Microscopic structure of bone. Features of the structure of bones

Laboratory work "Microscopic structure of the bone" is familiar to every schoolboy. Everyone remembers that it is thanks to the peculiarities of the cellular structure that the body has a harmonious system of organs that ensure the movement of the body in space.

Significance of the musculoskeletal system

The system of organs of motion consists of bones, muscles and connecting ligaments. This is a well-coordinated mechanism, thanks to which the body has a form, its internal organs are considerably protected from mechanical damage, individual parts and the whole organism can move in space. How important is this function? Movement is life. It is one of the signs of living organisms along with breathing, growth and reproduction of their own kind. Many organisms lead an attached lifestyle. For example, plants. But they are also characterized by growth in the direction toward the sun.

For the human body this important function is ensured by the structure of the bones of the skeleton.

Osteocytes

The microscopic structure of the bone is represented by its cells. They are called osteocytes. They have a spindle-shaped or stellate shape, a large rounded nucleus. In translation, the name of these cells means "bone".

In the cytoplasm of osteocytes, there are few permanent cellular structures called organelles. If we consider them under a microscope, we can distinguish between individual mitochondria and elements of the endoplasmic reticulum.

Bone tissue cells have an important distinctive feature. It consists in the fact that in an adult formed organism, osteocytes lose the ability to divide and the process of their wear and aging begins.

Bone

The structure and composition of human bones are determined by the structure of bone tissue. It consists of individual plates formed by osteocytes, and intercellular substance. Bone tissue is a type of connective tissue. Its characteristic feature is a large amount of intercellular substance, into which individual cells are immersed.

The same is arranged and bone tissue. Its intercellular substance is formed by minerals and collagen fibers, which are structures of protein nature.

Laboratory work "Microscopic bone structure"

Consider this variety of tissue under a large increase. Visually, the microscopic structure of the bone resembles a network. Such a structure is formed due to the numerous thin outgrowths of osteocytes, by which they are joined together. Such a network gives strength to bones. Due to the presence of collagen fibers, which contain contractile proteins, the bones are capable of compression and stretching.

The microscopic structure of the bone pattern below illustrates very well.

Chemical composition of bones

25% of the total composition of substances is water. The same percentage is accounted for by organic matter. Basically, this is an elastic collagen protein that has a fibrous structure. It gives bones such a property as elasticity. For example, the structure of a tubular bone allows it to withstand a load of 1.5 tons. Mineral substances are mainly composed of phosphorus and calcium salts. Their function is to ensure the hardness and strength of bones. Especially important is the consumption of these trace elements during the formation of the skeleton of the child. Calcium is rich in dairy products, legumes, cabbage, tomatoes, sorrel and strawberries. Phosphorus is found in products of animal origin: meat, eggs and fish.

Interesting experiments

The microscopic structure of the bone has its own characteristics. But what substances are more important for the development of this tissue? To understand this, you can conduct an experiment.

The bone is placed in an aqueous solution of hydrochloric acid. As a result, all mineral substances are dissolved. The bone becomes so flexible that it can easily be tied up in a nodule. But then our body would not have a foundation and support.

If the bone is calcined on a very slow fire, all organic substances gradually oxidize. As a result, such a fabric can simply crumble.

The conclusion is one: each group of substances gives bones certain properties, making this tissue unique and indispensable for the human body.

Classification of bones

Depending on the form, several groups of bones are distinguished. Long, which is also called tubular, form a cavity inside. It is filled with a special substance - the yellow bone marrow. It is rich in fatty tissue, nourishes bones, and also plays an important role in metabolic processes. These bones, thanks to the features of the structure, combine strength and lightness. Their examples are the femoral - the longest bone of the human body, the humerus, the ray, and others. The walls of such bones are formed by a compact substance. Its structural unit is an osteon consisting of specialized bone plates. The head of long bones consists of a spongy substance, between the particles of which is a red bone marrow - one of the blood-forming structures of the body.

Short bones are the vertebrae, wrists, plus. And examples of wide are the scapula and pelvic bones. They are formed predominantly by a spongy substance.

Regardless of the structure, each bone is covered from above with a layer of connective tissue - the periosteum.

The best

The structure of the tubular bone determines its title of the most durable and longest. But the shortest is the auditory ossicle - the stirrup. Its length does not exceed 3.5 mm. The strongest bone is the jawbone.

Surprise the bones and their number. Imagine: a man's leg consists of 52 bones. This is almost a quarter of their total. An interesting fact is that the number of bones decreases with age. Thus, a newborn child has about 300, and in an adult this figure barely reaches 206. This is because over time, some bones, for example skulls, grow together.

Growth of bones

Man is born on light with a skeleton, in the structure of which the cartilaginous tissue predominates . Its transformation into bone continues on average to 20-24 years. Further, the processes of their growth stop. Therefore, many doctors advise themselves to engage in many sports at an early age, when the skeleton is still quite elastic. Microscopic structure of the bone allows you to draw conclusions, due to which elements are their growth. The inner layer of the periosteum provides an increase in thickness. And the growth in length is due to the division of cells of the cartilaginous tissue located at the ends of the bones.

Structure and connection of bones

Each part of the human skeleton fulfills its functional duties. Therefore, the bones are connected in different ways. A fixed connection is called a seam. It is a structure in which the protrusions of one bone enter the indentations of another. So connect the bones of the skeleton of the head. At first glance, it may even seem that the skull consists of one solid bone. So perfect this connection. And it exists not accidentally, but in connection with the functional necessity. The skull protects the brain from mechanical effects during accidents. And only one of his bones is movable. This is the lower jaw.

Movable connection of bones is called a joint. It is thanks to these compounds that the movement of the organism and its separate parts occurs. What are the features of the structure of the bones of the joint? In particular, the fact that one head enters the recess of the other. In the places of contact they are covered with hyaline cartilage with a smooth surface. This structure helps reduce friction during movement.

An additional protection against stretching is the joint bag that surrounds it from the outside. Inside it is a special fluid, which also reduces friction. To the articular bag are attached muscles and ligaments, which lead directly to its movement.

Movable joints of bones differ an important characteristic feature. This is the number of axes of motion. For example, the knee joint is biaxial, and the hip joint allows you to do movements in three directions at once.

The backbone of a man has a completely different structure. Its individual bones are connected by cartilaginous layers. This is the semi-mobile connection of bones. Cartilage layers are capable of compression and stretching. They provide mobility of this part of the skeleton only within certain limits. However, such structures provide the effect of a shock absorber, softening shocks during sharp jumps and movements.

Structure of the human skeleton

The skeleton as a basis of the musculoskeletal system consists of several parts. The skeleton of the head, or skull, is conditionally divided into two parts: the brain and facial. The first person has the predominant size, which is associated with the development of the brain - the central part of the nervous system. The skeleton of the trunk unites the spine and thorax, which reliably protects the internal organs of the thoracic cavity. The number of vertebrae in the human body is 33-34. These are 7 cervical, 12 thoracic, 5 lumbar, 5 intertwined sacral, 4-5 coccygeal. The first two of them - the atlant and the epistrophe - are connected by means of a tooth-shaped process, due to which the head is able to move. By the way, the number of cervical vertebrae in all representatives of the class mammals is the same and equal to seven. This number has both an elephant and a field mouse. The difference is only in size.

The skeleton of the shoulder and pelvic girdle is represented by the clavicles and shoulder blades on top and the fused pelvic bones from below. They are attached free limbs: shoulder, forearm, hand, forming free upper limbs, as well as the thigh, shin and foot - lower, respectively.

Thus, the functions performed are determined by the structure of the elements of the musculoskeletal system: from the microscopic to the tissue and the level of the organs of the human body.