Monday, November 5, 2012

veterinary online- bones


Bone structure and blood supply 
The osteology is the study of bones. All the bones that form the skeleton is the framework of the body, serves to support soft tissue and plays a protective role against certain viscera. Bone is living in perpetual redesign, even in adults
Description bones :There are three types of bone:
Long bones: the length is greater than the width and thickness.
A middle part, the body or shaft of the bone.
Two ends: the epiphyses.
Or large flat bones: the length and width are greater than the thickness.
Both sides.
Short bones: the length, width and thickness are approximately equal.

Bone structure

Bone structure

1)Bone tissue.
2)The bone cells .
3)The osteoblasts : bone forming cells: secrete collagen, a protein substance necessary for ossification.
4)The osteocytes : star-shaped cells with thin and long extensions combine the cells together These are mature bone cells.
5)The osteoclast : cells that destroy bone while osteoblasts rebuild parallel.
6)The osteogenic cells: which are formed from all tissues.
7)The bone ground substance : ossein and minerals.
8)The varieties of bone tissue 
9)The compact fabric : the basic substance is dense. It forms the outer layer of the bone, it covers the spongy tissue.
10)The spongy tissue : the basic substance is less dense, rich in fat and connective tissue cells in red marrow where blood cells form.

Structure of different bones

1)The shaft : made ​​of compact bone tissue
2)The cortical width of the hollow cylinder formed by the compact bone tissue.
3)The cavity or spinal canal : cavity dug into the shaft in the middle of the cylinder compact. 
4)The yellow bone marrow : mainly greasy tissue filled the medullary canal.
5)The epiphyses : formed of spongy tissue filled with red bone marrow. They have surfaces which articular cartilage can be linked to each other.
6)The metaphyses : segment of bone between the epiphysis and the diaphysis.
7)The periosteum : fibro-elastic membrane that envelops the entire bone except at joint surfaces and cartilage.
8)It contains many blood vessels and bone provides a portion of its feeder vessels.

Development and growth of bones

The development of bone

Bone development

The development of bone osteogenesis. Bone can be formed by two different processes:
Endochondral ossification or cartilage ossification : each bone is preceded by a cartilaginous. This draft was then invaded by blood vessels. There is destruction of cartilage cells by connective tissue cells which then produce bone. This ossification begins during intrauterine life. There for long bone diaphyseal ossification point and one or more epiphyseal ossification.
Ossification fibrous or ossification membrane : the cells of the connective tissue of the embryo form a blank conjunctiva future bone and they transform directly into bone cells or osteoblasts which will develop the final bone.
The increase in length : it is through the growth plate. The diaphysis of the bone under the action of cartilage increases in length until early adulthood. The growth rate is controlled by a hormone (STH somatotrophyne or secreted by the pituitary gland). The thyroid has an important role on growth.

The increase in thickness : it is done through the periosteum. The periosteum, the deep layer develops layers of bone. At the same time, there is an increase in the medullary canal. The bone material is destroyed by osteoclasts. The medullary bone preserves considerable robustness while lightening.

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