Laboratory work "Microscopic bone structure" is familiar to every student. Everyone remembers that it is precisely due 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.
The value of the musculoskeletal system
The system of organs of movement consists of bones, muscles and ligaments connecting them. This is a well-coordinated mechanism, thanks to which the body has a shape, its internal organs are significantly protected from mechanical damage, individual parts and the whole organism can move in space. How important is this feature? 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 movements towards the sun.
For the human body, this important function is provided by the structure of the skeleton bones.
Osteocytes
The microscopic structure of the bone is represented by its cells. They are called osteocytes. They have a fusiform or star shape, a large rounded core. Translated, the name of these cells means "bone."
In the cytoplasm of osteocytes, there are few permanent cell structures called organelles. If you examine them under a microscope, you can distinguish individual mitochondria and elements of the endoplasmic reticulum.
Bone cells have an important distinguishing feature. It lies in the fact that in an adult body that has formed, osteocytes lose their 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. Its characteristic feature is a large amount of intercellular substance into which individual cells are immersed.
Bone tissue is also arranged. Its intercellular substance is formed by minerals and collagen fibers, which are structures of protein nature.
Lab "Microscopic bone structure"
Consider this kind of fabric under high magnification. Visually, the microscopic structure of the bone resembles a network. Such a structure is formed due to the numerous thin outgrowths of osteocytes with which they connect together. Such a network gives the bones strength. Due to the presence of collagen fibers, which include contractile proteins, the bones are capable of compression and stretching.
The microscopic structure of the bone illustrates very well below.
Bone chemistry
25% of the total composition of substances is water. The same percentage is attributable to organic matter. Basically it is an elastic collagen protein having a fibrous structure. It gives bones such a property as elasticity. For example, the structure of the tubular bone allows it to withstand a load of 1.5 tons. Minerals are represented mainly by salts of phosphorus and calcium. Their function is to provide bone hardness and strength. 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 experiences
The microscopic structure of the bone has its own characteristics. But which 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 minerals dissolve. The bone becomes so flexible that it can easily be tied into a knot. But then our body would not have a foundation and support.
If you bake the bone on a very slow fire, all organic substances will gradually oxidize. As a result, such fabric can simply crumble.
There is only one conclusion: each group of substances gives the bones certain properties, making this tissue unique and indispensable for the human body.
Bone classification
Depending on the shape, several groups of bones are distinguished. Long, which are also called tubular, form a cavity inside. It is filled with a special substance - yellow bone marrow. It is rich in adipose tissue, nourishes bones, and also plays an important role in metabolic processes. Such bones, due to the structural features, combine strength and lightness. Their examples are the femur - the longest bone of the human body, the humerus, beam, 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 heads of long bones consist of a spongy substance, between the particles of which there is a red bone marrow - one of the hematopoietic structures of the body.
Short bones are the vertebrae, wrists, metatarsus. And examples of the wide ones are the scapula and pelvic bones. They are formed mainly by spongy matter.
Regardless of the structure, each bone on top is covered with a layer of connective tissue - the periosteum.
The best
The structure of the tubular bone determines its title of the strongest and longest. But the shortest is the auditory ossicle - the stirrup. Its length does not exceed 3.5 mm. The strongest bone is the jaw bone.
Surprise bones and their quantity. Imagine: a man’s leg consists of 52 bones. This is almost a quarter of their total number. An interesting fact is that with age, the number of bones decreases. So, in a newborn child there are about 300, and in an adult, this figure barely reaches 206. This is due to the fact that over time, some bones, such as skulls, grow together.
Bone growth
A person is born into the world with a skeleton, in the structure of which cartilage tissue predominates . Its transformation into bone continues on average up to 20-24 years. Further, their growth processes stop. Therefore, doctors advise to engage in many sports at an early age, when the skeleton is still quite elastic. The microscopic structure of the bone allows us to draw conclusions on which elements they grow. The inner layer of the periosteum provides an increase in thickness. And the growth in length occurs due to the division of cartilage tissue cells located at the ends of the bones.
The structure and connection of bones
Each part of the human skeleton performs its functional duties. Therefore, the bones are connected in different ways. A fixed joint is called a seam. It is a structure in which the protrusions of one bone enter the recesses of another. So the bones of the skeleton of the head are connected. At first glance, it may even seem that the skull consists of one solid bone. So perfect is this mix. And it does not exist by chance, but in connection with functional necessity. The skull protects the brain from mechanical stress during accidents. And only one of his bones is connected movably. This is the lower jaw.
The movable joint of the bones is called the joint. It is thanks to these compounds that the movement of the organism and its individual parts takes place. What are the structural features of the joint bones? In particular, the fact that one head enters the recess of the other. In places of contact, they are covered with hyaline cartilage with a smooth surface. This structure helps to reduce friction during movement.
An additional protection against stretching is the articular bag, which surrounds it outside. Inside it is a special fluid that also reduces friction. Muscles and ligaments are attached to the joint bag, which directly drive it.
Mobile joints of bones are distinguished by an important characteristic feature. This is the number of axes of movement. For example, the knee joint is biaxial, and the hip allows you to make movements in three directions at once.
A completely different structure has the human spine. Its individual bones are connected by cartilaginous layers. This is a semi-mobile connection of bones. Cartilaginous layers are capable of compression and stretching. They provide mobility of this part of the skeleton only within certain limits. However, such a structure provides a shock absorber effect, softening tremors during sharp jumps and movements.
The structure of the human skeleton
The skeleton as the basis of the musculoskeletal system consists of several parts. The skeleton of the head, or skull, is conditionally divided into two departments: cerebral and facial. The first in humans has predominant dimensions, which is associated with the development of the brain - the central part of the nervous system. The skeleton of the trunk combines the spine and chest, which protects the internal organs of the chest cavity. The number of vertebrae in the human body is 33-34. These are 7 cervical, 12 thoracic, 5 lumbar, 5 sacral fused, 4-5 coccygeal. The first two of them - the atlas and epistrophy - are connected with the help of the tooth-like 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. Such an amount 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 collarbones and shoulder blades from above and fused pelvic bones from below. Free limbs are attached to them: the shoulder, forearm, hand, forming the free upper limbs, as well as the thigh, lower leg and foot - lower, respectively.
Thus, the functions performed are determined by the structure of the elements of the musculoskeletal system: from microscopic to tissue and the level of organs of the human body.