How to draw cartilage. Cartilage tissue Location of cartilage in the body n

Hello my friends!

In this article, we will explore what is cartilage of the knee. Consider what cartilage consists of and what function they have. As you understand, cartilage tissue is the same in all joints of our body, and everything described below applies to other joints.

The ends of our bones in the knee joint are covered with cartilage, between them lie two menisci - these are also cartilage, but only slightly different in composition. Read about menisci in the article "". I will only say that cartilage and menisci differ in the type of cartilage tissue: bone cartilage is hyaline cartilage, and the menisci fibrocartilage. This is what we will analyze now.

The thickness of the cartilage covering the ends of the bone is on average 5-6 mm, it consists of several layers. The cartilage is dense and smooth, which allows the bones to easily slide relative to each other during flexion and extension movements. With elasticity, cartilage acts as a shock absorber during movements.

In a healthy joint, depending on its size, fluid is from 0.1 to 4 ml, the distance between cartilage (articular space) is from 1.5 to 8 mm, acid-base balance is 7.2-7.4, water is 95% , protein 3%. The composition of cartilage is similar to blood serum: 200-400 leukocytes per 1 ml, of which 75% are lymphocytes.

Cartilage is a type of connective tissue in our body. The main difference between cartilage tissue and others is the absence of nerves and blood vessels that directly feed this tissue. The blood vessels would not withstand the loads and constant pressure, and the presence of nerves there would give off pain with each of our movements.

Cartilage is designed to reduce friction at the junctions of bones. They cover both heads of the bone and the inner side of the patella (patella). Constantly bathed in synovial fluid, they ideally reduce the processes of friction in the joints to zero.

Cartilage does not have access to blood vessels and nutrition, respectively, and if there is no nutrition, then there is no growth or repair. But cartilage is also made up of living cells, and they also need nutrition. They receive food due to the same synovial fluid.

The meniscus cartilage is riddled with fibers, which is why it is called fibrocartilage and is denser and harder than hyaline in structure, therefore it has greater tensile strength and can withstand pressure.

Cartilages differ in the ratio of fibers: . All this gives the cartilage not only hardness, but also elasticity. Working like a sponge under stress, cartilage and menisci are compressed, unclenched, flattened, stretched, as you wish. They constantly absorb a new portion of the liquid and give the old one, make it constantly circulate; at the same time, the liquid is enriched with nutrients and again carries them to the cartilage. We will talk about synovial fluid later.

The main components of cartilage

articular cartilage is a complex fabric. Consider the main components of this fabric. make up almost half of the intercellular space in articular cartilage. Collagen in its structure consists of very large molecules intertwined in triple helixes. This structure of collagen fibers allows the cartilage to resist any kind of deformation. Collagen gives tissue elasticity. give elasticity, the ability to return to its original state.

The second important element of cartilage is water, which is found in large quantities in the intercellular space. Water is a unique natural element, it is not subject to any deformation, it cannot be stretched or compressed. This adds to the cartilage tissue stiffness and elasticity. Besides than more water, the better and more functional is the interarticular fluid. It spreads and circulates easily. With a lack of water, the joint fluid becomes more viscous, less fluid and, of course, does not perform its role in providing nutrition to the cartilage. !

Glycosamines- substances produced by the cartilaginous tissue of the joints are also part of the synovial fluid. Structurally, glucosamine is a polysaccharide that serves as an important constituent of cartilage.

Glucosamine is a precursor of glycosaminoglycans (the main component of articular cartilage), therefore it is believed that its additional use from the outside can contribute to the restoration of cartilage tissue.

In our body, glucosamine binds cells and is part of cell membranes and proteins, making tissues stronger and more resistant to stretching. Thus, glucosamine supports and strengthens our joints and ligaments. With a decrease in the amount of glucosamines, the resistance of cartilage tissue to stress also decreases, the cartilage becomes more susceptible to damage.

The restoration of cartilage tissue and the production of the necessary compounds and substances are dealt with chondrocytes.

Chondrocytes, by their nature, do not differ from other cells in terms of development and regeneration, their metabolic rate is sufficiently high. But the problem is that there are very few of these same chondrocytes. In articular cartilage, the number of chondrocytes is only 2-3% of the mass of cartilage. Therefore, the restoration of cartilage tissue is so limited.

So, cartilage nutrition is difficult, cartilage tissue renewal is also a very long-term process, and recovery is even more problematic. What to do?

Considering all of the above, we come to the conclusion that in order for the cartilage of the knee joint to recover, it is necessary to achieve a high number and activity of chondrocyte cells. And our task is to provide them with complete nutrition, which they can only get through the synovial fluid. But, even if the nutrition is the richest, it will not reach its goal without the movement of the joint. That's why, move more - recovery is better!

With prolonged immobilization of the joint or the entire leg (gypsum, splints, etc.), not only muscles decrease and atrophy; it has been established that cartilage tissue also decreases, since it does not receive enough nutrition without movement. I will repeat myself for the hundredth time, but this is another proof of the need for constant movement. Man is created by nature in such a way that he must constantly run for food and run away from the mammoth, like other animals. Excuse me if I offend some of the "Crowns of the Creation of Nature" by this. On the scale of evolutionary development, we have gone too little way for the body to behave differently, it has not yet adapted to other conditions of existence. And if the body feels that something in its composition is not needed or does not work well, it gets rid of it. Why feed something that does not benefit? They stopped walking with their feet - the legs atrophy, the bodybuilder stopped swinging (using all his muscle mass) - he was immediately blown away. Well, I digress.

In other articles, of course, we will touch on issues (operational methods and conservative ones), their nutrition and movement. What I, with my cartilage injury, am trying to implement. I'll tell you too.

In the meantime, my instructions are: , COMPLETE VARIOUS FOOD,.

You can start this minute.

All the best, don't worry!

Cartilage tissue is functionally inherent in the supporting role. It does not work in tension, like a dense connective tissue, but due to internal tension, it resists compression well and serves as a shock absorber for the bone apparatus.

This special fabric is used to fixed connection bones, forming synchondrosis. Covering the articular surfaces of the bones, softens the movement and friction in the joints.

Cartilage tissue is very dense and at the same time quite elastic. Her biochemical composition rich in dense amorphous matter. Cartilage develops from intermediate mesenchyme.

At the site of the future cartilage, mesenchymal cells multiply rapidly, their processes are shortened and the cells are in close contact with each other.

Then an intermediate substance appears, due to which mononuclear sections are clearly visible in the rudiment, which are the primary cartilaginous cells - chondroblasts. They multiply and give more and more masses of the intermediate substance.

The rate of reproduction of cartilage cells by this period is greatly slowed down, and due to the large amount of intermediate substance, they are far removed from each other. Soon, cells lose the ability to divide by mitosis, but still retain the ability to divide amitotically.

However, now the daughter cells do not diverge far, as the intermediate substance surrounding them has condensed.

That's why cartilage cells are located in the mass of the main substance in groups of 2-5 or more cells. All of them come from one initial cell.

Such a group of cells is called isogenic (isos - equal, identical, genesis - occurrence).

Rice. one.

A - hyaline cartilage of the trachea;

B - elastic cartilage of the auricle of the calf;

B - fibrocartilage of the intervertebral disc of the calf;

a - perichondrium; b ~ cartilage; in - an older section of cartilage;

• 1 - chondroblast; 2 - chondrocyte;
• 3 - isogenic group of chondrocytes; 4 - elastic fibers;
• 5 - bundles of collagen fibers; 6 - the main substance;
• 7 - chondrocyte capsule; 8 - basophilic and 9 - oxyphilic zone of the main substance around the isogenic group.

Cells of the isogenic group do not divide by mitosis, they give little intermediate substance of a slightly different chemical composition, which forms cartilaginous capsules around individual cells, and fields around the isogenic group.

The cartilage capsule, as revealed by electron microscopy, is formed by thin fibrils concentrically located around the cell.

Consequently, at the beginning of the development of the cartilage tissue of animals, its growth occurs by increasing the mass of the cartilage from the inside.

Then the oldest part of the cartilage, where cells do not multiply and no intermediate substance is formed, ceases to increase in size, and cartilage cells even degenerate.

However, the growth of cartilage as a whole does not stop. Around the obsolete cartilage, a layer of cells separates from the surrounding mesenchyme, which become chondroblasts. They secrete around themselves the intermediate substance of the cartilage and gradually thicken with it.

At the same time, as they develop, chondroblasts lose the ability to divide by mitosis, form less intermediate substance and become chondrocytes. On the layer of cartilage formed in this way, due to the surrounding mesenchyme, more and more layers of it are superimposed. Consequently, cartilage grows not only from the inside, but also from the outside.

In mammals, there are: hyaline (vitreous), elastic and fibrous cartilage.

Hyaline cartilage (Fig. 1--A) is the most common, milky white and somewhat translucent, so it is often called vitreous.

It covers the articular surfaces of all bones; costal cartilages, cartilages of the trachea and some cartilages of the larynx are formed from it. Hyaline cartilage consists, like all tissues of the internal environment, of cells and an intermediate substance.

Cartilage cells are represented by chondroblasts and chondrocytes. It differs from hyaline cartilage in the strong development of collagen fibers, which form bundles that lie almost parallel to each other, as in tendons!

There is less amorphous substance in fibrous cartilage than in hyaline. Rounded light cells of fibrocartilage lie between the fibers in parallel rows.

In places where fibrocartilage is located between hyaline cartilage and formed dense connective tissue, a gradual transition from one type of tissue to another is observed in its structure. Thus, closer to the connective tissue, collagen fibers in cartilage form coarse parallel bundles, and cartilage cells lie in rows between them, like fibrocytes of dense connective tissue. Closer to the hyaline cartilage, the bundles are divided into individual collagen fibers that form a delicate network, and the cells lose their correct location.

The basis of the musculoskeletal system are cartilage tissues. It is also part of the structures of the face, becoming the place of attachment of muscles and ligaments. The histology of the cartilage is not presented. large quantity cellular structures, fibrous formations and nutrients. This ensures sufficient damping function.

What does it represent?

Cartilage is a type of connective tissue. 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 the main substance, where the fibers are located, providing the elasticity of the cartilage. Cells in the thickness of these structures form groups or are placed separately. The location is usually near the bones.

Cartilage varieties

Depending on the features of the structure and localization in the human body, there is such a classification of cartilage tissues:

• Hyaline cartilage contains chondrocytes, placed in the form of rosettes. The intercellular substance is larger in volume than the fibrous substance, and the filaments 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 a lower density and transparency, having sufficient elasticity. This matter makes up the cartilages of the face, as well as the structures of the middle formations in the bronchi.
• Fibrous cartilage is a connective tissue that performs the functions of strong shock-absorbing elements and contains a significant amount of fibers. Localization of the fibrous substance is located throughout the musculoskeletal system.

Properties and structural features of cartilage tissue

On the histological preparation, it is seen that the tissue cells are located loosely, being in an abundance of intercellular substance.

All types of cartilage are able to take on and resist the compressive forces that occur during movement and load. This ensures an even distribution of gravity and a reduction in the load on the bone, which stops its destruction. The skeletal zones, 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 a large amount of intercellular substance, and the cells are located loosely in it, form clusters or are located separately. The main substance of the cartilaginous structure is involved in the processes of carbohydrate metabolism in the body.

This type of material in the human body, like the rest, is composed of cells and intercellular substance of cartilage. A feature in a small number of cellular structures, due to which the properties of the tissue are provided. Mature cartilage refers to a loose structure. Elastic and collagen fibers perform a supporting function in it. The general plan of the structure includes only 20% of the cells, and everything else is fibers and amorphous matter. This is due to the fact that due to the dynamic load, the vascular bed of the tissue is poorly expressed and therefore it is forced to feed on the main substance of the cartilage tissue. In addition, the amount of moisture that is in it performs shock-absorbing functions, smoothly relieving tension in bone tissues.

What are they made of?

The trachea and bronchi are composed of hyaline cartilage.

Each type of cartilage has unique properties due to the difference in location. The structure of hyaline cartilage differs from the rest in a smaller number of fibers and a large filling with amorphous matter. In this regard, it is not able to withstand heavy loads, since its tissues are destroyed by bone friction, 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 mainly by fibrous matter. Its variety includes a 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 randomly. Sometimes their clusters resemble islets with large areas of absence of cellular elements. At the same time, a mature cell type and a young one, which is called chondroblasts, are located together. They are formed by the perichondrium and have interstitial growth, and in the process of their development they produce various substances.

Chondrocytes are a 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 an amorphous substance:

Hyaluronic acid is contained in an amorphous substance.

• proteins;
• glycosaminoglycans;
• proteoglycans;
• hyaluronic acid.

In the embryonic period, most bones are hyaline tissues.

The structure of the intercellular substance

It consists of two parts - these are fibers and an amorphous substance. At the same time, fibrillar structures are randomly located in the tissue. The histology of cartilage is affected by the production by its cells of chemicals responsible for the density, transparency and elasticity. The structural features of hyaline cartilage are the presence of only collagen fibers in its composition. If not enough is allocated hyaluronic acid, then it destroys tissues due to degenerative-dystrophic processes in them.

In the human body, cartilage tissues serve as a support and connection between the structures of the skeleton. There are several types of cartilage structures, each of which has its own location and performs its tasks. Skeletal tissue undergoes pathological changes due to intense physical activity, congenital pathologies, age and other factors. To protect yourself from injuries and diseases, you need to take vitamins, calcium supplements and not be injured.

The value of cartilage structures

Articular cartilage holds skeletal bones, ligaments, muscles and tendons together into a single musculoskeletal system. It is this type of connective tissue that provides cushioning during movement, protecting the spine from damage, preventing fractures and bruises. The function of cartilage is to make the skeleton elastic, elastic and flexible. In addition, cartilage forms a supporting frame for many organs, protecting them from mechanical damage.

Features of the structure of cartilage tissue

The specific gravity of the matrix exceeds the total mass of all cells. The general plan of cartilage structure consists of 2 key elements: intercellular substance and cells. During the histological examination of the sample under the lenses of a microscope, the cells are located on a relatively smaller percentage of the area of ​​space. The intercellular substance contains about 80% water in the composition. The structure of hyaline cartilage provides its main role in the growth and movement of the joints.

intercellular substance

The strength of cartilage is determined by its structure.

The matrix, as an organ of cartilaginous tissue, is heterogeneous and contains up to 60% amorphous mass and 40% chondrin fibers. Fibrils histologically resemble human skin collagen, but differ in more chaotic placement. The ground substance of cartilage consists of protein complexes, glycosaminoglycans, hyaluronan compounds and mucopolysaccharides. These components provide durable cartilage properties, keeping it permeable to essential nutrients. There is a capsule, its name is perichondrium, it is a source of cartilage regeneration elements.

Cellular composition

Chondrocytes are located in the intercellular substance rather chaotically. The classification divides cells into undifferentiated chondroblasts and mature chondrocytes. The precursors are formed by the perichondrium, and as they move into deeper tissue balls, the cells differentiate. Chondroblasts produce matrix ingredients that include proteins, proteoglycans, and glycosaminoglycans. Young cells by division provide interstitial growth of cartilage.

Chondrocytes located in deep tissue spheres are grouped by 3-9 cells, known as "isogenic groups". This mature cell type has a small nucleus. They do not divide, and their metabolic rate is greatly reduced. The isogenic group is covered by intertwined collagen fibers. The cells in this capsule are separated by protein molecules and have a variety of shapes.

With degenerative-dystrophic processes, multinucleated chondroclast cells appear, which destroy and absorb tissues.

The table presents the main differences in the structure of cartilage tissue types:

View	Peculiarities
Hyaline	Thin collagen fibers
	Has basophilic and oxyphilic zones
elastic	Made up of elastin
	Very flexible
	Has a cellular structure
Fibrous	Formed from a large number of collagen fibrils
	Chondrocytes are comparatively larger
	Lasting
	Able to withstand high pressure and compression

Blood supply and nerves

The tissue is not supplied with blood from its own vessels, but receives it by diffusion from adjacent ones.

Due to the very dense structure, cartilage does not have blood vessels of even the smallest diameter. Oxygen and all the nutrients necessary for life and functioning come by diffusion from nearby arteries, perichondrium or bone, and are also extracted from the synovial fluid. Decay products are also excreted diffusely.

In the upper balls of the perichondrium there are only a small number of individual branches of nerve fibers. Thus, the nerve impulse is not formed and does not spread in pathologies. The localization of the pain syndrome is determined only when the disease destroys the bone, and the cartilage tissue structures in the joints are almost completely destroyed.

Varieties and functions

Depending on the type and relative position of fibrils, histology distinguishes the following types of cartilage tissue:

• hyaline;
• elastic;
• fibrous.

Each type is characterized by a certain level of elasticity, stability and density. The location of the cartilage determines its tasks. The main function of cartilage is to ensure the strength and stability of the joints of the parts of the skeleton. The smooth hyaline cartilage found in the joints makes it possible for the bones to move. Due to its appearance, it is called vitreous. The physiological conformity of the surfaces guarantees a smooth glide. The structural features of hyaline cartilage and its thickness make it an integral part of the ribs, rings of the upper respiratory tract.

The shape of the nose is formed by an elastic type of cartilage.

Elastic cartilage forms appearance, voice, hearing and breathing. This applies to the structures that are in the skeleton of the small and medium-sized bronchi, auricles and the tip of the nose. The elements of the larynx are involved in the formation of a personal and unique voice timbre. Fibrous cartilage connects skeletal muscles, tendons, and ligaments to vitreous cartilage. Intervertebral and intra-articular discs and menisci are built from fibrous structures; they cover the temporomandibular and sternoclavicular joints.

Cartilage tissue is a skeletal connective tissue that performs supporting, protective and mechanical functions.

The structure of cartilage

Cartilaginous tissue consists of cells - chondrocytes, chondroblasts and dense intercellular substance, consisting of amorphous and fibrous components.

Chondroblasts

Chondroblasts located singly along the periphery of the cartilaginous tissue. They are elongated flattened cells with basophilic cytoplasm containing a well-developed granular endoplasmic reticulum and the Golgi apparatus. These cells synthesize the components of the intercellular substance, release them into the intercellular environment and gradually differentiate into the definitive cells of the cartilage tissue - chondrocytes.

Chondrocytes

Chondrocytes by degree of maturity, according to morphology and function are divided into cells I, II and III type. All varieties of chondrocytes are localized in the deeper layers of cartilage tissue in special cavities - gaps.

Young chondrocytes (type I) divide mitotically, but the daughter cells end up in the same gap and form a group of cells - an isogenic group. The isogenic group is a common structural and functional unit of cartilage tissue. The location of chondrocytes in isogenic groups in different cartilage tissues is not the same.

intercellular substance cartilage tissue consists of a fibrous component (collagen or elastic fibers) and an amorphous substance, which contains mainly sulfated glycosaminoglycans (primarily chondroitin sulfuric acids), as well as proteoglycans. Glycosaminoglycans bind a large amount of water and determine the density of the intercellular substance. In addition, the amorphous substance contains a significant amount of minerals that do not form crystals. Vessels in the cartilage tissue are normally absent.

Cartilage classification

Depending on the structure of the intercellular substance, cartilage tissues are divided into hyaline, elastic and fibrous cartilage tissue.

hyaline cartilage tissue

characterized by the presence of only collagen fibers in the intercellular substance. At the same time, the refractive index of the fibers and the amorphous substance is the same, and therefore the fibers in the intercellular substance are not visible on histological preparations. This also explains a certain transparency of cartilage, consisting of hyaline cartilage tissue. Chondrocytes in isogenic groups of hyaline cartilage tissue are arranged in the form of rosettes. By physical properties hyaline cartilage tissue is characterized by transparency, density and low elasticity. In the human body, hyaline cartilage tissue is widespread and is part of the large cartilage of the larynx. (thyroid and cricoid), trachea and large bronchi, makes up the cartilaginous parts of the ribs, covers the articular surfaces of the bones. In addition, almost all the bones of the body in the process of their development pass through the stage of hyaline cartilage.

Elastic cartilage tissue

characterized by the presence of both collagen and elastic fibers in the intercellular substance. In this case, the refractive index of elastic fibers differs from the refraction of an amorphous substance, and therefore elastic fibers are clearly visible in histological preparations. Chondrocytes in isogenic groups in elastic tissue are arranged in the form of columns or columns. In terms of physical properties, elastic cartilage is opaque, elastic, less dense, and less transparent than hyaline cartilage. She is part of elastic cartilage: auricle and cartilaginous part of the external auditory canal, cartilages of the external nose, small cartilages of the larynx and middle bronchi, and also forms the basis of the epiglottis.

Fibrous cartilage tissue

characterized by the content in the intercellular substance of powerful bundles of parallel collagen fibers. In this case, chondrocytes are located between the bundles of fibers in the form of chains. According to physical properties, it is characterized by high strength. It is found only in limited places in the body: it is part of the intervertebral discs (annulus fibrosus) and also localized in the places of attachment of ligaments and tendons to hyaline cartilage. In these cases, a gradual transition of connective tissue fibrocytes into cartilage chondrocytes is clearly seen.

There are the following two concepts that should not be confused - cartilage tissue and cartilage. cartilage tissue- This is a type of connective tissue, the structure of which is described above. Cartilage is an anatomical organ made up of cartilage and perichondrium.

perichondrium

The perichondrium covers the cartilaginous tissue from the outside (with the exception of the cartilaginous tissue of the articular surfaces) and consists of fibrous connective tissue.

There are two layers in the perichondrium:

external - fibrous;

internal - cellular or cambial (growth).

In the inner layer, poorly differentiated cells are localized - prechondroblasts and inactive chondroblasts, which, in the process of embryonic and regenerative histogenesis, first turn into chondroblasts, and then into chondrocytes. The fibrous layer contains a network of blood vessels. Consequently, the perichondrium, as an integral part of the cartilage, performs the following functions: provides trophic avascular cartilage tissue; protects cartilage; provides regeneration of cartilaginous tissue when it is damaged.