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

In the organism of mammalian animals and humans, 4 types of fabrics are isolated: epithelial, connective, in which bone, cartilage and fatty tissue can be distinguished; Muscular and nervous.

Fabric - location in the body, species, functions, structure

Tissue is a system of cells and an intercellular substance having the same structure, origin and function.

The intercellular substance is the product of the vital activity of the cells. It provides communication between cells and forms a favorable environment for them. It can be liquid, for example, blood plasma; amorphous - cartilage; structured - muscle fibers; Firmly - bone tissue (in the form of salt).

Fabric cells have a different shape that determines their function. Fabrics are divided into four types:

• epithelial - Border fabrics: leather, mucous;
• connecting - the internal environment of our organism;
• muscle;
• nervous fabric.

Epithelial fabric

Epithelial (border) tissues - linse the surface of the body, mucous membranes of all internal organs and cavities of the body, serous shells, and also form glands of external and internal secretion. The epithelium, lining the mucous membrane, is located on the baseal membrane, and the inner surface is directly addressed to the external environment. Its nutrition is performed by diffusion of substances and oxygen from blood vessels through the basal membrane.

Features: Many cells, the intercellular substance is small and it is represented by the basal membrane.

Epithelial tissues perform the following functions:

• protective;
• excretory;
• suction.

Classification of epithelium. By number of layers, one-layer and multi-layer differ. The form differences: flat, cubic, cylindrical.

If all epithelial cells reaches a basal membrane, it is a single-layer epithelium, and only the cells of one row are associated with the basal membrane, and others are free, it is multilayer. Single-layer epithelium can be single-row and multi-row, which depends on the level of the location of the nuclei. Sometimes a single-core or multi-core epithelium has fixed cilia facing an external environment.

Multilayer epithelium epithelial (cover) fabric, or epithelium, is a borderline layer of cells, which lifts the cover of the body, the mucous membranes of all internal organs and cavities, and also forms the basis of many glands.

Irony epithelium epithelium separates the body (inner medium) from the external environment, but simultaneously serves as an intermediary in the interaction of the body with the environment. The epithelium cells are tightly connected to each other and form a mechanical barrier that prevents the penetration of microorganisms and alien substances into the body. Epithelial tissue cells live a short time and are quickly replaced with new ones (this process is called regeneration).

The epithelial tissue is also involved in many other functions: secretions (gland of external and internal secretion), suction (intestinal epithelium), gas exchange (lung epithelium).

The main feature of the epithelium is that it consists of a continuous layer of tightly adjacent cells. Epithelium can be in the form of a formation of cells lining all the surfaces of the body, and in the form of large cell clusses - glands: liver, pancreas, thyroid, salivary glands, etc. In the first case, it lies on the basement membrane, which separates the epithelium from the subjectable tissue . However, there are exceptions: epithelial cells in lymphatic tissue alternate with elements of connective tissue, such an epithelium is called atypical.

Epithelial cells located with a formation can lie in many layers (multilayer epithelium) or in one layer (single-layer epithelium). The cell height differences flat, cubic, prismatic, cylindrical.

Single-layer flat epithelium - lins the surface of serous shells: pleura, lung, pericard, pericard hearts.

Single-layer cubic epithelium - forms the walls of the kidney tubules and output grooves.

Single-layer cylindrical epithelium - forms a gastric mucosa.

The divided epithelium is a single-layer cylindrical epithelium, on the outer surface of the cells of which there is a drive formed by microvills that ensure the absorption of nutrients - lins the small intestine mucosa.

The flicker epithelium (semi-epithelium) is a pseudo-layer epithelium, consisting of cylindrical cells, the inner edge of which, i.e., facing the cavity or channel, is supplied by constantly by oscillating hair-like formations (cilia) - cilias provide the movement of the egg in the pipes; In the respiratory tract removes microbes and dust.

The multilayer epithelium is located on the border of the body and the external environment. If the epithelium processes are processed, i.e., the upper cells of the cells turn into horny scales, then such a multi-layer epithelium is called a damage (skin surface). Multilayer epithelium widespread mouth mucosa, food cavity, horny eyes.

Transitional epithelium lifts the walls of the bladder, kidney pelvis, ureter. When filling these organs, transitional epithelium is stretched, and cells can move from one row to another.

Irony epithelium - forms glands and performs a secretory function (there is a substance - secrets that are either removed into the outer medium, or enter blood and lymph (hormones)). The ability of cells to produce and identify the substances necessary for the life of the body, is called secretion. In this regard, such an epithelium also received the name of the secretory epithelium.

Connective tissue

The connecting tissue consists of cells, an intercellular substance and connective tissue fibers. It consists of bones, cartilage, tendons, bundles, blood, fat, it is in all organs (loose connective tissue) in the form of the so-called stroma (frame) organs.

In contrast to epithelial tissue in all types of connective tissue (except fat), the intercellular substance prevails over cells in volume, i.e. the intercellular substance is very well expressed. The chemical composition and physical properties of the intercellular substance are very diverse in various types of connective tissue. For example, blood - cells in it "float" and move freely, since the intercellular substance is well developed.

In general, the connecting tissue is what is called the inner medium of the body. It is very diverse and is represented by various species - from dense and loose forms to blood and lymphs whose cells are in liquid. The principal differences in the types of connective tissue are determined by the ratios of cellular components and the nature of the intercellular substance.

In dense fibrous connective tissue (muscle tendons, ligaments), fibrous structures are dominated, it is experiencing significant mechanical loads.

Loose fibrous connecting tissue is extremely common in the body. It is very rich, on the contrary, cellular forms of different types. Some of them are involved in the formation of fabric fibers (fibroblasts), others, which is especially important, provide primarily protective and regulatory processes, including through immune mechanisms (macrophages, lymphocytes, tissue basophiles, plasmacites).

Bone

Bone tissue bone tissue, forming a skeleton bone, is characterized by great strength. It supports the form of the body (constitution) and protects the bodies located in the cranial box, the chest and pelvic cavities, participate in the mineral exchange. The fabric consists of cells (osteocytes) and an intercellular substance in which the nutritional channels with vessels are located. The intercellular substance contains up to 70% of mineral salts (calcium, phosphorus and magnesium).

In its development, the bone tissue passes the fibrous and lamellar stage. In different parts of the bone, it is organized in the form of a compact or spongy bone substance.

Cartilage fabric

The cartilage tissue consists of cells (chondrocytes) and an intercellular substance (cartilage matrix) characterized by increased elasticity. It performs a reference function, as it forms the main mass of the cartilage.

Three varieties of cartilage tissue are distinguished: a guialic, part of the cartilage trachea, the bronchi, the ends of the ribs, the articular surfaces of the bones; elastic, forming ear shell and a haunter; Fibrous, located in intervertebral discs and connections of pubic bones.

Fat fabric

Fat fabric is similar to loose connective tissue. Cells are large, filled with fat. Fat fabric performs nutritious, forming and thermostatic functions. The adipose tissue is subdivided into two types: white and brown. A white fatty fabric prevails in a person, part of it surrounds the organs, while maintaining their position in the human body and other functions. The number of brown adipose tissue in humans is small (it is mainly in the newborn baby). The main function of the brown tissue is heat. Brown fatty tissue maintains the body temperature of animals during hibernation and the temperature of newborn children.

Muscle

Muscular cells are called muscle fibers, because they are constantly elongated in one direction.

The classification of muscle tissues is carried out on the basis of the structure of the tissue (histologically): according to the presence or absence of transverse allocations, and on the basis of a reduction mechanism - arbitrary (both in a skeletal muscle) or involuntary (smooth or heart muscle).

Muscular tissue has excitability and ability to actively reduce under the influence of the nervous system and some substances. Microscopic differences make it possible to highlight two types of this tissue - smooth (inexhaustible) and transverse (exhausted).

Smooth muscular tissue has a cellular structure. It forms muscle shells of the walls of the internal organs (intestines, uterus, bladder, etc.), blood and lymphatic vessels; Reducing it occurs involuntarily.

A transverse muscle tissue consists of muscle fibers, each of which is represented by many thousands of cells, sparing, except for their cores, in one structure. It forms skeletal muscles. We can cut them at their request.

A variety of transverse muscle tissue is a heart muscle, which has unique abilities. During life (about 70 years), the heart muscle is reduced by more than 2.5 million times. No other tissue has such strength potential. Cardiac muscular tissue has a cross-term allocated. However, in contrast to the skeletal muscle, there are special sections here, where muscle fibers are closed. Due to this structure, the reduction of one fiber is rapidly transmitted to the neighboring. This ensures the simultaneity of the reduction of large sections of the heart muscle.

Also, the peculiarities of the structure of muscle tissue are that its cells contain bunches of myofibrils formed by two proteins - actin and myosin.

Nervous fabric

The nervous fabric consists of two varieties of cells: nervous (neurons) and glial. The glial cells are close to neuron, performing support, nutritious, secretory and protective functions.

Neuron is the main structural and functional unit of nervous tissue. His main feature is the ability to generate nerve impulses and transfer the excitation to other neurons or muscular and iron cells of the working bodies. Neurons can consist of bodies and processes. Nervous cells are designed to carry out nerve impulses. Having received information on one section of the surface, the neuron quickly transfers it to another portion of its surface. Since neuron processes are very long, the information is transmitted over long distances. Most neurons have process of two types: short, thick, branching near the body - dendrites and long (up to 1.5 m), thin and branching only at the very end - axons. Axons form nerve fibers.

Nervous impulse is an electrical wave, running at high speed on the nerve fiber.

Depending on the functions performed and the features of the structure, all nerve cells are divided into three types: sensitive, motor (executive) and insert. Motor fibers that go in the peoples of the nerves transmit signals with muscles and glands, sensitive fibers transmit information about the state of the organs into the central nervous system.

Now we can combine all the information received into the table.

Type Types (Table)

Group of fabrics	Types of fabrics	Fabric structure	Location
Epithelium	Flat	The surface of the cell is smooth. Cells are tightly adjacent to each other.	Surface of the skin, mouth cavity, esophagus, alveoli, nephron capsules	Cooking, protective, excretory (gas exchange, urine release)
	Glandular	Breeded cells produce a secret	Skin glands, stomach, intestines, inland secretion glands, salivary glands	Selection (selection of sweat, tears), secretory (the formation of saliva, gastric and intestinal juice, hormones)
	Flickering (seeded)	Consists of cells with numerous hairs (cilia)	Airways	Protective (cilia delay and remove dust particles)
Connecting	Dense fibrous	Groups of fibrous, tightly lying cells without intercellular substance	Actually skin, tendons, bundles, blood vessel shells, cornea	Cover, protective, motor
	Loose fibrous	Lyricted fibrous cells intertwined with each other. Intercellular substance is structured	Subcutaneous fatty tissue, near-smooth bag, carrying out the nervous system	Connects the skin with muscles, maintains organs in the body, fills the gaps between the organs. Carries out thermoregulation of the body
	Cartilage	Live round or oval cells lying in capsules, intercellular substance dense, elastic, transparent	Intervertebral wheels, cartilage larynx, trachea, ear sink, surface of the joints	Smoothing the rubbing surfaces of bones. Protection against the deformation of the respiratory tract, ear-sinks
	Bone	Live cells with long processions, interconnected, intercellular substance - inorganic salts and protein Ossein	Skeleton bones	Reference, motor, protective
	Blood and Lymph.	Liquid junction tissue consists of uniform elements (cells) and plasma (liquid with organic and mineral substances dissolved in it - serum and fibrinogen protein)	Blood system of the whole organism	Decaying 2 and nutrients throughout the body. Collects CO 2 and dissimilating products. Provides the constancy of the inner medium, the chemical and gas composition of the body. Protective (immunity). Regulatory (humoral)
Muscular	Cross-striped	Multi-cylindrical cylindrical cells up to 10 cm lengths, held by transverse stripes	Skeletal muscles, heart muscle	Arbitrary movements of the body and its parts, facial people, speech. Incoming reductions (automatic) of the heart muscle for pushing blood through the heart chambers. Has properties of excitability and contractility
	Smooth	Single-core cells up to 0.5 mm length with pointed ends	Walls of the digestive tract, blood and lymphatic vessels, skin muscles	Involuntary reductions in the walls of internal hollow organs. Hair lifting
Nervous	Nervous cells (neurons)	Bodies of nerve cells, varied in shape and magnitude, up to 0.1 mm in diameter	Form gray substance of the head and spinal cord	Higher nervous activity. Communication of the body with an external environment. Centers conditional and unconditional reflexes. Nervous fabric has the properties of excitability and conductivity
		Short processes of neurons - tree-visiting dendrites	Connect with neighboring cells	Transfer the excitation of one neuron to another by establishing the relationship between all body bodies
		Nervous fibers - axons (neurites) - long neurons grows up to 1.5 m. In organs end in branchy nerve endings	Nerves of the peripheral nervous system that innervate all body bodies	Conducting the nervous system paths. Transmit excitation from the nervous cell to the periphery in centrifugal neurons; from receptors (innervated organs) - to the nervous cell on centripetal neurons. Insert neurons transmit excitation from centripetal (sensitive) neurons on centrifugal (motors)

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1. Building and basic cell properties.

2. Concept of tissues. Types of fabrics.

3. Building and function of epithelial tissue.

4. Types of epithelium.

Purpose: Know the structure and properties of the cell, types of fabrics. Present a classification of epithelium and location in the body. To be able to distinguish the epithelial fabric by morphological features from other tissues.

1. The cell is an elementary live system, the basis of the structure, development and vital activity of all animals and plants. Cell Science - Cytology (Greek. Sytos - Cell, Logos - Science). Zoologist T.shvann In 1839, for the first time formulated the cell theory: the cell represents the main unit of the structure of all living organisms, animal cells and plants are similar in their structure, there is no cell outside the cell. Cells exist as independent organisms (protozoa, bacteria), and in the composition of multicellular organisms, in which there are sex cells that serve for breeding and body cells (somatic), various structures and functions (nervous, bone, secretory, etc. ) Human sizes are in the range of 7 microns (lymphocytes) to 200-500 μm (women's egg, smooth myocytes). In the composition of any cell, proteins, fats, carbohydrates, nucleic acids, ATP, mineral salts and water. Of the inorganic substances in the cell contains the most water (70-80%), from organic proteins (10-20%). The main parts of the cell are: core, cytoplasm, cell shell (cytlemma).

CELL

Code of cytolem cytoplasm

Nucleoplasm - hyaloplasm

1-2 Entry - Organelles

Chromatin (endoplasmic network

ktolji complex

cell Center

mitochondria

lysosomes

special purpose)

Inclusion.

The core of the cell is in the cytoplasm and is delivered from it nuclear

shell - nucleasem. It serves as a place of concentration of genes,

the main chemical of which is DNA. The kernel regulates the shaping processes of the cell and all its life departures. Nucleoplasm ensures the interaction of various nuclear structures, nuclei participate in the synthesis of cell proteins and some enzymes, chromatin contains chromosomes with heredity carriers.

Hyaloplasma (Greek. Hyalos - Glass) - the main plasma of the cytoplasm,

it is a true internal cell medium. It combines all cellular ultrastructures (core, organelles, inclusions) and provides chemical interaction with each other.

Organelles (organoids) are constant cytoplasm ultrasters performing certain functions in the cell. These include:

1) The endoplasmic network is a system of branched channels and cavities formed by double membranes associated with the cellular shell. On the walls of the channels there are the smallest tales - ribosomes, which are centers of protein synthesis;

2) Complex K.Golji, or an internal strainer, - has grids and contains vacuoles of different values \u200b\u200b(lat. Vacuum - empty), participates in the excretory function of cells and in the formation of lysosomes;

3) Cellular center - cytocentr consists of a spherical dense body centrofer, inside of which 2 dense tanks are centriily connected with a jumper. Located closer to the kernel, takes part in cell division, providing a uniform distribution of chromosome between subsidiaries;

4) Mitochondria (Greek Mitos - thread, chondros - grain) have the kind of grains, sticks, threads. They are in the synthesis of ATP.

5) lysosomes - bubbles filled with enzymes that regulate

exchange processes in the cell and possess digestive (phagocytic) activity.

6) special purpose organelles: myofibrils, neurofibrils, tonofibrils, cilia, villi, flagellas performing specific cell function.

Cytoplasmic inclusions are non-permanent education in the form of

pellets, drops and vacuoles containing proteins, fats, carbohydrates, pigment.

The cell shell is a cytlemma, or plasmolm, covers the cell from the surface and separates it from the environment. It is semi-permeable and regulates the receipt of substances into the cell and the exit of them from it.

The intercellular substance is between cells. In some tissues, it is liquid (for example, in the blood), and in others it consists of an amorphous (structural) substance.

Any live cell has the following main properties:

1) the metabolism, or metabolism (main life property),

2) sensitivity (irritable);

3) the ability to reproduce (self-reproduction);

4) the ability to increase, i.e. an increase in the size and volume of cellular structures and the cell itself;

5) development ability, i.e. acquisition of a cell of specific functions;

6) secretion, i.e. separation of various substances;

7) movement (leukocytes, histiocytes, spermatozoa)

8) phagocytosis (leukocytes, macrophages, etc.).

2. Fabric is a cell system similar to origins), structure and functions. The composition of the fabrics also includes tissue fluid and productivity products of cells. The doctrine of tissues is called histology (Greek. HistOS - Fabric, Logos - Teaching, Science). In accordance with the features of the structure, functions and development distinguish the following types of fabrics:

1) epithelial, or covert;

2) connecting (internal medium tissue);

3) muscle;

4) nervous.

A special place in the human body is occupied by blood and lymph - liquid fabric performing respiratory, trophic and protective functions.

In the body all tissues are closely related to the morphologically

and functionally. Morphological connection is due to the fact that

tissues are part of the same organs. Functional communication

it is manifested in the fact that the activities of various fabrics that are part of

organs, agreed.

Cellular and non-tissue elements in the process of life

activities wear out and die off (physiological degeneration)

and restore (physiological regeneration). When damaged

the tissues also occur their recovery (reparative regeneration).

However, not all tissues this process proceeds the same. Epithelial

naya, connecting, smooth muscular tissue and blood cells regene

ruve well. Transverse muscle tissue is restored

only under certain conditions. In nervous tissue is restored

only nerve fibers. The division of nerve cells in the organism of an adult

man is not installed.

3. Epithelial tissue (epithelium) is a fabric covering the skin surface, a cornea of \u200b\u200bthe eye, as well as the lining of all cavities of the body, the inner surface of the hollow organs of the digestive, respiratory, urogenital systems is part of most organism glands. In this regard, the coating and hardware epithelium distinguish.

Cooking epithelium, being border tissue, carries out:

1) Protective function, prevention to be tissues from various external influences: chemical, mechanical, infectious.

2) the metabolism of the body with the environment, performing the functions of gas exchange in the lungs, suction in the small intestine, allocating the exchange products (metabolites);

3) Creating conditions for the mobility of internal organs in serous cavities: heart, lungs, intestines, etc.

Irony epithelium exercises a secretory function, i.e. reproduces and highlight specific products - secrets that are used in the processes occurring in the body.

Morphologically epithelial fabric differs from other body tissues with the following signs:

1) it always occupies a border position, since it is located on the border of the external and internal media;

2) it is the layers of cells - epithelocytes, which have a different shape and structure in various types of epithelium;

3) between the cells of the epithelium there is no intercellular substance, and cells

connected with each other with various contacts.

4) Epithelial cells are located on the basal membrane (a plate with a thickness of about 1 μm, which is separated from the subjectable tissue. The basal membrane consists of an amorphous substance and fibrillar structures;

5) epithelium cells have polarity, i.e. Basal and top cells of cells have a different structure; "

6) Epithelium does not contain blood vessels, so the power supply of cells

carried out by diffusion of nutrients through the basal membrane from the subjectable tissues; "

7) The presence of tonophybrils - the nital structures that attach the strength to epithelial cells.

4. There are several classifications of the epithelium, which are based on various signs: the origin, structure, functions. The morphological classification of them was the greatest distribution, which takes into account the ratio of cells to the basement membrane and their shape on the free apical (lat. Apex - Top) parts of the epithelial reservoir . This classification reflects the structure of the epithelium, depending on its function.

Single-layer flat epithelium is represented in the body endothelium and mesothelium. Endothelium swees the blood, lymphatic vessels, heart chambers. Mesothelium covers the serous shells of the cavity of the peritoneum, pleura and pericardium. Single-layer cubic epithelium sweeps part of the renal tubules, the ducts of many glands and small bronchi. Single-layer prismatic epithelium has a mucous membrane of the stomach, thin and large intestines, uterus, uterine pipes, a gallbladder, a series of liver ducts, pancreas, parts

kidney tubes. In the organs where suction processes occur, epithelial cells have a suction unit consisting of a large number of microvascular. Single-layer multi-row fixed epithelium wreens up air paths: nasal cavity, nasopharynk, larynx, trachea, bronchi, etc.

Multilayer flat, non-philitating epithelium covers outside the corneal of the eye and the mucous membrane of the oral cavity and the esophagus. The alternate flat ornamental epithelium forms the surface layer of the kří and is called the epidermis. The transitional epithelium is typical for the urinary organs: pellets of the kidneys, ureters, bladder, the walls of which are susceptible to significant stretching when urine filling.

Exocrine glands allocate their secret in the cavity of the internal organs or to the surface of the body. They, as a rule, have output ducts. Endocrine glands do not have ducts and secrete secrets (hormones) in blood or lymph.

Epithelial tissue (synonym for epithelium) is a fabric, lining the surface of the skin, cornea of \u200b\u200bthe eye, serous shells, the inner surface of the hollow organs of the digestive, respiratory and urogenital system, as well as the forming gland.

Epithelial tissue is characterized by a high regeneration capacity. Different types of epithelial tissue perform different functions and therefore have a different structure. Thus, the epithelial tissue that performs mainly the function of protection and separation from the external environment (skin epithelium) is always multi-layered, and some kinds are equipped with a stratum and participate in protein metabolism. Epithelial tissue, in which the function of external exchange is the leading (intestinal epithelium), always single layer; It has microwaves (brush kaym), which increases the suction surface of the cell. This epithelium is also a ferrous, highlighting a special secret necessary to protect epithelial tissue and chemical treatment of substances penetrating through it. The renal and nominal types of epithelial tissue perform the functions of suction, the formation of secrets; They are also single-layer, one of them is equipped with a brush border, the other has pronounced recesses, on the basal surface. In addition, some types of epithelial tissue have permanent narrow intercellular slits (renal epithelium) or periodically arising large intercellular holes - shomats (non-epithelium), which contributes to processes and suction.

Epithelial fabric (epithelium, from Greek. Epi - on, over and theele - nipples) - border tissue, lining the surface of the skin, cornea of \u200b\u200bthe eye, serous shells, the inner surface of hollow organs of digestive, respiratory and urogenital systems (stomach, trachea, uterus, etc. .). Most glands of epithelial origin.

The border position of the epithelial tissue is due to its participation in metabolic processes: gas exchange through the epithelium alveoli of the lungs; The absorption of nutrients from the intestinal lumen in blood and lymph, the separation of urine through the kidney epithelium, etc. In addition, the epithelial tissue also performs a protective function, preventing the tissues from damaging effects.

Unlike other tissues, the epithelial tissue develops from all three germ sheets (see). From Etoderma - skin epithelium, oral cavity, most of the esophagus, cornea of \u200b\u200bthe eye; from Entoderma - the epithelium of the gastrointestinal tract; From the Mesoderm - the epithelium of the organs of the urogenital system and serous shells - mesothelium. Epithelial tissue occurs in the early stages of embryonic development. Entering the placenta, the epithelium is involved in the exchange between the mother and the fruit. Taking into account the peculiarities of the origin of epithelial tissue, it is proposed to divide it onto the skin, intestinal, kidney, nominal epithelium (mesothelium, sex epithelium) and ependimoglyal (epithelium of some senses).

All types of epithelial tissue are characterized by a number of common features: epithelium cells together form a solid reservoir located on a basal membrane, through which the epithelial tissue is powered by The epithelial tissue has a high regenerator capacity, and the integrity of the damaged reservoir is usually restored; The cells of the epithelial tissue are characterized by the polarity of the structure due to the differences in the basal (located closer to the basal membrane) and the opposite - the apical parts of the cellular body.

Within the reservoir, the bonding of neighboring cells is often carried out with the help of the premosomom - special multiple structures of submicroscopic sizes consisting of two half, each of which in the form of a thickening is located on adjacent surfaces of neighboring cells. The slitual gap between halves is filled with substance, apparently of carbohydrate nature. If the intercellular gaps are expanded, then the despair are at the ends of the emotions of the cytoplasm of contacting cells to each other. Each pair of such empty has a view of an intercellular bridge with light microscopy. In the epithelium of the small intestine, the gaps between adjacent cells are closed from the surface due to the merger in these places of cell membranes. Such fusion places were described as closing plates. In other cases, these special structures are absent, neighboring cells are in contact with their smooth or winding surfaces. Sometimes the edges of the cells are tiled over each other. The basal membrane between the epithelium and the fabric is formed by a substance rich in mucopolysaccharides and containing a network of thin fibrils.

The cells of the epithelial tissue are covered with a plasma shell surface and contain organides in the cytoplasm. In cells through which exchange products are intensified, the plasma shell of the basal part of the cell body is folded. On the surface of a series of cells, the epithelium of the cytoplasm forms small, traversed the dudder to grow - microwaves. They are especially many on the apical surface of the epithelium of the small intestine and the main departments of the convinced kidney tube. Here, microvils are located in parallel to each other and in the aggregate light-pointer have a strip (intestinal epithelial cuticle and brush kaym in the kidney). Microwaves increase the suction surface of the cells. In addition, a number of enzymes were found in the microwaves of the cuticle and brush kayma.

On the surface of the epithelium of some organs (trachea, bronchi, etc.) there are cilia. Such an epithelium, which has on its surface of the cilia, was called fame. Due to the movement of cilia from the respiratory organs, dust particles are removed, the directional current of the fluid is created in the ovitsa. The basis of the cilia, as a rule, is 2 central and 9 paired peripheral fibrils associated with derivative centrioles - basal tales. Similar structure have firing spermatozoa flavors.

With a pronounced polarity of the epithelium in the basal part of the cell, the kernel is located above it - mitochondria, the Golgi complex, centrioli. The endoplasmic network and the Golges complex are especially developed in secreting cells. In the cytoplasm of the epithelium experiencing a large mechanical load, a system of special threads is developed - tonofibrils, creating as it were for a frame that prevents cell deformation.

The form of epithelium cells is divided into cylindrical, cubic and flat, and by the location of the cells - on the single-layer and multilayer. In one-layer epithelium, all cells lie on the basal membrane. If the cells have the same shape, i.e. is isomorphic, then their kernels are located at one level (in one row) is a single-row epithelium. If the cells of different shape alternate in one-layer epithelium, their kernels are visible at different levels - a multi-row, anisorphic epithelium.

In the multilayer epithelium on the basement membrane, only the cells of the lower layer are located; The remaining layers are located above it, with the shape of the cell of different layers of unequal. The multi-layer epithelium is different in the form and state of the cells of the outer layer: a multilayer flat epithelium, a multi-layered oroging (with layers of burned scales on the surface).

A special type of multilayer epithelium is the transitional epithelium of the organs of the excretory system. Its structure varies depending on the stretching of the wall of the organ. In the stretched bladder, the transitional epithelium is thinned and consists of two layers of cells - basal and coating. With the reduction of the epithelium organ sharply thickens, the shape of the base layer cells becomes a polymorphic, and their kernels are located at different levels.

Cooking cells become pear and enjoy each other.

Epithelial fabric is one of the main body tissues. It covers the whole body, as well as the external and inner surface of its organs. Depending on the body section, the epithelial tissue performs different functions, so its shape and structure can also be different.

Functions

The coating epithelium (for example, the epidermis) performs, first of all, the protective function. Some coating epitheliums (for example, guts, peritoneum or pleura) ensure the absorption of the fluid, since their cells are capable of capturing the components of food and other substances. Irony epithelium is the main mass of the glands, the epithelial cells of which are involved in the formation and separation of substances. And sensitive cells, called olfactory epithelium, perceive smells and transmit them to the brain.

Epithelial tissue is formed by three germinal sheets. From the ectoderm, the epitheliums of the skin, mucous membranes, mouth, the posterior hole, the thread of the vagina, etc. are formed. The tissues of the digestive tract, liver, pancreas, the bladder, the thyroid gland, the inner ear and the part of the urethoid canal are formed from the Entoderma. From the Mesoderm, the epitheliums of the kidneys, peritoneum, germ glands and the inner walls of blood vessels are formed.

Structure

By virtue of the variety of functions performed, the structure and appearance of epithelial tissue can be different. The thickness of the upper cell layer and the cell form differ flat, cubic and cylindrical epithelium. In addition, tissues are divided into single-layer and multi-layered.

Flat epithelium

The layer consists of flat cells (hence its name). Single-layer flat epithelium sweeps internal body cavities (pleura, pericardium, abdominal cavity), internal walls of blood vessels, alveoli lungs and heart muscle. Multilayer flat epithelium covers those parts of the body that are exposed to a large load, i.e. Outer layer of skin, mucous membranes, conjunctiva. It consists of several cell layers, there is a damage and non-coaling.

Cubic epithelium

His cells in shape resemble cubes. This fabric is available in the area of \u200b\u200bthe output ducts of glands. Large output gonduct glands are single-layer or multilayer cubic epithelium.

Cylindrical epithelium

This layer is named in the form of the components of its cells. Such a tissue wore most of the digestive channel, the uterine tubes and the uterus. The surface of the cylindrical epithelium may increase in size due to shimmering cilia-cilly-cilios located on it. With the help of these cilias from the respiratory tract, foreign bodies and highlights are pushed.

Transitional epithelium

Transition - a special form of a multilayer epithelium, formed by large cells that have one or more nuclei that are strongly stretched. It covers the stripe organs that can change their volume, for example, the bladder or the front separation of the urethra.

Fabric is a combination of cells and an intercellular substance. It has common signs of the structure and performs the same functions. In the body four types of fabrics: epithelial, nervous, muscle and coupling.

The structure of epithelial and animals is due primarily to its localization. The epithelial fabric is a borderline layer of cells, lining the cover of the body, mucous membranes of internal organs and cavities. Also, many glands in the body are formed by the epithelium.

general characteristics

The structure of epithelial tissue has a number of features inherent in the epithelium. The main feature is that the fabric itself has the form of a continuous layer of cells that fit tightly to each other.

Epithelium, lining all surfaces in the body, has the form of a formation, whereas in the liver, pancreas, thyroid, salivary and other glands, it is a cluster of cells. In the first case, it is located on top of the basal membrane separating the epithelium from the connective tissue. But there are exceptions when the structure of epithelial and connective tissue is considered in the context of their interaction. In particular, in the lymph system there is an alternation of cells of epithelial and connective tissue. This type of epithelium is called atypical.

High regeneration ability is another feature of the epithelium.

The cells of this tissue are polar, which is due to the difference in the basal and apical parts of the cellular center.

The structure of epithelial tissue is largely due to its border position, which, in turn, makes the epithelium an important link in the exchange processes. This fabric is involved in the suction of nutrients from the intestine to blood and lymph, in the selection of urine through the epithelium of the kidneys, etc. It is also impossible to forget about the protective function, which consists in protecting tissues from damaging effects.

The structure of the substance forming the basal membrane shows that it contains a large amount of mucopolysaccharides, and there is also a network of thin fibrils.

How is the epithelial tissue laid?

The features of the structure of the epithelial tissue of animals and the person are largely dictated by the fact that its development is carried out from all three this feature inherent in only this type of tissue. Etoderma gives rise to the epithelium of the skin, the oral cavity, a significant part of the esophagus, the cornea of \u200b\u200bthe eye; Entoderma - the epithelium of the gastrointestinal tract; And Mesoderm - the epithelium of the urinary organs and serous shells.

In embryonic development begins to form in the earliest stages. Since the placenta is a sufficient number of epithelial tissue, it is a participant in the metabolism between the mother and the embryo.

Maintenance of the integrity of the cells of the epithelium

The interaction of neighboring cells in the formation is possible due to the presence of despair. These are special multiple submicroscopic structures, which consist of two halves. Each of them, thickening in certain places, occupies adjacent surfaces of neighboring cells. In the sliding gap between the halves, the substance of carbohydrate origin is located.

In cases where the intercellular gaps are wide, the desplaomoms are located at the ends of the dissipation of cytoplasm on contacting cells. If we consider a pair of these empty under the microscope, you can find that they have the kind of an intercellular bridge.

In the small intestine, the integrity of the reservoir is maintained due to the merger of cell shells of neighboring cells in places of contact. Such places are often referred to as closing plates.

There are other cases when there are no special structures providing integrity. Then the contact of the neighboring cells is carried out due to the contact of smooth or winding cell surfaces. The edges of the cells can be tiled over each other.

Epithelial tissue

The features of epithelial tissue cells include the presence of plasma shell on their surface.

In cells involved in the allocation of the exchange products, in the plasma shell of the basal part of the cellular body, folded is observed.

Epitheliocytes are so called the cells in the science forming epithelial fabrics. Features of the structure, the epithelialocyte functions are in close relationship. So, in form they are divided into flat, cubic and columnar. Euchromatin prevails in the kernel, due to which it has a bright color. The kernel is quite large, its form coincides with the form of the cell.

The pronounced polarity causes the location of the kernel in the basal part, the mitochondria complex, the Golges and Centriol complex is located above it. In the cells that perform a secretory function, the endoplasmic network and the Golgi complex are especially well developed. Epithelium, experiencing a large mechanical load, in its cells has a system of special threads - Tonophybrils, which create a barrier, designed to protect cells from deformation.

Microwave

Some cells, or rather their cytoplasm, on the surface can form the smallest, directed into the outer side, the growing microvilles. The largest clusters are available on the apicial surface of the epithelium in the small intestine and the main departments of the convinced kidney tube. Due to the parallel location of the microorus, the intestinal epithelial cuticle and the brush kaym of the kidneys are formed, which can be considered under an optical microscope. In addition, microvils in these places contain a number of enzymes.

Classification

The features of the structure of epithelial tissues of different localization allow them to classify them in several features.

Depending on the shape of the epithelium cells, there may be cylindrical, cubic and flat, and depending on the location of the cells - one-layer and multilayer.

Also isolated iron epithelium, performing a secretory function in the body.

Single-layer epithelium

The name of the single-layer epithelium speaks for itself: in it, all cells are located on the basal membrane in one layer. If at the same time the shape of all cells is the same (i.e. they are isomorphic), and are on the same level, they are talking about the single-row epithelium. And if there is an alternation of cells of various shapes in one-layer epithelium, their kernels are located at different levels, then this is a multi-row or anisorphic epithelium.

Multilayer epithelium

In a multi-layer epithelium, only the lower layer comes into contact with the basal membrane, while other layers are above it. In the form of a cell of different layers differ. The structure of the epithelial tissue of this type allows you to select several types of multilayer epithelium, depending on the shape and state of the multilayer flat, multilayer oroging (there are damaged flakes on the surface), a multi-layer non-illuminating.

There is also the so-called transitional epithelium, lining the organs of the excretory system. Depending on whether or stretched, the fabric acquires a different appearance. Thus, when tensile the bladder, the epithelium is in the thinned state and forms two layers of cells - basal and coating. And when the bladder is in a compressed (abbreviated) form, the epithelial cloth sharply thickens, the cells of the basal layer become polymorphic and their kernels are at various levels. Pokroval cells acquire a pear shape and lay down on each other.

Histogenetic classification of epithelium

The structure of the epithelial tissue of animals and man often becomes the subject of scientific and medical research. In these cases, more often than others use histogenetic classification developed by Academician N. G. Chlopin. According to it, five types of epithelium stands out. The criterion is the fact that the concerns developed fabric in embryogenesis.

1. The epidermal type, the beginning of which was given ectoderma and a precrowdal plate.

2. Enterodermal type, the development of which occurred from the intestinal entoderma.

3. Corolorfrodermal type, developed from a nuclear chipping and nephrotomom.

4. Anchodermal type, the development of which began from a segment of mesenchym, forming vascular endothelium, which is called an anchioblast.

5. Empdendimoglyal type, the beginning of which has given a nervous tube.

Features of the structure of epithelial tissues forming glands

Irony epithelium performs a secretory function. This type of fabric is a cluster of ferrous (secretory) cells, which are called granulocytes. Their function lies in the implementation of synthesis, as well as the separation of specific substances - secrets.

It is due to secretion that the body is able to perform many important functions. The glands allocate secrets on the surface of the skin and mucous membranes, within cavities of a number of internal organs, as well as in blood and in lymph. In the first case, we are talking about exocrine, and in the second - about endocrine secretion.

Exocrine secretion allows milk to produce (in the female body), gastric and intestinal juice, saliva, bile, sweat and skin fat. The secrets of the endocrine glands are hormones performing humoral regulation in the body.

The structure of the epithelial tissue of this type may be different due to the fact that granulocytes can take different shapes. It depends on the secretion phase.

Both types of glands (endocrine and exocrine) can consist of one cell (single-cell) or from a variety of cells (multicellular).