Microstructure of bone Flashcards
What is the main type of collagen in bone
Type 1
What forms the osteoid
Non- collagenous proteins and ground substances (glycoproteins and proteoglycans)
Formula of hydroxyapatite
Ca10(PO4)6OH2
When does the notochord develops
3rd week after conception
When are the first signs of arms and legs
4th week after conception
When do the first bone cells appear
8th week after conception
Function of bone
Protection Support - produce max strength with min material and to resist max compressional stress Movement Reservoir - for essential minerals Blood cell formation
Cortical bone
80% skeletal mass
Compact or lamellar bone
Mature form of bone
Bundles of collagen fibres in the bone matrix are organised into successive sheets and in same direction
Is cortical bone remodelled from woven bone
Yes
Woven bone is also known as immature bone
What is the primary structure of the cortical bone
Osteon
Also known as Haversian system
What is the outside bone
Cortical bone - solid bone
What is the inside bone
Trabecular bone - spongy, elastic bone
Trabecular bone
20% skeletal mass
Less dense, elastic, higher turnover rate than cortical bone
Contributes most of the bone tissue of the axial skeleton
Where is woven bone formed
During embryonic development, fracture healing and in some pathological sites
Randomly arranged collagen bundles
Normally remodelled in cortical or cancellous bone except in a few places where woven bone persists - where tendons insert into bones and the tooth sockets
What is external bone covered by
Periosteum - covers and protects the outer surface of bones that are not covered by cartilage
Double membrane of periosteum
Outer fibrous layer - dense irregular connective tissue. protective layer
Inner layer - Delicate osteogenic layer, contains mainly osteoblasts and osteoclasts
What are osteoblasts and osteoclasts
Osteoblasts = bone forming cells Osteoclasts = bone destroying cells
How is periosteum anchored to bone
Sharpeys fibres (strands of collagen fibres)
What is internal bone covered by
Endosteum
Osteogenic membrane - delicate connective membrane containing mainly osteocytes and osteoclasts
What are the two types of ossification
Intramembranous - replacement of thin c.t membrane with bone - flat bones
Endochondral - replacement of fetal cartilage skeleton with bone - long, irregular and short bone
Osteoblasts, clasts and cytes
Osteoblasts - form the collagen, glycoproteins and proteoglycans of the matrix, control the deposition of mineral crystals on the fibrils (MAKE)
Osteocytes - Maintaining the matrix of its territory. (MAINTAIN)
Osteoclasts - Very lage, multi nucleated, bone resorbing cells (RESORB/ DESTROY)
Mineral contents
Alveolar bone - 70% (inorganic) Cementum - 70% (inorganic) Dentine - 70% (inorganic) Enamel - 96% (inorganic) Pulp - none
What is bone homeostasis
Bone resorption and formation are balanced allowing for continual renewal of skeletal tissue and repair of micro damage
