Structural elements of cartilage. Cartilage tissue Location of cartilage in the body n

13.10.2019

Chondroblasts - poorly differentiated young cells capable of proliferation and synthesis of intercellular substance.

Form- irregular, elongated, flattened.

Development- from semi-stem cells (perichondroblast), which originate from stem cells. Stem cells, semi-stem cells, chondroblasts and chondrocytes form a differon (histogenetic series).

Cytoplasm- contains a well-developed endoplasmic reticulum (granular and agranular) and elements of the Golgi complex, a lot of RNA. Stained basophilic.

During cartilage development, chondroblasts transform into chondrocytes. Chondroblasts carry out peripheral (appositional) growth of cartilage.

Chondrocytes - the main cells of cartilage tissue.

Form- oval, round or polygonal.

Localization- located in special cavities of the intercellular substance (lacunae). These groups of cells are called (isogenic).

Happening- due to the division of one cell. There are three types of chondrocytes in the isogenic group:

I the cell type predominates in young developing cartilage; division is often observed in these cells, which allows them to be considered as a source of reproduction of isogenic groups.

Characteristic for these cells is the presence of a high nuclear-cytoplasmic index.

Cytoplasm- has well-developed vacuolar elements, lamellar complex, mitochondria and free ribosomes.

II cell type - characterized by a decrease in the nuclear-cytoplasmic index, a weakening of DNA synthesis, but RNA synthesis is increased, the granular endoplasmic reticulum and the Golgi complex are intensively developed, ensuring the formation and secretion of glycosaminoglycans and proteoglycans into the intercellular substance. The cytolemma and karyolemma are usually tortuous.

III type of chondrocyte. These cells are characterized by a low nuclear-cytoplasmic index, strong development and ordered arrangement of the granular endoplasmic reticulum. This type of cell retains the ability to form and secrete protein, while reducing the synthesis of glycosaminoglycans.

Intercellular substance of cartilage is represented by an organic component - proteins, lipids, glycosaminoglycans and proteoglycans. The concentration of proteoglycans in this tissue is the highest. Fibrillar proteins, mainly type II collagen, are contained in large quantities.

Fiber orientation determined by the direction of the field lines.

The layer of intercellular substance adjacent to the cell cavity and forming its wall is characterized by high light refraction and contains a felt-like network of fibrils. It is sometimes called the cartilage cell capsule.

Hyaline cartilage tissue.

Localization- in the wall of the trachea, bronchi, at the junction of the ribs and sternum, articular surfaces and in the metaepiphyseal plates.

Structure. Externally covered with hyaline cartilage tissue perichondrium(perichondrium).

The perichondrium consists of two layers: 1) outer; 2) internal;

*External - formed by fibrous connective tissue with blood vessels.

*Internal - formed mainly by cells prechondroblasts and chondroblasts.

Under the perichondrium in the superficial layer of the cartilage itself there are young chondrocytes spindle-shaped, the long axis of which is directed along the surface of the cartilage.

In the deeper layers, chondrocytes acquire an oval and round shape, arranged in several groups, forming isogenic groups. Young chondrocytes and isogenic groups are surrounded by chondromucoid and collagen fibers (type II collagen).

· However, not all hyaline cartilage has the same structure.

Hyaline cartilage of the articular surface does not have perichondrium on the surface facing the inside of the joint. Articular cartilage consists of three zones that are not clearly defined: a) external; b) average; c) deep;

In the outer area small flattened, unspecialized cells are located.

In average- the cells are larger, oval, round, arranged in the form of columns perpendicular to the surface.

Deep zone consists of calcified cartilage; Only in this zone were blood vessels found.

The basis of the musculoskeletal system is cartilage tissue. It is also part of the facial structures, becoming the site of attachment of muscles and ligaments. The histology of cartilage is represented by a small number of cellular structures, fibrous formations and nutrients. This ensures sufficient shock-absorbing function.

What does it represent?

Cartilage is a type of connective tissue. The structural features are increased elasticity and density, due to which it is able to perform a supporting and mechanical function. Articular cartilage consists of cells called chondrocytes and a ground substance containing fibers that provide the elasticity of the cartilage. Cells in the thickness of these structures form groups or are located separately. The location is usually near bones.

Types of cartilage

Depending on the characteristics of the structure and localization in the human body, there is the following classification of cartilage tissue:

Hyaline cartilage contains chondrocytes arranged in the form of rosettes. The intercellular substance is larger in volume than the fibrous substance, and the threads are represented only by collagen.
Elastic cartilage contains two types of fibers - collagen and elastic, and the cells are arranged in columns or columns. This type of fabric has less density and transparency, but has sufficient elasticity. This matter makes up the cartilage of the face, as well as the structures of the secondary formations in the bronchi.
Fibrous cartilage is a connective tissue that functions as strong shock-absorbing elements and contains a significant amount of fibers. The localization of the fibrous substance is throughout the musculoskeletal system.

Properties and structural features of cartilage tissue

The histological specimen shows that the tissue cells are loosely located, surrounded by an abundance of intercellular substance.

All types of cartilage tissue are capable of absorbing and counteracting the compressive forces that arise during movement and load. This ensures an even distribution of gravity and reduces the load on the bone, which stops its destruction. Skeletal areas where friction processes constantly occur are also covered with cartilage, which helps protect their surfaces from excessive wear. The histology of this type of tissue differs from other structures in the large amount of intercellular substance, and the cells are loosely located in it, form clusters or are found separately. The main substance of the cartilage structure is involved in the processes of carbohydrate metabolism in the body.

This type of material in the human body, like others, contains cells and intercellular substance of cartilage. The peculiarity is a small number of cellular structures, which ensures the properties of the tissue. Mature cartilage is a loose structure. Elastic and collagen fibers perform a supporting function in it. The general structural plan includes only 20% of cells, and the rest is fibers and amorphous matter. This is due to the fact that, due to dynamic load, the vascular bed of the tissue is weakly expressed and therefore it is forced to be nourished by the main substance of the cartilaginous tissue. In addition, the amount of moisture contained in it performs shock-absorbing functions, smoothly relieving tension in bone tissue.

What are they made of?

The trachea and bronchi are composed of hyaline cartilage.

Each type of cartilage has unique properties due to differences in location. The structure of hyaline cartilage differs from the rest in the smaller number of fibers and greater filling with amorphous substance. In this regard, it is not able to withstand heavy loads, since its tissues are destroyed by the friction of bones, however, it has a rather dense and solid structure. Therefore, it is characteristic that the bronchi, trachea and larynx consist of this type of cartilage. Skeletal and musculoskeletal structures are formed predominantly by fibrous matter. Its variety includes part of the ligaments connected to hyaline cartilage. The elastic structure occupies an intermediate location relative to these two tissues.

Cellular composition

Chondrocytes do not have a clear and ordered structure, but are more often located completely chaotically. Sometimes their clusters resemble islands with large areas of absence of cellular elements. In this case, a mature type of cell and a young one, called chondroblasts, are located together. They are formed by the perichondrium and have interstitial growth, and during their development they produce various substances.

Chondrocytes are the source of components of the intercellular space, it is thanks to them that there is such a chemical table of elements in the composition of the amorphous substance:

Hyaluronic acid is contained in an amorphous substance.

proteins;
glycosaminoglycans;
proteoglycans;
hyaluronic acid.

During the embryonic period, most bones are hyaline tissue.

The structure of the intercellular substance

It consists of two parts - fibers and an amorphous substance. In this case, fibrillar structures are located chaotically in the tissue. The histology of cartilage is influenced by the production of chemical substances by its cells that are responsible for density, transparency and elasticity. The structural features of hyaline cartilage consist in the presence of only collagen fibers in its composition. If an insufficient amount of hyaluronic acid is released, it destroys tissues due to degenerative processes in them.

Blood flow and nerves

The structures of cartilage tissue do not have nerve endings. Pain reactions in them are represented only with the help of bone elements, while the cartilage will already be destroyed. This causes a large number of untreated diseases of this tissue. There are few nerve fibers on the surface of the perichondrium. The blood supply is poor and the vessels do not penetrate deep into the cartilage. Therefore, nutrients enter the cells through the ground substance.

Functions of structures

The auricle is formed from this tissue.

Cartilage is the connecting part of the human musculoskeletal system, but is sometimes found in other parts of the body. The histogenesis of cartilage tissue goes through several stages of development, due to which it is able to provide support while at the same time being completely elastic. They are also part of the external formations of the body such as the cartilage of the nose and ears. Ligaments and tendons are attached to them to the bone.

Age-related changes and diseases

The structure of cartilage tissue changes with age. The reasons for this lie in the insufficient supply of nutrients to it; as a result of disturbances in trophism, diseases arise that can destroy fibrous structures and cause cell degeneration. A young body has a much larger supply of fluid, so these cells have sufficient nutrition. However, age-related changes cause “drying out” and ossification. Inflammation due to bacterial or viral agents can cause cartilage degeneration. Such changes are called “chondrosis”. At the same time, it becomes less smooth and is unable to perform its functions, as its nature changes.

Signs that the tissue has been destroyed are visible during histology analysis.

How to eliminate inflammatory and age-related changes?

To cure cartilage, drugs are used that can restore the independent development of cartilage tissue. These include chondroprotectors, vitamins and products that contain hyaluronic acid. A proper diet with a sufficient amount of protein is important, because it is a stimulator of body regeneration. It is indicated to keep the body in good shape, because excess body weight and insufficient physical activity cause destruction of structures.

They perform mechanical, support, and protective functions. They contain elastic, dense intercellular substance. The water content is up to 70-80%, minerals up to 4-7%, organic matter up to 10-15%, and they are dominated by proteins, carbohydrates and very few lipids. They contain cells and intercellular substance. The cellular composition of all types of cartilage tissue is the same and includes chondroblasts - poorly differentiated, flattened cells with basophilic cytoplasm; they are capable of proliferating and producing intercellular substance. Chondroblasts differentiate into young chondrocytes and acquire an oval shape. They retain the ability to proliferate and produce intercellular substance. The small ones then differentiate into larger, round mature chondrocytes. They lose the ability to proliferate and produce intercellular substance. Mature chondrocytes deep in the cartilage accumulate in one cavity and are called isogenic groups of cells.

Cartilaginous tissues differ in the structure of the intercellular substance and fibrous structures. There are hyaline, elastic and fibrous cartilage tissues. They participate in the formation of cartilage and form hyaline, elastic and fibrous cartilage.

Hyaline cartilage lines the articular surfaces, is located in the area where the ribs join the sternum and in the wall of the airways. The outside is covered with perichondrium - perichondrium, which contains blood vessels. E, the peripheral part consists of denser connective tissue, and the internal part is loose, containing fibroblasts and chondroblasts. Chondroblasts produce and secrete intercellular substance and cause appositional growth of cartilage. In the peripheral part of the cartilage itself there are young chondrocytes. They proliferate, produce and secrete chondromitin sulfates + proteoglycans, allowing cartilage to grow from the inside.

In the middle part of the cartilage there are mature chondrocytes and isogenic groups of cells. Between the cells there is intercellular substance. It contains ground substance and collagen fibers. There are no vessels; it feeds diffusely from the vessels of the periosteum. In young cartilage, the intercellular substance is oxyphilic and gradually becomes basophilic. With age, starting from the central part, calcium salts are deposited in the cartilage, the cartilage calcifies, becomes brittle and brittle.

Elastic cartilage - forms the basis of the auricle, in the wall of the airways. It is similar in structure to hyaline cartilage, but contains elastic rather than collagen fibers, and normally it never calcifies.

Fibrous cartilage - it is located in the transition zone of ligaments, tendons with bone tissue, in the area where the bones are covered with hyaline cartilage and in the area of intervertebral joints. In it, coarse bundles of collagen fibers run along the tension axis, being a continuation of the tendon threads. Fibrous cartilage in the area of attachment to the bone is more similar to hyaline cartilage, and in the area of transition to the tendon it is more like a tendon.

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Cartilage tissue: functions, structural features, types, restoration

Nerve fibers are also localized in the perichondrium, from where individual branches of the soft nerve fibers can penetrate into the cartilage tissue.

Hyaline cartilage
Elastic cartilage
Fibrous cartilage

Functions of bone tissue:

1) supporting;

2) mechanical;

osteocytes. These are process-shaped cells with a large nucleus and weakly expressed cytoplasm (nuclear-type cells). Cell bodies are localized in bone cavities (lacunae), and processes are located in bone tubules. Numerous bone tubules, anastomosing with each other, penetrate the bone tissue, communicating with the perivascular space, forming a drainage system of the bone tissue. This drainage system contains tissue fluid, through which metabolism is ensured not only between cells and tissue fluid, but also in the intercellular substance.

Osteoblasts

Osteoclasts

Intercellular substance

Bone

Classification of bone tissue

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The relative position of the lines.

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Cartilage tissue - structure, types, location in the body.

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Cartilaginous tissue (textus cartilaginus) forms articular cartilage, intervertebral discs, cartilage of the larynx, trachea, bronchi, and external nose. Cartilage tissue consists of cartilage cells (chondroblasts and chondrocytes) and dense, elastic intercellular substance.

Cartilage tissue contains about 70-80% water, 10-15% organic substances, 4-7% salts. About 50-70% of the dry matter of cartilage tissue is collagen. The intercellular substance (matrix), produced by cartilage cells, consists of complex compounds that include proteoglycans. hyaluronic acid, glycosaminoglycan molecules. Cartilage tissue contains two types of cells: chondroblasts (from the Greek chondros - cartilage) and chondrocytes.

Chondroblasts are young round or ovoid cells capable of mitotic division. They produce components of the intercellular substance of cartilage: proteoglycans, glycoproteins, collagen, elastin. The cytolemma of chondroblasts forms many microvilli. The cytoplasm is rich in RNA, a well-developed endoplasmic reticulum (granular and non-granular), Golgi complex, mitochondria, lysosomes, and glycogen granules. The chondroblast nucleus, rich in active chromatin, has 1-2 nucleoli.

Chondrocytes are mature large cells of cartilage tissue. They are round, oval or polygonal, with processes and developed organelles. Chondrocytes are located in cavities - lacunae, surrounded by intercellular substance. If there is one cell in a lacuna, then such a lacuna is called primary. Most often, the cells are located in the form of isogenic groups (2-3 cells) occupying the cavity of the secondary lacuna. The walls of the lacuna consist of two layers: the outer layer, formed by collagen fibers, and the inner layer, consisting of aggregates of proteoglycans that come into contact with the glycocalyx of cartilage cells.

The structural and functional unit of cartilage is the chondrone, formed by a cell or an isogenic group of cells, a pericellular matrix and a lacuna capsule.

Nutrition of cartilage tissue occurs through the diffusion of substances from the blood vessels of the perichondrium. Nutrients penetrate into the tissue of articular cartilage from the synovial fluid or from the vessels of the adjacent bone. Nerve fibers are also localized in the perichondrium, from where individual branches of the soft nerve fibers can penetrate into the cartilage tissue.

In accordance with the structural features of cartilage tissue, three types of cartilage are distinguished: hyaline, fibrous and elastic cartilage.

Hyaline cartilage, from which in humans the cartilage of the respiratory tract, thoracic ends of the ribs and articular surfaces of bones is formed. In a light microscope, its main substance appears homogeneous. Cartilage cells or isogenic groups of them are surrounded by an oxyphilic capsule. In differentiated areas of cartilage, a basophilic zone adjacent to the capsule and an oxyphilic zone located outside it are distinguished; Collectively, these zones form the cellular territory, or chondrin ball. The complex of chondrocytes with the chondrinic ball is usually taken to be the functional unit of cartilage tissue - the chondrone. The main substance between chondrons is called interterritorial spaces.
Elastic cartilage(synonym: reticular, elastic) differs from hyaline in the presence of branching networks of elastic fibers in the ground substance. The cartilage of the auricle, epiglottis, Wrisberg and Santorini cartilages of the larynx are built from it.
Fibrous cartilage(synonym for connective tissue) is located in the places of transition of dense fibrous connective tissue into hyaline cartilage and differs from the latter in the presence of real collagen fibers in the main substance.

7. Bone tissue - location, structure, functions

Bone tissue is a type of connective tissue and consists of cells and intercellular substance, which contains a large amount of mineral salts, mainly calcium phosphate. Minerals make up 70% of bone tissue, organic substances – 30%.

Functions of bone tissue:

1) supporting;

2) mechanical;

3) protective (mechanical protection);

4) participation in the mineral metabolism of the body (calcium and phosphorus depot).

Functions of cartilage tissue

Cell bodies are localized in bone cavities (lacunae), and processes are located in bone tubules. Numerous bone tubules, anastomosing with each other, penetrate the bone tissue, communicating with the perivascular space, forming a drainage system of the bone tissue. This drainage system contains tissue fluid, through which metabolism is ensured not only between cells and tissue fluid, but also in the intercellular substance.

Osteocytes are the definitive form of cells and do not divide. They are formed from osteoblasts.

Osteoblasts found only in developing bone tissue. In formed bone tissue they are usually contained in an inactive form in the periosteum. In developing bone tissue, osteoblasts cover the periphery of each bone plate, tightly adjacent to each other.

The shape of these cells can be cubic, prismatic and angular. The cytoplasm of osteoblasts contains a well-developed endoplasmic reticulum, a lamellar Golgi complex, and many mitochondria, which indicates the high synthetic activity of these cells. Osteoblasts synthesize collagen and glycosaminoglycans, which are then released into the intercellular space. Due to these components, the organic matrix of bone tissue is formed.

These cells provide mineralization of the intercellular substance by secreting calcium salts. Gradually releasing intercellular substance, they become immured and turn into osteocytes. In this case, intracellular organelles are significantly reduced, synthetic and secretory activity is reduced, and the functional activity characteristic of osteocytes is preserved. Osteoblasts, localized in the cambial layer of the periosteum, are in an inactive state, and their synthetic and transport organelles are poorly developed. When these cells are irritated (in case of injuries, bone fractures, etc.), granular EPS and lamellar complex quickly develop in the cytoplasm, active synthesis and release of collagen and glycosaminoglycans occurs, the formation of an organic matrix (bone callus), and then the formation of definitive bone fabrics. In this way, due to the activity of osteoblasts of the periosteum, bone regeneration occurs when they are damaged.

Osteoclasts– bone-destructive cells are absent in formed bone tissue, but are contained in the periosteum and in places of destruction and restructuring of bone tissue. Since local processes of bone tissue restructuring are continuously carried out during ontogenesis, osteoclasts are also necessarily present in these places. During the process of embryonic osteohistogenesis, these cells play a very important role and are present in large numbers. Osteoclasts have a characteristic morphology: these cells are multinucleated (3 - 5 or more nuclei), have a fairly large size (about 90 microns) and a characteristic shape - oval, but the part of the cell adjacent to the bone tissue is flat. In the flat part, two zones can be distinguished: the central (corrugated part, containing numerous folds and processes, and the peripheral part (transparent) in close contact with the bone tissue. In the cytoplasm of the cell, under the nuclei, there are numerous lysosomes and vacuoles of various sizes.

The functional activity of the osteoclast is manifested as follows: in the central (corrugated) zone of the cell base, carbonic acid and proteolytic enzymes are released from the cytoplasm. The released carbonic acid causes demineralization of bone tissue, and proteolytic enzymes destroy the organic matrix of the intercellular substance. Fragments of collagen fibers are phagocytosed by osteoclasts and destroyed intracellularly. Through these mechanisms, resorption (destruction) of bone tissue occurs, and therefore osteoclasts are usually localized in the recesses of bone tissue. After the destruction of bone tissue, due to the activity of osteoblasts moving out of the connective tissue of blood vessels, new bone tissue is built.

Intercellular substance bone tissue consists of a basic (amorphous) substance and fibers that contain calcium salts. The fibers consist of collagen and are folded into bundles, which can be arranged in parallel (ordered) or disorderly, on the basis of which the histological classification of bone tissue is based. The main substance of bone tissue, like other types of connective tissues, consists of glycosaminergic and proteoglycans.

Bone tissue contains less chondroitinsulfuric acids, but more citric acids and others, which form complexes with calcium salts. During the development of bone tissue, an organic matrix is first formed - the main substance and collagen fibers, and then calcium salts are deposited in them. They form crystals - hydroxyapatites, which are deposited both in the amorphous substance and in the fibers. Providing bone strength, calcium phosphate salts are also a depot of calcium and phosphorus in the body. Thus, bone tissue takes part in the mineral metabolism of the body.

When studying bone tissue, the concepts of “bone tissue” and “bone” should also be clearly distinguished.

Bone is an organ whose main structural component is bone tissue.

Classification of bone tissue

There are two types of bone tissue:

1) reticulofibrous (coarse fibrous);

2) lamellar (parallel fibrous).

The classification is based on the nature of the arrangement of collagen fibers. In reticulofibrous bone tissue, the bundles of collagen fibers are thick, tortuous and randomly arranged. In the mineralized intercellular substance, osteocytes are randomly located in the lacunae. Lamellar bone tissue consists of bone plates in which collagen fibers or their bundles are located parallel in each plate, but at right angles to the course of the fibers of adjacent plates. Osteocytes are located between the plates in the lacunae, while their processes pass through the plates in the tubules.

In the human body, bone tissue is presented almost exclusively in the lamellar form. Reticulofibrous bone tissue occurs only as a stage in the development of some bones (parietal, frontal). In adults, it is located in the area of attachment of tendons to bones, as well as at the site of ossified sutures of the skull (sagittal suture, scales of the frontal bone).

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Human cartilaginous connective tissue

One of the types of connective tissue present in the human body is cartilage. Cartilaginous connective tissue is distinguished by its relatively high density and elasticity of the intercellular substance that envelops groups of chondrocytes and individual cells. Cartilage differs from bone tissue (as well as from a number of other tissues) by the complete absence of blood vessels and nerves. The shell of cartilage is the perichondrium, which is also called the perichondrium. Cartilaginous connective tissue (CCT) can act as a rigid skeletal base in some animals or forms elastic parts of the skeleton, covering the edges of bones and forming special shock-absorbing layers (such as intervertebral discs). In a word, the main functions of cartilaginous connective tissue are: supporting and joint-forming functions.

The structure of cartilage tissue

As noted above, cartilaginous tissue consists not only of the cartilage itself, but also of the perichondrium (perichondrium), which in turn includes an inner layer of loose fibrous connective tissue (LFC) and an outer layer of dense fibrous connective tissue (DFCT). The PBST (along with chondrocytes and intercellular substance consisting of fibers, interstitial water and amorphous substance) also includes semi-stem and stem cells, a system of blood vessels, nerves and chondroblasts. The volume of chondrocytes is approximately up to 10% of the total mass of cartilaginous connective tissue. Most of all, CST contains intercellular substance, which is characterized by a rather high hydrophilicity, and accordingly provides the possibility of delivering the necessary nutrients to the cells from the blood capillaries of the perichondrium due to diffusion processes. Cartilage can be glassy (if the intercellular substance is homogeneous), fibrous or mesh.

Chondrocytes

The diversity of chondrocytes that make up cartilaginous connective tissue includes chondroblasts, stem and semi-stem cells, and also includes mature and young chondrocytes. Chondrocytes are derivatives of chondroblasts, and in addition, these are cells that are the only cell populations present in cartilage tissue that are found in lacunae. There are young and mature chondrocytes. The former are in many ways identical to chondroblasts. They have an oblong shape, a fairly large Golgi apparatus, and in addition they can produce glycoproteins and protein for elastic and collagen fibers. Mature chondrocyte cells are oval in shape and less capable of synthesis when compared with young chondrocytes. Chondrocytes can divide and form separate cell groups framed by a single capsule. In vitreous cartilage, cell groups of up to 12 cells each may be present, but in other types of cartilage tissue, isogenic groups usually contain fewer cells.

Cartilage tissue: classification and histogenesis

Cartilaginous connective tissue develops not only at the embryonic level, but also in adults (tissue regeneration). During the development of cartilage, the so-called cartilaginous differential is formed, in which stem and semi-stem cells, and then chondroblasts and chondrocytes, successively replace each other. At the initial stage of cartilaginous embryogenesis, a small chondrogenic island is formed. Next, differentiation of chondroblasts occurs with the subsequent appearance of cartilage matrix and fibers. At the final stage of embryogenesis, the cartilaginous anlage experiences interstitial or appositional growth.

Cartilage tissue

In the first, the tissue increases from the inside (characteristic of both the embryonic period and regeneration processes), and in the second, the tissue is layered with the supply of chondroblasts acting in the perichondrium.

Regeneration and age-related changes

Cartilage is restored due to glucosamine and chondroitin sulfate. These components are building materials, thanks to which the elasticity and structure of the joints are restored, arthrosis pain is eliminated, the missing tissue volume is replenished, and the effect of anti-inflammatory drugs is enhanced. Regeneration of cartilage tissue is carried out from the cambial cells of the perichondrium (new cartilaginous layers grow). This process can occur in full force only in childhood, and in adults, cartilage regeneration, unfortunately, does not occur completely. In particular, PVNST is formed in place of the lost cartilage tissue. As a person ages, his fibrous and elastic cartilaginous tissues undergo virtually no changes. At the same time, vitreous cartilage (hyaline cartilage tissue) is prone to transformation into bone tissue and calcification.

Hyaline cartilage tissue

Vitreous tissue is localized mainly in the cartilage of the larynx, nose, bronchi, trachea, ribs, joints, as well as in cartilaginous growth plates present in tubular bones. Hyaline cartilage consists of chondrocytes and, accordingly, intercellular substance, which in turn includes collagen fibers, interstitial water and proteoglycans. Approximately 20-25% of the total volume is collagen fibers, and 5-10% is proteoglycans. The latter do not allow mineralization of vitreous cartilage tissue, and interstitial water, the volume of which reaches 65-85%, promotes depreciation of cartilage and normal metabolism in connective tissue, transporting nutritional components, metabolites and salts. A type of vitreous cartilage is articular cartilage. However, it does not have perichondrium, but receives the necessary nutrients from the synovial fluid. In articular cartilage, the following can be distinguished: acellular zone (superficial), intermediate zone and the so-called deep zone, i.e. zone of interaction of cartilage tissue with bone.

Elastic and fibrous cartilage tissue

Cartilaginous connective tissue, called elastic, is localized in the corniculate, epiglottic, arytenoid (vocal processes) and sphenoid cartilages of the larynx. In addition, elastic cartilaginous tissue is found in the auricle and eustachian tube. This type of tissue is especially needed where the ability of organ areas to change shape and volume, as well as reverse deformation, is required. The composition of elastic tissue includes chondrocytes and an intercellular substance consisting of an amorphous substance (and fibers).

Cartilaginous tissue, called fibrous tissue, is localized in articular menisci and discs, intervertebral discs (in their fibrous rings), in the pubic symphysis (symphysis), in areas of tendon attachment to hyaline cartilage and bones, and also on the surfaces of the sternoclavicular and temporo- mandibular joints. Fibrous cartilaginous connective tissue consists of elongated single chondrocytes and intercellular substance. The latter includes a significant amount of collagen fibers and a fairly small volume of amorphous substance. Typically, collagen fibers are located in the intercellular substance in the form of bundles, arranged in parallel and in an orderly manner.

Types of cartilage tissue and its structure

Cartilage tissue– a type of elastic, dense connective tissue that has a support-mechanical function.

Predominant composition of cartilage tissue: chondrocytes, chondroblasts.

Types of cartilage tissue

— Hyaline (vitreous)– found in the respiratory tract, at the ends of the rib bones and in the joints.

— Fibrous (connective tissue)– serves to connect dense tissue with the fibrous structure of hyaline cartilage.

— Elastic (has a mesh structure)– found in the dense parts of the auricles, larynx (Santorin, Wrisberg, arytenoid, thyroid, cricoid cartilages), epiglottis.

Functions of cartilage tissue

— Ensuring a reliable connection while maintaining mobility between individual elements of the musculoskeletal system (for example, between the bony parts of the spine);

— Involvement in carbohydrate metabolism processes.

Complete regeneration of cartilage tissue observed in humans during childhood. With age, 100% recovery is impossible: damaged cartilage tissue is partially restored, with parallel formation of PVNST at the site of injury.

If there is mechanical damage to the joint or if the destruction is caused by a disease, it is possible to replace the joint with an artificial one.

The natural functions of cartilage tissue are supported by preparations with chondroitin sodium sulfate and glucosamine.

Good therapeutic effect in the initial stages of problems with cartilage tissue, moderate physical exercise and a course of anti-inflammatory treatment with the simultaneous use of drugs with easily digestible calcium are helpful.

The development of problems is caused by:
- injuries,
- infectious diseases,
- excessive physical activity over a long period,
- hypothermia,
- heredity.

The positive effect of anti-inflammatory therapy is observed both when taking the drugs orally and when used externally. The effectiveness of the latter method of exposure is based on the high hydrophilicity of cartilage tissue. Due to this, medications that penetrate the skin quickly end up directly at the site of the disease.

Cartilage tissue contains about 70-80% water, 10-15% organic substances, 4-7% salts. About 50-70% of the dry matter of cartilage tissue is collagen. The intercellular substance (matrix), produced by cartilage cells, consists of complex compounds that include proteoglycans. hyaluronic acid, glycosaminoglycan molecules. There are two types of cells in cartilage tissue: chondroblasts (from the Greek chondros - cartilage) and chondrocytes.

The structural and functional unit of cartilage is the chondrone, formed by a cell or an isogenic group of cells, a pericellular matrix and a lacuna capsule.

In accordance with the structural features of cartilage tissue, three types of cartilage are distinguished: hyaline, fibrous and elastic cartilage.

7. Bone tissue - location, structure, functions

Functions of bone tissue:

1) supporting;

2) mechanical;

3) protective (mechanical protection);

4) participation in the mineral metabolism of the body (calcium and phosphorus depot).

Bone cells - osteoblasts, osteocytes, osteoclasts. The main cells in formed bone tissue are osteocytes. These are process-shaped cells with a large nucleus and weakly expressed cytoplasm (nuclear-type cells). Cell bodies are localized in bone cavities (lacunae), and processes are located in bone tubules. Numerous bone tubules, anastomosing with each other, penetrate the bone tissue, communicating with the perivascular space, forming a drainage system of the bone tissue. This drainage system contains tissue fluid, through which metabolism is ensured not only between cells and tissue fluid, but also in the intercellular substance.

Osteocytes are the definitive form of cells and do not divide. They are formed from osteoblasts.

When studying bone tissue, the concepts of “bone tissue” and “bone” should also be clearly distinguished.

Bone is an organ whose main structural component is bone tissue.

Classification of bone tissue

Bone and cartilage tissue make up the human skeleton. These tissues are assigned a supporting function; at the same time, they protect internal organs and organ systems from unfavorable factors. For the normal functioning of the human body, it is necessary that all the cartilage laid down by nature be in the anatomically correct places, so that the tissues are strong and regenerate as needed. Otherwise, a person is faced with many unpleasant diseases that lower the standard of living, or even completely deprive him of the ability to move independently.

Fabric Features

Tissue, like any other structural elements of the body, is formed from special cells. Cells of cartilage tissue are scientifically called differons. This concept is complex, it includes several types of cells: stem, semi-stem, united within the framework of anatomy into a group of poorly specialized ones - this category is characterized by the ability to actively divide. Chondroblasts are also isolated, that is, cells that can divide, but at the same time are capable of producing intercellular connections. Finally, there are cells whose main task is to create an intermediate substance. Their specialized name is chondrocytes. These cells contain not only fibers of cartilage tissue, the functions of which are to provide stability, but also a basic substance that scientists call amorphous. This compound is capable of binding water, due to which cartilage tissue firmly resists compressive loads. If all the cells of the joint are healthy, it will be elastic and strong.

In science, there are three types of cartilage tissue. To divide into groups, the features of the intercellular connecting component are analyzed. It is customary to talk about the following categories:

elastic;
hyaline;
fibrous.

How about more details?

As is known from anatomy, all types of cartilage tissue have their own characteristic features. Thus, elastic tissue is distinguished by the specific structure of the intercellular substance - it is characterized by a fairly high concentration of collagen fibers. At the same time, such tissue is rich in amorphous substance. At the same time, this fabric contains a high percentage of elastic fibers, which gave it its name. The functions of elastic cartilage tissue are associated with this feature: providing elasticity, flexibility, and persistent resistance to external influences. What other interesting things can anatomy tell you? Where is this type of cartilage tissue located? Usually - in those organs that are naturally designed to bend. For example, the laryngeal cartilages, the nose and conchas of the ears, and the center of the bronchi are made of elastic cartilaginous tissue.

Fiber fabric: some features

At the point where hyaline cartilage begins, fibrous connective tissue ends. Typically this tissue is found in the discs between the vertebrae, as well as at bone junctions where mobility is not important. The structural features of this type of cartilage tissue are directly related to the specifics of its location. Tendons and ligaments at the point of contact with cartilage tissue provoke an actively developed system of collagen fibers. A special feature of this tissue is the presence of cartilage cells (instead of fibroblasts). These cells form isogenic groups.

What else do you need to know?

A course in human anatomy allows you to clearly understand what cartilage tissue is needed for: to ensure mobility while maintaining elasticity, stability, and safety. These fabrics are dense and guarantee mechanical protection. Modern anatomy as a science is characterized by an abundance of terms, including complementary and mutually replacing each other. So, if we are talking about the vitreous cartilaginous tissue of the spine, then it is assumed that we are talking about hyaline. It is this tissue that forms the ends of the bones that make up the rib cage. Some elements of the respiratory system are also created from it.

The functions of cartilage tissue from the connective tissue category are the connection of tissue and hyaline vitreous cartilage, which has a completely different structure. But the mesh cartilaginous tissue ensures the normal functioning of the epiglottis, hearing system, and larynx.

Why is cartilage tissue needed?

Nature doesn't create anything just like that. All tissues, cells, and organs have quite extensive functionality (and some tasks are still hidden from scientists to this day). As is known from anatomy today, the functions of cartilage tissue include guaranteeing the reliability of the connection of elements that provide a person with the ability to move. In particular, the bone elements of the spine are connected to each other precisely by cartilage tissue.

As it was established in the course of studies devoted to aspects of nutrition of cartilage tissue, it takes an active part in carbohydrate metabolism. This explains some of the features of regeneration. It is noted that in childhood, restoration of cartilage tissue is 100% possible, but as years pass, this ability is lost. If an adult experiences damage to cartilage tissue, he can only count on partial restoration of mobility. At the same time, the restoration of cartilage tissue is one of the problems that attracts the attention of the leading minds of medicine of our time, so it is assumed that it will be possible to find an effective pharmaceutical solution to this problem in the near future.

Joint problems: there are options

Currently, medicine can offer several methods for restoring organs and tissues damaged for various reasons. If a joint has suffered a mechanical injury or some disease has caused the destruction of biological material, in most cases the most effective solution to the problem is prosthetics. But injections for cartilage tissue will help when the situation has not yet gone so far, degenerative processes have begun, but are reversible (at least partially). As a rule, they resort to products that contain glucosamine and sodium sulfate.

When figuring out how to restore cartilage tissue in the initial stages of the disease, they usually resort to physical exercise, strictly monitoring the level of load. Therapy using anti-inflammatory drugs shows good results. As a rule, most patients are prescribed medications rich in calcium in a form that is easily absorbed by the body.

Cartilaginous connective tissue: where do the problems come from?

In most cases, the disease is provoked by previous injuries or infection of the joint. Sometimes degeneration of cartilaginous connective tissue is provoked by increased loads placed on it over a long period of time. In some cases, problems are associated with genetic background. Hypothermia of body tissues may play a role.

For inflammation, good results can be achieved by using both topical preparations and tablets. Modern medicines are formulated taking into account the hydrophilicity characteristic of the cartilage tissue of the spine and other organs. This means that topical products can quickly reach the affected area and have a therapeutic effect.

Structural features

As can be seen from the anatomy, hyaline cartilage, other cartilaginous tissues, as well as bone tissues are combined into the skeletal category. In Latin, this group of tissues received the name textus cartilaginus. Up to 80% of this tissue is water, from four to seven percent is salt, and the rest is organic components (up to 15%). The dry part of cartilage tissue is half or more (up to 70%) formed from collagen. The matrix produced by tissue cells is a complex substance that includes hyaluronic acid, glycosaminoglycans, and proteoglycans.

Tissue cells: some features

As scientists have found out, chondroblasts are young cells that usually have an irregular elongated shape. During its life, such a cell generates proteoglycans, elastin, and other components essential for the normal functioning of the joint. The cytolemma of such a cell is microvilli, presented in huge numbers. The cytoplasm contains an abundance of RNA. Such a cell is characterized by a high level of development of the endoplasmic reticulum, presented in both non-granular and granular forms. The cytoplasm of chondroblasts also contains glycogen granules, the Golgi complex, and lysosomes. Usually there are one or two nuclei in the nucleus of such a cell. The formation contains a large amount of chromatin.

A distinctive feature of chondrocytes is their large size, since these cells are already mature. They are characterized by a round, oval, and polygonal shape. Most chondrocytes are equipped with processes and organelles. Typically, such cells occupy lacunae, and around them there is an intercellular connective substance. When a lacuna contains one cell, it is classified as primary. Isogenic groups consisting of a pair or triple of cells are predominantly observed. This allows us to talk about a secondary lacuna. The wall of this formation has two layers: on the outside it is made of collagen fibers, and on the inside it is lined with proteoglycan aggregates that interact with the cartilaginous glycocalyx.

Biological characteristics of tissue

When the cartilage tissue of a joint comes into the focus of scientists' attention, it is usually studied as a cluster of chondrons - this is the name given to the functional, structural units of biological tissue. A chondrone is formed from a cell or a united group of cells, a matrix surrounding the cell, and a lacuna in the form of a capsule. Each of the three types of cartilage tissue listed above is characterized by its own unique structural features. For example, hyaline cartilage, which gets its name from the Greek word for “glass,” has a bluish tint and is characterized by cells of very different shapes and structures. Much depends on exactly what place the cell occupies inside the cartilage tissue. Typically, hyaline cartilage is formed by groups of chondrocytes. This tissue creates joints, cartilage of the ribs, and larynx.

If we consider the process of bone formation in the human body, we can see that at the primary stage most of them consist of hyaline cartilage. Over time, the transformation of joint tissue into bone occurs.

What else is special?

But fibrous cartilage is very strong, as it consists of thick fibers. Its cells are characterized by an elongated shape, a rod-shaped nucleus and cytoplasm that forms a small rim. This cartilage usually creates fibrous rings characteristic of the spine, menisci, and discs inside the joints. Cartilage covers some joints.

If we look at elastic cartilage tissue, we can see that it is quite flexible, since the matrix is rich not only in collagen, but also in elastic fibers. This tissue is characterized by round cells enclosed in lacunae.

Cartilage and cartilaginous tissue

These two terms, despite their similarity, should not be confused. Cartilaginous tissue is a type of connective biological tissue, while cartilage is an anatomical organ. Its structure contains not only cartilage tissue, but also perichondrium, which covers the tissues of the organ from the outside. In this case, the perichondrium does not cover the articular surface. This element of cartilage is formed by connective tissue consisting of fibers.

The perichondrium consists of two layers: fibrous, which covers it on the outside, and cambial, which lines the organ inside. The second one is also known as sprout. The inner layer is a cluster of poorly differentiated cells. These include chondroblasts in the inactive stage, prechondroblasts. These cells first form chondroblasts, then progress to chondrocytes. But the fibrous layer is distinguished by a developed circulatory network, represented by an abundance of vessels. The perichondrium is at the same time a protective layer, a repository of material for regenerative processes, and a tissue, thanks to which the trophism of cartilaginous tissue, in the structure of which there are no vessels, is realized. But if we consider hyaline cartilage, then the main trophic tasks in it fall on the synovial fluid, and not just on the vessels. The blood supply system to bone tissue plays a very important role.

How does this work?

The basis for the formation of cartilage and cartilaginous tissue is mesenchyme. The process of tissue growth is scientifically called chondrogistogenesis. Mesenchymal cells at points where nature provides for the presence of cartilage tissue multiply, divide, grow, and become rounded. This results in a collection of cells called a lesion. Science usually calls such places chondrogenic islands. As the process moves forward, differentiation into chondroblasts occurs, making it possible to produce fibrillar proteins that enter the environment between living cells. This leads to the formation of the first type of chondrocytes, capable of not only producing specialized proteins, but also a number of other compounds essential for the normal functioning of organs.

As cartilage tissue develops, chondrocytes differentiate, leading to the formation of the second and third types of cells in this tissue. At this same stage, gaps appear. The mesenchyme located around the cartilaginous island becomes the source of cells for the creation of perichondrium.

Features of tissue growth

The development of cartilage is usually divided into two stages. First, tissues undergo a period of interstitial growth, during which chondrocytes actively multiply and produce intercellular substance. Then comes the stage of oppositional growth. Here the “main characters” are the chondroblasts of the perichondrium. In addition, tissue overlays located on the periphery of the organ provide indispensable assistance for the formation and functioning of cartilage tissue.

As the body as a whole, and cartilage tissue in particular, ages, degenerative processes are expected. The most prone to this are hyaline cartilages. Elderly people often experience pain caused by salt detachments in the deep cartilaginous layers. Calcium compounds accumulate more often, which leads to tissue chalking. Vessels grow into the affected area, cartilage tissue is gradually transformed into bone tissue. In medicine, this process is called ossification. But elastic tissues are not damaged by such changes, they do not ossify, although they lose their elasticity over the years.

Cartilage tissue: problems of degeneration

It so happens that from the point of view of human health, cartilage tissue is one of the most vulnerable, and almost all elderly people, and often the younger generation, suffer from diseases associated with joints. There are many reasons for this: the environment, poor lifestyle, and poor nutrition. Of course, very often we get injured, encounter infections or inflammations. A one-time problem - an injury or illness - goes away, but at an older age it returns with echoes - joint pain.

Cartilage is quite sensitive to many diseases. Problems with the musculoskeletal system arise if a person is faced with a hernia, dysplasia, arthrosis, or arthritis. Some suffer from insufficient natural collagen synthesis. With age, chondrocytes degenerate, and cartilage tissue suffers greatly from this. In many cases, the best therapeutic effect is achieved by surgical intervention, when the affected joint is replaced with an implant, but this solution is not always applicable. If there is a possibility of restoration of natural cartilage tissue, this chance should not be neglected.

Joint diseases: how do they manifest?

Most people suffering from such pathologies can predict weather changes more accurately than any forecast: the joints affected by the disease respond to the slightest changes in the surrounding space with excruciating, nagging pain. If a patient suffers from damage to the joints, he should not move sharply, as the tissues react to this with sharp, severe pain. As soon as similar symptoms begin to appear, you should immediately make an appointment with a doctor. It is much easier to cure a disease or block its development if you start the fight at an early stage. Delay leads to the fact that regeneration becomes completely impossible.

Quite a lot of drugs have been developed to restore the normal functionality of cartilage tissue. Mostly they belong to the non-steroidal category and are designed to block inflammation. Painkillers are also available - tablets and injections. Finally, special chondroprotectors have recently become widespread.

How to treat?

The most effective remedies against degenerative processes in cartilage tissue affect the cellular level. They block inflammatory processes, protect chondrocytes from negative influences, and also stop the degenerative activity of various aggressive compounds that attack cartilage tissue. If inflammation has been effectively blocked, the next step in therapy is usually to restore the intercellular connection. For this purpose, chondroprotectors are used.

Several products from this group have been developed - they are built on different active components, which means they differ in the mechanism of action on the human body. All drugs in this group are effective only when taken over a long course, which allows one to achieve really good results. Preparations made with chondroitin sulfate are especially widespread. This is glucosamine, which is involved in the formation of cartilage proteins and helps restore tissue structure. Due to the supply of the substance from an external source to all types of cartilage tissue, the process of production of collagen and hyalic acid is activated, and the cartilage is independently restored. With proper use of medications, you can quickly restore joint mobility and get rid of pain.

Another good option is products containing other glucosamines. They restore tissue from various types of damage. Under the influence of the active component, metabolism in the cartilage tissues of the joint is normalized. Also recently, drugs of animal origin have been used, that is, made from biological material obtained from animals. Most often these are tissues from calves, aquatic creatures. Therapy using mucopolysaccharides and medications based on them shows good results.