The human skeleton consists of more than 200 bones. All of them perform a specific function, in general, creating support for external and internal organs. Depending on the load and role in the body, there are several varieties of them.
Structure of bones
In dry form, human bone is 1/3 composed of organic matter - ostein protein. It provides its flexibility and elasticity. 2/3 are inorganic calcium s alts, due to which their strength is achieved.
The outer shell is the so-called compact substance. These are dense scales of bony tissue. Their densest layer can be observed in the center of tubular bones. Towards their edges, the compact substance becomes thinner.
Depending on the type of bones, their inner part may consist of either a spongy substance or white marrow, or may be filled with air. Spongy bones, in addition, also have red bone marrow.
The ends of the bone include nerves and blood vessels that connect it to the rest of the body and provide nutrition, growth and repair.
Varieties of human bones
The structure of the bones are divided intosponge, tubular and pneumatic. Tubular is also called long. They are present in the skeleton of the limbs and are responsible for their movement. These bones consist of a compact substance and a cavity filled with yellow marrow. At the ends they have a little spongy substance filled with red bone marrow.
Human spongy bones are made entirely of spongy matter with red marrow inside, they are covered with a compact substance. They form cavities (thoracic, cranial) and serve as a support in places with the greatest load (spine, phalanges).
Pneumatic bones have a special structure: inside the compact substance there is a cavity filled with air and filled with epithelium. An example is the skeleton of the upper jaw.
Spongy bones: detailed diagram
As already noted, at its core, the structure of the cancellous bone is practically the same as the others. This is a cavity formed by a compact substance and filled with spongy. They are different in origin. The bones of the ribs, for example, are formed from cartilage, and the lids of the skull are formed from the connective tissue.
The spongy substance consists of many thin bony partitions, directed in accordance with the movement of substances in the bone. This structure allows you to achieve greater strength from the bones. They are less likely to break and crack.
At the edges of the bones is cartilage, through which nutrients enter and nerve endings penetrate.
Spongy substance cavities filled with redbone marrow responsible for the formation of red blood cells. Such a scheme of spongy bone allows it to perform several very important functions at once.
Varieties
In the structure of the human skeleton, spongy bones have a quantitative advantage. Therefore, scientists distinguish several of their varieties.
Distinguish between flat and voluminous bones. Flat ones form a cover of the cranium and pelvic cavity. This includes the blades. Volumetric are represented by ribs and phalanges of the fingers. The vertebrae are classified as a mixed type, since their body consists of a voluminous tubular bone, and the process is flat.
It is customary to distinguish long and short spongy bones by size. The ribs are considered one of the longest. The bones of the phalanges of the fingers and toes belong to the short ones.
The scapula can be called a unique bone. It is attached to the body only with the help of connective tissues, while most bones are connected by joints.
Functions of spongy bones
The first and main function that spongy bones perform is supporting. They form the basic frame of the human skeleton. The vertebrae form the spine, which supports the entire body in an upright position. The bones of the foot support the entire weight of the body.
The second function is protective. Spongy human bones create and surround cavities, protecting their contents from external damage. These are the skull cap, ribs and pelvic bones.
The motor function is carried out by the bones of the phalanges of the toes and hands.
When metabolic disorders occur, bones can become very brittle or extremely strong. In both cases, it is dangerous for normal human life.
Internal filling of bones - bone marrow - plays a major role in the formation of blood.
Meaning of red bone marrow
In the human body, the scheme of spongy bone implies the mandatory presence of red bone marrow in it. This substance is so important for life that it is present even in tubular bones, but in smaller quantities.
In childhood, spongy and tubular bones are equally filled with this substance, but with age, the tubular cavities are gradually filled with fatty yellow bone marrow.
The main task of the red bone marrow is the synthesis of red blood cells. As you know, these cells do not have a nucleus and cannot divide themselves. In spongy matter, they mature and enter the bloodstream during bone metabolism.
Impaired functioning of the red bone marrow leads to diseases such as anemia and blood cancers. Often, drug treatment is not effective and one has to resort to a red brain transplant.
This substance is very sensitive to radiation. Therefore, many victims of it have precisely various forms of blood cancer. The same property is also used in transplantology when it is necessary to kill infected bone marrow cells.
Possible damage
By nature, the structure of spongy boneallows it to be quite resistant to mechanical damage. But there are often times when the integrity of the bone is broken.
Compression fractures are characterized by compression of the bone due to a strong impact on it. The vertebrae are very susceptible to this type of damage. You can get injured during an unsuccessful landing on your feet or a fall. The danger of a fracture is that the vertebra ceases to protect the spinal cord, which can lead to damage.
Because most long spongy bones are curved, they can crack when struck hard against hard objects. Such damage is relatively harmless. With timely medical care, the cracks heal quite quickly.
Can spongy bones and break. In some cases, injuries of this kind are practically not dangerous. If there was no displacement, they are restored quite quickly. The danger is those bones that, when fractured, can move and pierce vital organs. In this case, a relatively harmless fracture causes disability and death.
Bones and aging
Like all other human organs, spongy bones are subject to age-related changes. At birth, some of the future bones either did not get stronger or were not formed from cartilage and connective tissues.
Over the years, the bones tend to "dry out". This means that in their composition the amount of organic substances becomes smaller, while mineral substances replace them. Bones becomefragile and take longer to recover from damage.
The amount of bone marrow is also gradually decreasing. Therefore, the elderly are prone to anemia.
