The structure of the human long tubular bone diagram. Tubular bones: structure and functions

The structure of the tubular bone is a complex structure in the shape of a trihedron or cylinder.

It combines multifunctional elements and substances. The feature that distinguishes this type of bone in the body or animal from another is the predominance of their length over width.

Components

What is each tubular bone made of?

• Diaphysis This is the body of the bone, due to the growth of which it lengthens and increases. It consists of the so-called compact substance - plates located even deeper in the bone. They form osteons - cylindrical bodies within which vessels pass.
• Epiphysis The final elements of a bone, located at its two ends and involved in the formation of joints.
• Hyaline cartilage. This is the covering of the epiphyses of the bone.
• Metaphysics The middle part of each long bone. During childhood, as well as his adolescence It is in this part that the plates from which the epiphysis is formed are located.
• Periosteum. It covers the bone, thereby forming the outer layer. It is through the periosteum that capillaries (small vessels), as well as nerves, pass through special channels. They must provide nutrition and communication with the deep layers. The periosteum is a plate that consists of connective tissue formed by fibrous fibers. They are located outside, and inside there are osteoblasts - looser tissue.
• Spongy substance. Located in the next layer after the compact one. The spongy substance got its name because of its porous structure, reminiscent of a sponge. Contains trabeculae - bone crossbars. They also consist of plates.
• Bone marrow. This is a very important part. It is in the bone marrow, located in the middle of the bones, that hematopoiesis occurs. It consists of a yellow and a red part, with the yellow consisting of fat cells and the red part of reticular tissue.
• Osteoblasts and osteoclasts. Destroying and creating tissue found in the red bone marrow.

The periosteum or periosteum makes up the upper part of each long bone. Its inner layer is also called cellular, and its outer layer is fibrous, formed mostly by connective tissue. Its deep part exists thanks to cambial cells, preosteoblasts and osteoblasts.

But the description of the structure of the periosteum does not end there. Cambial cells are spindle-shaped bodies containing all the structural elements of the cell. The only difference is the amount of cytoplasm. This intracellular substance is found in small quantities in cambial cells.

Preosteoblasts are oval cells that are needed for the synthesis of mucopolysaccharides. Osteoblasts also synthesize their substance. They produce the protein collagen.

The diaphysis, the main constituent element, consists of bone plates. Their thickness ranges from four to fifteen micrometers. The arrangement of these thin microplates in a certain order is usually called Haversian systems or osteons.

In addition, the diaphysis is divided into three parts:

• The first, outer layer of general purpose plates, also called general.
• Osteons or osteon part, middle.
• Inner layer of general purpose plates.

The peculiarity of general plates is that they cover the bone in a non-circular manner. This leaves room for the next plate to be overlapped from the middle. These components are better developed closer to the center of the bone, where they are in direct contact with the medullary bone cavity.

Channels that are often located in the outer plates are called Volkmann channels. It is along them that the nerves and... pass from the periosteum into the bone. In addition to them, collagen fibers penetrate inside at different angles of inclination.

Because of their high penetrating ability, they are called perforating and also Shar Pei. They can even branch, but only in the outermost layer of the general plates. In osteons - next layer- they don't penetrate.

They are similar to cylinders in shape. Osteons are a kind of collection of plates, and according to a certain pattern. They are separated from each other by cleavage lines. These are strong cementing plate assemblies.

Osteons are located along a certain axis, forming their own layer. And the innermost shell - the third - is called endosteum. Its thickness is 2 microns. After it there are no more layers - the bone marrow begins.

Bone has several layers of different special tissue or layers. They are different from each other, but perform important functions.

What processes can occur in bones?

The structure of the human tubular bone is integrally related to the consideration of its aging process. Over time, as the bone (tubular) “matures,” the following processes become probable. The population (number) of osteoblasts decreases. The compact layer becomes thinner, and the spongy substance is modified and rebuilt.

The growth of tubular bones is one of the main processes that can occur in them. It begins even before birth and ends, according to scientists and doctors, at the age of twenty or a little later.

Changes in its size occur both in width and in length. As in many other processes occurring in the body. A double multidirectional action occurs in the bones.

On the one hand, obsolete bone tissue (epiphyseal plate) is constantly destroyed there. On the other hand, a new one is being developed. But with the passage of time and the aging of systems in the body, it becomes thinner. The metapiphyseal cartilaginous plate, which is responsible for new bone formations, consists of:

• Border zone.
• Columnar zone (this is an area of ​​cells that are constantly and actively dividing).
• The vesicular zone (altered dystrophic cells are located here).

Composition of the border zone: round and oval cells, isogenic groups. The latter are responsible for the connection of the cartilage plate with the epiphysis bone. There are also capillaries in the cavities, they are needed for nutrition. The second zone is where cells actively multiply. It is called columnar because columns are formed along the axis of the bone.

The ends of such long bones consist of glycogen and phosphatase (alkaline). This is the area where hormones can influence the processes that occur inside. The third zone - vesicular cells - is the area of ​​​​destruction of chondrocytes.

The centers of action in the diaphysis and epiphysis merge together after a certain period of time, laid down in advance in the bone marrow. All of the above related to the growth of bones in length. They increase in width due to the action of the periosteum. It is active while a person grows into an adult.

Essence of Bone

The structure of the tubular bone as an organ is useful and educational information that describes below the internal essence of the tubular bone. This is a separate part of the entire skeleton. It is the hardest organ, occupying a precise and permanent position in the body.

The functions of different tubular bones, oddly enough, are different. But in terms of strength, biologists are ready to compare these organs with metal products, they are so strong. Although the chemical component in the bone is half water. Also inside there is about twenty percent phosphate, some ossein and fifteen percent fat.

If you dry the bone for an experiment, then it turns out that two thirds are inorganic substances(for hardness). And one third is organic (for elasticity). Accumulated minerals (also inorganic, as mentioned above) contribute to the aging and deterioration of bone and all its constituent tissues.

The osteon, the growth mechanism of which has already been described, consists of five or more plates. Usually their number does not exceed twenty pieces. The whole point is whether the plates fit tightly to each other. If it is not dense, there will be a more spongy substance, but if it is dense, it will be a solid substance.

By the way, there are long and short tubular ones. The long ones (first category) include those located in the sternum, the short ones (second category) include the vertebrae and sacrum. The metaphysis is the middle part of the bone (transitional).

Each type of brain has its time. That is why the baby's bones contain only red. The brain is so at a young age produces, but fat (yellow brain) does not yet have time to accumulate. Moreover, small people need increasing portions of blood, as the body grows along with its needs.

This is interesting to know: one of the functions of the outer fibrous layer is trophic. The healing of fractures and the growth of all tubular bones at the right time occurs thanks to this.

According to some data, aging of bones and tissue occurs on average later in men than in women. Namely, by the age of twenty-five. And this is compared to twenty-three to twenty for women.

So, an overview, albeit brief, of the complexity and growth of bones has been carried out. The aging process, which can also take place, has not been spared. The main thing is to understand all the cause-and-effect relationships of the emergence and development of vital forces and internal resources of the body.

Trabeculae - another special word - are plates located in a certain order to their neighbors. This is the same building material. By understanding the processes occurring inside the body and bones in particular, you can influence future health and longevity through prevention and knowledge.

Elena Malysheva will talk about how to strengthen bones in the video:

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Bone(os) is an organ that is a component of the system of organs of support and movement, having a typical shape and structure, characteristic architecture of blood vessels and nerves, built primarily from bone tissue, covered externally with periosteum (periosteum) and containing bone marrow (medulla osseum) inside.

Each bone has a specific shape, size and position in the human body. The formation of bones is significantly influenced by the conditions in which bones develop and the functional loads that bones experience during the life of the body. Each bone is characterized by a certain number of sources of blood supply (arteries), the presence of certain places of their localization and the characteristic intraorgan architecture of blood vessels. These features also apply to the nerves innervating this bone.

Each bone consists of several tissues that are in certain proportions, but, of course, the main one is lamellar bone tissue. Let us consider its structure using the example of the diaphysis of a long tubular bone.

The main part of the diaphysis of the tubular bone, located between the outer and inner surrounding plates, consists of osteons and intercalated plates (residual osteons). The osteon, or Haversian system, is a structural and functional unit of bone. Osteons can be viewed in thin sections or histological preparations.

Internal structure bones: 1 - bone tissue; 2 - osteon (reconstruction); 3 - longitudinal section of osteon

External structure humerus: 1 - proximal (upper) epiphysis; 2 - diaphysis (body); 3 - distal (lower) epiphysis; 4 - periosteum

Human skeleton (front view): 1 - skull; 2 - sternum; 3 - collarbone; 4 - ribs; 5 - humerus; 6 - ulna; 7 - radius; 8 - hand bones; 9 - pelvic bone; 10 - femur; 11 - patella; 12 - fibula; 13 - tibia; 14 - foot bones	Human skeleton (back view): 1 - parietal bone; 2 - occipital bone; 3 - shoulder blade; 4 - humerus; 5 - ribs; 6 - vertebrae; 7 - bones of the forearm; 8 - carpal bones; 9 - metacarpus bones; 10 - phalanges of fingers; 11 - femur; 12 - tibia; 13 - fibula; 14 - tarsal bones; 15 - metatarsal bones; 16 - phalanges of fingers

Bones together with their compounds in the human body make up the skeleton. The skeleton is understood as a complex of dense anatomical formations that perform primarily mechanical functions in the life of the body. We can distinguish a hard skeleton, represented by bones, and a soft skeleton, represented by ligaments, membranes and cartilaginous joints.

Individual bones and the human skeleton as a whole perform various functions in the body. Bones of the trunk and lower limbs perform a supporting function for soft tissues (muscles, ligaments, fascia, internal organs). Most bones are levers. Muscles that provide locomotor function (moving the body in space) are attached to them. Both of these functions allow us to call the skeleton a passive part of the musculoskeletal system.

The human skeleton is an anti-gravity structure that counteracts the force of gravity. Under the influence of the latter, the human body is pressed to the ground, while the skeleton prevents the body from changing its shape.

The bones of the skull, torso and pelvic bones serve as protection against possible damage to vital organs, large vessels and nerve trunks. Thus, the skull is a container for the brain, the organ of vision, the organ of hearing and balance. The spinal cord is located in the spinal canal. Rib cage protects the heart, lungs, large vessels and nerve trunks. The pelvic bones protect the rectum from damage, bladder and internal genital organs.

Most bones contain red bone marrow, which is a hematopoietic organ and also an organ of the body's immune system. At the same time, the bones protect the red bone marrow from damage and create favorable conditions for its trophism and the maturation of blood cells.

Bones take part in mineral metabolism. They contain numerous chemical elements, mainly calcium and phosphorus salts. Thus, when radioactive calcium is introduced into the body, within a day more than half of this substance accumulates in the bones.

Joint diseases

Bone- the hardest substance present in the human body after tooth enamel. Its unusually high resistance is due to its structural features: bone substance is a special type of connective tissue - bone tissue, characteristic features which are solid, fibrous, impregnated with mineral salts intercellular substance and stellate cells equipped with numerous processes.

Classification of bones

Each bone is an independent organ and consists of two parts: the outer one - the periosteum and the inner one, formed by bone tissue. Inside, in the bone marrow cavities, there is bone marrow - the most important hematopoietic organ in humans.

Depending on the form determined by the function performed, there are the following groups bones

• long (tubular);
• short (spongy);
• flat (wide);
• mixed (abnormal);
• pneumatic.

Long (tubular) bone has an elongated, cylindrical or triangular middle part - the body of the bone, the diaphysis. Its thickened ends are called epiphyses. Each epiphysis has an articular surface covered with articular cartilage, which serves to connect to adjacent bones. Tubular bones make up the skeleton of the limbs and act as levers. There are long bones (humerus, femur, bones of the forearm and tibia) and short bones (metacarpals, metatarsals, phalanges of the fingers).

Short (cancellous) bone has the shape of an irregular cube or polyhedron. Such bones are located in certain areas of the skeleton, where their strength is combined with mobility: in the joints between bones (carpus, tarsus).

Flat (wide) bones participate in the formation of body cavities and also perform a protective function (bones of the cranial vault, pelvic bones, sternum, ribs). At the same time, they provide extensive surfaces for muscle attachment, and also, along with tubular bones, are receptacles for bone marrow.

An important feature of evolution is the presence of short bones in the human wrist (which makes the hand suitable for performing various manipulations) and in the toes (which gives special stability in a standing position)

Mixed (abnormal) bones They have a complex structure and varied shape. For example, the vertebral body is a spongy bone, and its arch and processes are flat.

Air bones They have a cavity in the body lined with mucous membrane and filled with air. These include some bones of the skull: frontal, sphenoid, ethmoid, maxilla.

As bone grows, layers of bone tissue are formed successively.

Spongy bone tissue forms the inner part of the bone. Its porous structure makes the bones light and resistant to crushing. Small cavities in the spongy tissue are filled with red bone marrow, which produces blood cells.

Compact bone tissue, tough and very dense, forms the outer layer of bone and provides resistance to pressure and external influences. On its surface there are Haversian canals (osteons), through which blood vessels pass that feed the bones, and inside, in the medullary canal, there is yellow bone marrow - tissue with fatty inclusions.

Chemical composition of bones

Bone tissue is rich in minerals (especially calcium), which provide it with high strength, and collagen, a protein that gives it flexibility. It is constantly renewed due to the balance between two types of special cells: osteoblasts, which produce bone tissue, and osteoclasts, which destroy it. Osteoblasts play a key role in the growth and maintenance of the skeleton and the “repair” of bones after fractures.

The composition of bones includes both organic (fats, proteins, carbohydrate compounds) and inorganic substances (mainly mineral compounds of phosphorus and calcium). The number of the former increases, the younger the organism; This is why bones are flexible and soft in youth, and hard and brittle in old age. In an adult, the amount of mineral substances (mainly hydroxyapatite) is about 60-70% of the bone weight, and organic substances (mainly collagen - connective tissue fibers) - from 30 to 40%. Bones have high strength and offer enormous resistance to compression; they are able to withstand destruction for an extremely long time and are among the most common remains of fossil animals. When bones are heated, they lose organic matter, but retains its shape and structure; by exposing it to acid (for example, hydrochloric), you can dissolve minerals and obtain a flexible cartilaginous skeleton of the bone.

Yellow bone marrow normally does not perform a hematopoietic function, but with large blood losses, foci of hematopoiesis appear in it. With age, the volume and mass of bone marrow change. If in newborns it accounts for approximately 1.4% of body weight, then in an adult it accounts for 4.6%.

It consists of the epiphyses and diaphysis. From the outside, the diaphysis is covered with periosteum, or periostomy(Figure 6-3). The periosteum has two layers: outer(fibrous) – formed mainly by fibrous connective tissue and internal(cellular) – contains cells osteoblasts. The vessels and nerves that feed the bone pass through the periosteum, and collagen fibers, which are called perforating fibers. Most often, these fibers branch only in the outer layer of the common plates. The periosteum connects the bone with surrounding tissues and takes part in its trophism, development, growth and regeneration.

The compact substance that forms the bone diaphysis consists of bone plates arranged in a certain order, forming three layers:

outer layer of common lamellae. In him the plates do not form complete rings around the diaphysis of the bone. This layer contains perforating channels, through which vessels enter from the periosteum into the bone.

average,osteon layer - formed by concentrically layered bone plates around the vessels . Such structures are called osteons, and the plates forming them are osteon plates. Osteons are a structural unit of the compact substance of tubular bone. Each osteon is delimited from neighboring osteons by the so-called cleavage line. The central canal of the osteon contains blood vessels with accompanying connective tissue. . All osteons are generally located parallel to the long axis of the bone. The osteon canals anastomose with each other. The vessels located in the osteon canals communicate with each other, with the vessels of the bone marrow and periosteum. In addition to osteon plates, this layer also contains insert plates(remains of old destroyed osteons) , which lie between the osteons.

inner layer of common laminae well developed only where the compact bone substance directly borders the medullary cavity.

The inside of the compact substance of the diaphysis is covered with endosteum, which has the same structure as the periosteum.

Rice. 6-3. The structure of the tubular bone. A. Periosteum. B. Compact bone substance. V. Endost. D. Bone marrow cavity. 1. Outer layer of common plates. 2. Osteonic layer. 3. Osteon. 4. Osteon channel. 5. Insert plates. 6. Inner layer of common plates. 7. Bone trabecula of spongy tissue. 8. Fibrous layer of the periosteum. 9. Blood vessels of the periosteum. 10. Perforating channel. 11. Osteocytes. (Scheme according to V. G. Eliseev, Yu. I. Afanasyev).

Growth of tubular bones– the process is very slow. It begins in humans from the early embryonic stages and ends on average by the age of 20. During the entire period of growth, the bone increases in both length and width. The growth of tubular bone in length is ensured by the presence metaepiphyseal cartilaginous growth plate, in which two opposing histogenetic processes appear. One is the destruction of the epiphyseal plate and the other, the opposite, is the constant replenishment of cartilage tissue through new formation. However, over time, the processes of destruction of the cartilaginous plate begin to prevail over the processes of neoplasm in it, as a result of which the cartilaginous plate becomes thinner and disappears.

Regeneration. Physiological regeneration of bone tissue is carried out by osteoblasts of the periosteum. However, this process is very slow.