped, grainy, brilliant (not everywhere) and horny layers.

Basal layerformed by cubic or prismatic cells lying on the baseal membrane. Cells are divided by mitosis - this is a cambial layer from which all overlying layers are formed.

Hipgy layereducated by large cells of the wrong shape. In deep layers there may be divided cells. Tonophybrilles are well developed in the basal and prudet layers (bundles of the tunes), and between the cells are des #omomal, dense, sliding contacts.

Granular layerit consists of flattened keratinocyte cells, in the cytoplasm of which contains grains of keratogial - fibrillar protein, which in the eleidine and keratin and keratin.

Brilliant layerit is expressed only in the epithelium of thick skin, covering palms and soles. The brilliant layer is the zone of transition from living grain layer cells to the scales of the horn layer. In histological preparations, it has a narrow oxyphyl homogeneous strip and consists of flattened cells.

Horny layerconsists of horny scales - post-cell structures. Enot processes begin in a thunder layer. The horny layer has a maximum thickness in the epidermis of the skin of the palms and the sole. The essence of keratinization is to ensure the protective function of the skin from external influences.

Differon keratinocyteincludes the cells of all layers of this epithelium: basal, vicious, grain, brilliant, horny. In addition to keratinocytes in multilayer orinnoying epitheliums are present in a small amount of melanocytes, macrophages (Langerhans cells) and Merkel cells (see the topic "Leather").

Ceratinocytes are dominated in the epidermis, organized by the core principle: cells on different stages Differentiations are located on each other. Based on the column - cambial unoccupied cells of the basal layer, the top of the column - the horny layer. The keratinocyte column includes cells of the Keratinocyte differ. The column principle of the organization of the epidermis plays a role in tissue regeneration.

Multi-layered flat non-propelled epithelium Covers the surface of the cornea of \u200b\u200bthe eye, the oral mucous membrane, esophagus, vagina. It is formed by three layers: basal, pricked and superficial. The basal layer is similar in the structure and function to the corresponding layer of the epithelium. The hipped layer is formed by large polygonal cells, which, as the surface layer approached the surface layer. Their cytoplasm is filled with numerous te-imaging, which are diffuse. The surface layer consists of polygonal flat cells. The core with poorly distinguishable chromatin granules (picnotic). During desquamation, the cells of this layer are constantly removed from the surface of the epithelium.

Due to the availability and ease of obtaining the material, the multilayer flat epithelium of the oral mucosa is a convenient object for cytological studies. Cells are obtained by scuffing, smear or imprint. Next, we are transferred to the slide and prepare a permanent or temporary cytological preparation. The greatest distribution was diagnosed cytological research this epithelium in order to identify the genetic sex of the individual; Violations of the normal flow of the epithelium differentiation process in the development of inflammatory, prematubic or tumor processes of the oral cavity.

3. Transitional epithelium - a special kind of multilayer epithelium, which lins most urinary tract. It is formed by three layers: basal, intermediate and superficial. The basal layer is formed by small cells having a triangular shape on a slice and their wide base is adjacent to the baseal membrane. The intermediate layer consists of elongated cells, a narrower part of the gear membrane adjacent to the basal membrane. The surface layer is formed by large single-core polyploid or duid cells, which mostly change their shape when tensile epithelium (from a round to flat). This is facilitated by the formation of these cells in the apical part of the cytoplasm of these cells at rest of the numerous invaginations of plasmolemma and special disk-shaped bubbles - plasmolymma reserves, which are embedded in it as organ and cells stretch.

Ferrous epitheliums

Irony epithelial cells can be placed one by one, but more often form glands. The cells of ferrous epithelium - glandulocytes or glandular cells, the process of secretion in them proceeds cyclically, is called a secretory cycle and includes five stages:

1. The phase of the absorption of the starting materials (from the blood or intercellular fluid), of which the final product is formed (secret);

2. The secrecy phase of the secret is associated with transcription and broadcast processes, the activities of GREPS and AGREPS, the Golgi complex.

3. The secretion phase of the secretion occurs in the Golgi apparatus: dehydration and addition of additional molecules occurs.

4. The phase of accumulation of the synthesized product in the cytoplasm of ferrous cells is usually manifested by increasing the content of secretory granules, which can be in the membrane.

5. The sharing phase can be carried out in several ways: 1) without disrupting the integrity of the cell (the murcinite type of secretion), 2) with the destruction of the apical part of the cytoplasm (the apocryan type of secretion), with a complete violation of the cell integrity (holocrine secretion type).

Epithelial fabric or epithelium form external and internal coverings of the body, as well as most glands.

Epithelial fabric functions

• protective (barrier);
• secretory (secrete a number of substances);
• excretory (allocates a number of substances);
• suction (epithelium gastrointestinal tract, oral cavity).

Structural and functional features of epithelial tissues

• epithelial cells are always placed;
• epithelial cells are always located on the baseal membrane;
• epithelial fabrics do not contain blood and lymphatic vessels, exception, vascular strip inner ear (Cortis organ);
• epithelial cells are strictly differentiated to the apical and basal pole;
• epithelial tissues have a high regenerator capacity;
• in epithelial tissue, there is a predominance of cells over the intercellular substance or even its absence.

Structural components of epithelial tissue

1. Epithelocytes - are the main structural elements of epithelial tissues. Located in epithelial formations closely and are interconnected various types Intercellular contacts:

• simple;
• desmosomes;
• dense;
• slim-like (Nexus).

To the basal membrane, the cells are attached via semiasis. In various epitheliums, and often in one type of epithelium, contain different types of cells (several cell populations). In most epithelial cells, the kernel is localized basal, and in the apical part there is a secret that produces a cell, in the middle there are all other cells of the cells. This characteristic of each type of cells will be given when describing a specific epithelium.

1. The basal membrane is a thickness of about 1 microns, consists of:

• thin collagen fibrils (from type 4 collagen protein);
• amorphous substance (matrix) consisting of a carbohydrate-protein-lipid complex.

Classification of epithelial tissues

• coating epitheliums - forming external and internal covers;
• ferrous epitheliums are the constituent majority of the organism.

Morphological classification Cover epithelium:

• single-layer flat epithelium (endothelium - wipes all the vessels; mesothelium - widespread natural cavities: pleural, abdominal, pericardial);
• single-layer cubic epithelium - epithelium of renal tubules;
• single-layer single-row cylindrical epithelium - kernels are located at one level;
• single-layer multi-row cylindrical epithelium - kernels are located at different levels (pulmonary epithelium);
• multilayer flat ornamental epithelium - leather;
• multi-layered flat non-peer epithelium - oral cavity, esophagus, vagina;
• transitional epithelium - the shape of the cells of this epithelium depends on functional state organ, for example, bladder.

Genetic classification of epithelials (by N. G. Chlopin):

• epidermal type, develops from ectoderma - multilayer and multi-row epithelium, performs a protective function;
• enterodermal type, develops from the Entoderma - a single-layer cylindrical epithelium, performs the process of suction of substances;
• tableprodermal type - develops from mesoderma - a single-layer flat epithelium, performs barrier and excretory functions;
• ePENDIMOGLIAL TYPE, develops from neuroectoderma, lifts the cavities of the head and spinal cord;
• angiodermal type - endothelium of vessels, develops from mesenchym.

Irony epithelium

forms the overwhelming majority of the organism. Comprises:

• glandular cells - glandulocytes;
• basal membrane.

Classification of glands:

1. By the number of cells:

• single-celled (glazing gland);
• the multicellular is the overwhelming majority of the glands.

1. By the method of deriving secrets from the gland and on the structure:

• ecocrine glands - have derived duct;
• endocrine glands - do not have output duct and distinguish between increments (hormones) in blood and lymph.

Ecocrine glands Consist of terminal or secretory departments and output ducts. End departments May be in the form of the alveoli or tube. If one terminal department opens in the output duct - iron simple unbranched (alveolar or tubular). If several end departments open in the output duct - iron simple branched (alveolar, tubular or alveolar-tube). If the main output duct branches - Iron is complex, it is branched (alveolar, tubular or alveolar-tube).

Phases of the secretory cycle of ferrous cells:

• absorption of the initial products of secret formation;
• synthesis and accumulation of secret;
• allocation of secretion (for a frozin or apokrinov type);
• restoration of the glandular cell.

Note: Cells secreting in holocrine type ( song hardware) Completely destroyed, and from cambial (spiked) cells are formed new ferrous sledges.

Epithelial fabrics (epitheliums) cover the surface of the body, linse the shells of the internal organs, the most of the glands. They are divided into coating and ferrunts. Pockery epitheliums occupy a spoken position in the body, separated the inner medium from external, participate in suction and allocation functions. Blood epithelium performs protective functions, preventing the body from external influences.

Features of the structure:

1. Cells close to each other and lie on the basal membrane;

2. There are practically no intercellular between the cells, they are firmly connected to each other with the help of special contacts;

3. In epithelial cells, there are no blood and lymph-tichetic vessels, nutrients and oxygen pro-niche to epithelial cells from the subject-loose connective tissue;

4. Cell change due to the ability of epithelial cells to rapid reproduction (mitotic division).

There are one-layer and multilayer epithelium. In single-layer epitheliums, all cells lie on the basal membrane, and in multilayer with the basal membrane, only the lower (deep) layer is connected.

Irony epithelium. The cells of the ferrous epithelium are performed by the functions of formation (synthesis) and the separation of specific substances - secrets to the surface of the skin, mucous membranes or in blood, lymph. These substances are enjoying important functions in the life of the body: protect the surface of the body, contain digestive enzymes and other biologically active substances. From secretory cells built glands that are subdivided into two groups. The glands of external secretion (exocrine) and the inner secretion gland (endocrine) are distinguished. Excree glands allocate their secret on the surface of the body covered with epithelium. Ecocrine glands include sweat and sebaceous glands, whose secret is released on the surface of the skin, as well as salivary, gastric, intestinal glands, etc., which highlight their secret to the surface of the mucous membranes of internal organs. Material from site.

Endocrine glands do not have output ducts, their biologically active substances (hormones) come directly into the blood of blood capillaries, which are soaked. Endocrine glands: pituitary gland, thyroid gland, adrenal glands, etc.

In the human body there are mixed glands. For example, the pancreas consists of an exocrine part, whose secret stands out in the lumen thin gut, and endok ringed, highlighting their hormones in blood.

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On this page, material on the themes:

• human epithelial tissue.eline
• summary about epithelial tissue
• single-layer epithelial tissue structure
• the structure of the epithelial tissue of man
• localization of epithelial tissue

Epithelial fabrics are divided into superficial, including coating and lining, and ironed epithelium. Pokrovnaya- this is the skin epidermis, lining - This is the epithelium covering the cavities of various organs (stomach, bladder et al.), fermented - part of the glands.

Surface epithelium located on the border between the inner and external environment and performs the following functions: Protective, barrier, receptor and exchange, since the nutrients are absorbed through the epithelium (intestinal) into the body and through the epithelium (renal) methods of metabolism.

Irony epithelium It is part of glands that produce secrets and hormones necessary for the body, i.e. performs a secretory function.

Surface epithelium differs from other tissues with six main features:

1) is located in layers;

2) lies on a basal membrane consisting of an amorphous substance comprising proteins, lipids and carbohydrates, fibronectins, lamininis, as well as thin fibrils containing type IV collagen; The basal membrane consists of a light and dark layers and performs functions: barrier, trophic, exchange, anti-invasive, morphogenetic; attaches the epithelium formation; Under the basal membrane, connective tissue is always located;

3) There is no intercellular substance in it, so the epithelial cells are tightly adjacent to the friend and connect with the help of intercellular contacts:

a) dense (Zonula Accludens),

b) gear or finance (Junctio intercellularis denticulatae),

c) desmosoma and others;

4) the absence of blood vessels, since the power of the epithelium is carried out on the side of the connective tissue through the basal membrane;

5) epithelial cells possess polar differentiation, i.e. each cell has a basal end facing the basal membrane, and the apical end facing the opposite direction, which is explained by the border position of the tissue; In the cytolemma of the basal part of the cell sometimes there is a basal aestracy, on the side surface - intercellular contacts, on the apical surface - microville, in some cases forming the suction cut;

6) The coating epithelial tissue has a high ability to regenerate.

Classification of epithelial surface tissues. Epithelial surface tissues are classified for 2 signs:

1) depending on the structure of epithelial tissue and the relationship to the basal membrane;

2) depending on the origin (phylogenetic classification by N. G. Chlopin).

Morphological classification. Surface epithelium is divided into one-layer and multilayer.

Single-layer epithelium In turn, divided into single-row and multi-row, or pseudomnographed. Single-row epithelium It is divided into flat, cubic and prismatic, or column. Non-row epitheliumalways prismatic.

Multilayer epithelium Unit on a multi-layered flat burner, a multi-layered flat, non-illuminating, multilayer cubic (multi-layer prismatic is always non-propelled) and, finally, transitional. The name is flat, cubic or prismatic depends on the shape of the cells of the surface layer. If the surface layer of the cells has a compiled shape, then the epithelium is called flat, and all the underlying layers may have a different form: cubic, prismatic, incorrect, etc. Single-layer epithelium differs from multilayer in that all its cells are located on the basement membrane, Time as in multilayer epithelium, only one basal cell of the cells is associated with the basal membrane, and the remaining layers are located one on the other.

Phylogenetic classification by N. G. Chlopin.According to this classification, 5 varieties of epithelial tissues are distinguished:

1) epidermal epithelium - develops from ectoderm (for example, skin epithelium);

2) enterodermal epithelium - develops from the Entoderma and lifts the middle department of the gastrointestinal tract (stomach, thin and thick intestines);

3) Cherefrodermal epithelium - develops from the Mesoderm and lifts the pleura, peritoneum, pericardium, renal tubules;

4) EPENDIMOGLIAL Epithelium - develops from the nervous tube, lifts the ventricles of the brain and the central canal of the spinal cord;

5) Angiodermal epithelium - develops from mesenchym, linges heart chambers, blood and lymphatic vessels.

Single-layer flat epithelium Epithelium Squamosum Simplex) is divided into endothelium (endothelium) and mesothelium (mesothelium).

Endothelium It develops from the mesenchym, the hearts, blood and lymphatic vessels sweeps. Endothelius cells - endotheliocytes have an irregularly blended shape, the edges of the cells are rolled, contain one or more flatted nuclei, the cytoplasm is poor to organogelles of the general value, contains many pinocytous bubbles. In the luminal surface of the endotheliocytes there are short microvills. What luminal surface? This surface facing the body's clearance, in this case, the blood vessel or to the heart chamber.

Endothelium function - exchange of substances between blood and the surrounding cloth. In case of damage to the endothelium in the vessels, throms are formed, blocking their lumen.

Mesothelium (mesothelium) develops from the leaflets of the splash, lifts the peritoneum, pleura, pericardium. Mesotheliocyte cells have a composed incorrect shape, the edges of the cells are cut; Cells contain one by one, sometimes several of the flatted nuclei, the cytoplasm of the poor and the general value organelles, there are pinocytous bubbles, indicating the exchange function; In the luminal surface there are microvills that increase the surface of the cells. The mesothelium function is to ensure the smooth surface of the serous shells. This facilitates the gliding organs in the abdominal, chest and other cavities; Through the mesothelium, the metabolism between serous cavities and the connective tissue of their walls occurs. Mesothelium secretes the liquid contained in these cavities. In case of damage to the mesothelium between serous shells, spikes can be formed, impede the movement of organs.

Single-layer cubic epithelium (Epithelium Cuboideum Simplex) is available in renal tubules, leafing output. The shape of cubic cells, the kernels are round, developed organelles of the total value: mitochondria, EPS, lysosomes. On the apical surface there are numerous microwaves that form a running outage (Limbus Striatus) rich in alkaline phosphatase (SHF). In the basal surface there is basal allocations (Stria Basalis), which is the folds of cytlemmas, between which mitochondria are located. The presence of a fulfilled car wash on the surface of the epithelocytes indicates the absorption function of these cells, the presence of basal aperture - about reabsorption (reverse absorption) of water. The source of the development of the renal epithelium is mesoderma, or rather, nephrogenic fabric.

Column epithelium (Epithelium columnare) is located in a thin and thick intestine and stomach. Column (prismatic) stomach epithelium She lins the mucous membrane of this organ, develops from intestinal entoderma. The cells of the epithelium of the gastric mucous membrane have a prismatic form, an oval kernel; In their light cytoplasm, the smooth EPS, the Golgi and Mitochondria complex, in the apical part there are secretory granules containing a mucous secret. Thus, the surface epithelium of the gastric mucosa is glazed. Therefore, its functions:

1) secretory, i.e., the development of the mucous membrane, enveloping the gastric mucosa;

2) Protective - mucus secreted by ferrous epithelium protects the mucous membrane from chemical and physical influences;

3) Water, glucose, alcohol, alcohol is absorbed through the cover (it's iron).

Stamp (cut) epithelium of thin and large intestines (Epithelium Columnare Cum Limbus Striatus) wipes the mucous membrane of the thin and colon, develops from intestinal entoderma; Characterized by what has a prismatic form. The cells of this epithelium are connected to each other using dense contacts, or closure plates, i.e., the intercellular slots are closed by contacts. Organelles of general meaning are well developed in the cells, as well as the tonophylants that form the cortical layer. In the region of the side surfaces of these cells, closer to their base, there are desmosomoms, finger-shaped, or gear, contacts. On the apical surface of the columnar epitheliumodites there are microvilles (up to 1 μm and a diameter of up to 0.1 μm), the distance between which is 0.01 microns and less. These microwaves form a suction, or a running, drill (Limbus Striatus). Functions of the cacular epithelium: 1) Prieucous digestion; 2) suction of splitting products. Thus, a sign confirming the absorption function of this epithelium is: 1) the presence of absorption kaimki and 2) alositeness.

The epithelial of the thin and large intestines includes not only the columnar epithelocytes. Between these epithelial cells also have glassoid epithelioliocytus (EpithelioCytus Caliciformis) performing the function of separation of the secrecy of the secret; Endocrine cells (Endocrino-Cyti), producing hormones; Unfifferentiated cells (stem), devoid of cuts that perform a regenerator function and at the expense of which the intestinal epithelium is updated for 6 days; In the epithelium of the gastrointestinal tract cambial (stem) cells are located compactly; Finally, there are cells with acidophilic graininess.

Pseudo-layer (multi-row) epithelium(Epithelium pseudostratificatum) is one-layer, since all its cells lie on the basement membrane. Why then this epithelium is called multi-row? Because his cells have various shapes and sizes, and, therefore, their kernels are located at different levels and form the ranks. The kernels of the smallest cells (basal, or short inserts) are located closer to the basement membrane, the medium cell cores (long inserted) are localized above, the kernel of the highest cells (semicolored) are most removed from the basal membrane. The multi-row epithelium is located in the trachea and bronchi, the nasal cavity (develops from a precrowdal plate), in men's seed-winning paths (develops from the mesoderm).

In multi-row epithelium distinguishes 4 varieties of cells:

1) EpithelioCytus Ciliatus;

2) small and large inserted cells (epithelioocytus intercalatus parvus et epithelioocytus intercalatus magnus);

3) Wide beams (exocrinocytus calciformis);

4) Endocrine cells (Endocrinocytus).

Epitheliocytes - These are the highest cells of the pseudo-layer epithelium of the mucous membrane of the respiratory tract. The cores of these cells have an oval shape and, as already mentioned, are most removed from the basal membrane. In their cytoplasm there are general importance organelles. The basal narrow end of these cells is associated with the basal membrane, on a wide apical end there are cilia (Cilii) with a length of 5-10 μm. Each cilia is based on the axial thread (Filamenta Axialis), which consists of 9 pairs of peripheral and 1 pairs of central microtubules. The axial thread is connected to the basal tel (modified centriol). Cilia, carrying out vibrational movements, directed against the inhaled air, remove dust particles that have trachea and bronchi on the surface of the mucous membranes.

Epitheliocytes also consist of the epithelium of the mucous membrane of the uterine pipes and the uterus, although this epithelium does not apply to the multi-row.

Small insert cells The respiratory tract is the smallest, have a triangular shape, a wide basal end lie on the basal membrane. Function of these cells - regenerator; They are cambial, or stem, cells. In the trachea, bronchops, nasal cavity and epidermis of the skin Cambinal cells are diffuse.

Large insert cells Above small inserts, but their apical part does not reach the surface of the epithelium.

Box and shaped cells (Exocrinocytus Caliciformis) is ferruginous cells (single-cell glands). Before these cells did not have time to accumulate, they have a prismatic form. In their cytoplasm there is a nucleus of a flattened shape, a smooth EPS, the complex Gjjji and Mitochondria are well developed. In their apical part, the granules of the mucosa secret are accumulated. As these granules accumulate, the apical part of the cell is expanding and the cell is becoming the type of glasses, why is the name of a glassworm. The function of hemous-shaped cells-allocation of the mucous membrane, which, enveloping the mucous membrane of the trachea and bronchi, protects it from chemical and physical influences.

Endocrinocytes In the composition of the multi-row epithelium of the respiratory tract, otherwise called basal-grain or chromaffinic cells, they perform a hormonal function, that is, they allocate noreproynaline hormones and serokonin, which regulate the reduction of the smooth muscles of the bronchi and trachea.