Histology of Bone Tissue
Composition of bone tissue matrix;
20% water, 50% mineral salts, 30% protein fibers.
1. Bone matrix
2. Bone cell
1. Bone matrix
Bone is made up of bone matrix.
Bone matrix is composite material consisting of;
a.Organic material (35%); growth factor
Consist of;
Collagen; fibrous protein
Proteoglycans; protein
b. Inorganic material (65%); bone minerals
Primarily consists of calcium phosphate.
Collagen and mineral component; major component responsible for functional characteristics of bone.
If entire mineral is removed from long bone, collagen become primarily constituents, bone become flexible.
If collagen is removed from bone, minerals component become primarily constituents and bone is hard but easily broken.
Bone Composition
1. Bone matrix
2. Bone cell
1. Bone matrix
a. Organic; collagen, proteoglycans
b. Inorganic; calcium, phosphorus
2. Bone cell
1. Osteogenic cell
2. Osteoblast
Blast;create matrix
3. Osteocytes
Cytes; maintain matrix
4. Osteoclast
Clast; Break it down for remodeling
2. Bone cell
1. Osteoprogenitor/ osteogenic cells
Derived from mesenchymal (embryonic).
Found in deepest layer of periosteum and in endosteum and in canals (perforating and central) in bone that contain blood vessels.
Have mitotic potential, can transformed into bone forming cells (oesteoblasts) during healing.
2. Osteoblasts
Bone formation; growing portion of bones, including periosteum and endosteum.
Osteoblast are mononucleated bone forming cells.
These are immature bone cells.
Oesteoblasts are bone building cells that form bone.
Lost ability to divide by mitosis.
Found in growing portion of bone.
These cells synthesizes and secrete unmineralized ground substance called osteoid, contains collagen.
When calcium salts deposited in fibrous osteoid, osteoid calcifies into bone matrix.
Oesteoblasts initiation calcification.
3. Osteocytes
Osteocytes are main cells of fully developed bones or mature bone cells that are derived from osteoblasts, that secreted, bone tissue.
Osteoblast are found on surfaces of bone but they surround themselves with matrix materials, become osteocytes.
Osteocytes have no mitotic potential.
Oesteocytes keep matrix in stable and healthy state by secreting enzymes and maintaining it's mineral content.
Osteocytes, a cell that lies within substance of fully formed bone.
It occupies small chamber called lacuna, contained in calcified matrix of bone.
Cytoplasmic processes of osteocyte extend away from cell toward other osteocytes in small channel called canaliculi.
By canaliculi nutrients and waste product are exchanged with blood.
Osteogenic cell - osteoblasts- osteocytes- osteoclasts
Develops into osteoblast - forms bone tissue; bone formation- maintain bone matrix; maintain mineral concentration of matrix - Bone resorption (osteoclasts break down tissue in bone and release release minerals.
4. Osteoclasts
Osteoclasts are multinuclear cells.
Osteoclasts are cells that degrade bone to initial normal bone remodeling. (bone reabsorbing cells).
Developed from monocytes.
Function
Bone resorption (dissolving and assimilation) to maintain optimum shape destruction of bone matrix.
Bone resorption important in development, growth, maintenance and repair of bone, healing of fracture.
Under periosteum remove excess callus during healing of fracture bone.
0 Comments