Bone

  • Tumors of bone tissue
  • The bone tissue is the basis of the skeleton of a man and vertebrates. Bone is a depot of mineral salts and participates in metabolism.
    Histology. Bone tissue develops in the embryo at the beginning of the 3rd month of fetal life, from the embryonic tissue of leaves (the mesenchyme)purchasing osteogenic properties, or it can develop at the site of the cartilage. The bone - a type of connective tissue. Cellular forms of it are osteocytes (in the growing bone - osteoblasts) cells with a large number of processes, immured into the intercellular substance containing large amounts of inorganic salts (mainly phosphate calcium). The intercellular substance bone permeated beams useinovich (kreeptonik) fibers, United the so-called osteomalacia. Around osteocytes it forms a capsule.
    The main link of bone formation is osteon - system of bone plates located around gaverova channel through which the blood vessels and nerves. Group astionov form larger, macroscopically distinguishable elements of bone tissue and bone crossbar. Very close location is formed compact bone substance. The rare location of the bars with large gaps between them, filled with bone brain, creates a structure spongy bone tissue.
    Gaverova channels by which the blood supply to the bone, in a compact substance tubular bones are located along the longitudinal the axis of the diaphysis. In the transverse direction are punching vascular channels linking gaverova channels with the periosteum.
    In accordance with the nature of the structure there are coarse-fibered and fine-fibrous, or lamellar bone. Coarse-fibered bone typical for the bones of the skeleton of the fetus; from lamellar bone built most of the bones in the adult.
    All the bones of the skeleton according to morphological characteristics and are organised into the following groups: 1) large and small tubular; 2) the spongy; 3) flat; 4) the bones of complex structures.
    Tubular bones have diaphysis and the epiphyses (joint departments). In diaphysis distinguish itself diaphysis, consisting of compact matter and containing medullar channel with bone marrow, and metavis - the part of the diaphysis, which was built as the epiphysis, mainly from the spongy bone tissue surrounded by a thin layer of compact bone. Some spongy bones (vertebrae, heel bone) have apophyses, who, like the epiphysis of the tubular bones, develop from a separate cores of ossification, subsequently merged with the bulk of the spongy bone. In the flat bones distinguish compact discs and the prisoner between them the spongy bone tissue.
    The basic properties of the supporting bone structure, the strength and elasticity due to the normal ratio of organic and inorganic substances; inorganic creates hardness, and organic - elasticity bone substance.
    Mineral salts bone (mostly calcium phosphate) are located between the fibers of organic matter in the form of small crystals. The extremely small size of the crystals with a large number create an extremely large square surface. Such conditions allow intensive adsorption of ions, mineral salts from the blood, then there is a possibility of active mineral metabolism. Normal functioning of the bone tissue is characterized by the state of equilibrium between creation and by natural loss of bone substance.
    The livelihoods of bone connected with the functions of other organs and anatomical and physiological systems of the body (the Central nervous system, endocrine glands, excretory organs and digestion). The bone tissue is very sensitive to all kinds of violations of the normal functioning of the body. Disbalance of vitamins in the body lead to diseases of the bone tissue (rickets, children scurvy). The excess of the normal mechanical load on the bone in some parts of the skeleton causes physiological (hypertrophy) or pathological its restructuring. On the activity of the bone is affected by chronic intoxication some chemical substances (fluorine and its compounds); insufficient intake of calcium in organism causes disease of the skeleton - the so-called osteodystrophies.
    Under pathological conditions in the bone tissue there are a variety of changes: violations safe for injuries defeat in inflammatory diseases, tumors (see below), degenerative and dysplastic processes and aseptic necrosis (see).
    Special manifestations of pathological conditions bone are all kinds of developmental anomalies and deformities.
    The upcoming changes in the bone tissue appear destruction and pathological reactive creation of new bone. Reactive bone formation in a variety of bone disease occurs mainly due to the periosteum and to a much lesser extent angosta - the inner zone of the cortical bone.
    Inflammatory diseases of the bone tissue is more likely to occur in the depth of the bone, the bone marrow and are accompanied by suppuration (see Osteomyelitis). Limited destructive inflammatory focus, in the absence of festering and without expressed reactive changes around it is called Ostia. When a close arrangement of Ostia to the bone surface is observed the reaction of the periosteum - osteoporotic (e.g. syphilis).
    Limited inflammatory focus in the cortical layer of diaphysis called cortical, and with obvious signs of sepsis - cortical abscess.