bone histology Flashcards
1
Q
what is the function of bones
A
- mechanical + metabolic function
- support
- protection
- movement
- encloses the bone marrow
- reservoir of calcium/phosphate
2
Q
describe compact bones
A
- circumferential lamella
- harversian lamellae
- osteon - describes unit of lamella
- central harvesian canal - has blood vessels and nerves
3
Q
what does osteon refer to
A
unit of lamella
4
Q
describe skeletal muscles
A
- cartilage + bones:
- specialised (modified) connective tissue
- connective tissue = cells + ECM (ground substance + fibres)
- bones = mineralised connective tissue
5
Q
describe osteoblasts
A
- derives from osteoprogenitor cell, primitave mesenchymaal cell]present in endosteum and periosteum
- lined up along the surface of bone matric
- narrow spindle shape when inactive (osteoprogentiors)
- large and broad spindle shape or cuboidal cells when active (osteoblasts) - nigger and more cuboidal = identify → produce bone matric
- syntehsis osteoif + mediate mineralitsartion
- TYPE I COLLAGEN - proteoglycan , matricellular glycoproteins
- responsible for deposition of inorganic component
6
Q
describe bone matrix / osteoid
A
- highly vascularised
- about 70% is in inorganc material
- calcium hydroxyapatite - most abundant
- bicarbonate
- citrate
- magnesium
- potassium
- sodium ions
- 30% organic components
- 90% collagen type I
- small proteoglycans
- osteocalcin + phosphatases promote calcification of the matrix
7
Q
describe osteocytes
A
- inactive osteoblasts
- entrapped in matrix around lacunae
- long dentrictic processes that occupy the canaliculi
- create connections between osteocytes
8
Q
describe osteoclasts
A
- derive from macrophafe-moncyte cell line
- phagocytic cells
- multinucleated
- essential for the bone turnover + bone remodelling
- blood-calcium homeostasis
- ruffled broder secretes organic acids dissolve the mineral component
- lysosomal proteolytic enzymes destroy the organic osteoid matrix
- found in resoprtion lacunae (or howship lacunae)
9
Q
describe bone structure
A
- woven bone - immature bone
- lamellar bone - mature bone
- type of lamellar bone:
- compact bones
- cacellous bone/spongy bone/trabecullae
- periosteum - outer fubrous CT layer
- endosteum - inner
10
Q
what is the name for mature bone
A
lamellar bone
11
Q
what is the name for immature bone
A
woven bone
