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Bone Response to Damage (view source)
Revision as of 13:53, 28 September 2007
, 13:53, 28 September 2007no edit summary
***Produce bone matrix = '''osteoid'''
***Produce bone matrix = '''osteoid'''
***Cell membranes are rich in alkaline phosphatase (ALP)
***Cell membranes are rich in alkaline phosphatase (ALP)
**'''Osteocytes'''
**'''Osteocytes'''
***Osteoblasts that have become surrounded by mineralised bone matrix
***Osteoblasts that have become surrounded by mineralised bone matrix
***Occupy cavities called '''lacunae'''
***Occupy cavities called '''lacunae'''
**'''Osteoclasts'''
**'''Osteoclasts'''
***Multinucleated cells
***Multinucleated cells
***Derived from haematopoietic stem cells
***Derived from haematopoietic stem cells
***Responsible for bone resorption (have a brush border for this)
***Responsible for bone resorption (have a brush border for this)
*'''Matrix'''
*'''Matrix'''
**Type I collagen forms the backbone of the matrix
**Type I collagen forms the backbone of the matrix
===Bone organisation===
===Bone organisation===
*Patterns of collagen deposition:
**'''Woven bone''':
***"Random weave" which is only a normal feature in the foetus
***In adults it is a sign of a pathological condition (e.g. fracture, inflammation, neoplasia)
**Lamellar bone:
***Orderly layers which are much stronger than woven bone
***Two main types:
****'''Compact bone''' (cortical)
*****Forms 80% of total bone mass
*****Forms the shell of long bone shafts - contain '''Haversian systems'''
****'''Cancellous bone''' (spongy or trabecular)
*****In vertebrae, flat bones and epiphyses of long bones
*****Contains no Haversian systems
Periosteum and blood supply
===Periosteum and blood supply===
The periosteum is a specialised sheath of connective tissue covering bone except at the articular surfaces. The inner layer merges with the outer layer of bone and contains osteoblasts and osteoprogenitor stem cells.
The periosteum is a specialised sheath of connective tissue covering bone except at the articular surfaces. The inner layer merges with the outer layer of bone and contains osteoblasts and osteoprogenitor stem cells.