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BDS2 BAMS oral biology > bone & cartilage > Flashcards

Flashcards in bone & cartilage Deck (43)
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1
Q

describe cortical (compact) bone

A

dense outer plate

80-85% of skeleton

2
Q

describe cancellous (spongy) bone

A

internal trabecular scaffolding

15-20% of skeleton

3
Q

describe alveolar bone

A

cortical bone has nutrient canals, containing b.v.

cortical bone lining tooth sockets is penetrated by bundles of collagen fibres of PDL

4
Q

what is the composition of bone?

A

60% inorganic -HA
25% organic
15% water

5
Q

what is the organic component made of?

A

collagen
glycoproteins
proteoglycans

6
Q

what are the 2 components of the extracellular matrix?

A

ground substance

fibres

7
Q

describe ground substance?

A

semi-fluid gel
long polysaccharide molecules
glyco-amino-glycans

8
Q

what are the 2 GAG’s?

A

hyaluronic acid

proteoglycans

9
Q

what fibres are in the ECM?

A

collagen
elastin
other non-collagenous proteins

10
Q

what is the function of fibres in ECM?

A

reinforce extracellular ground substance

11
Q

what are the 2 types of microscopic bone?

A

woven and lamellar

12
Q

describe woven bone

A
rapidly laid down
irregular deposition of collagen
present in fetus
fracture repair
contains many osteocytes
13
Q

describe lamellar bone

A

laid down more slowly
collagen fibres laid down in parallel
normal form in adults
contains fewer osteocytes

14
Q

what is the structure of compact bone?

A
laid down in concentric lamellae
form longitudinal columns
organised in haversian systems around central canal
lateral canals
canals contain b.v
15
Q

describe the structure of cancellous bone

A
network of thin traveculae
trabeculae consist of lamellae
osteocytes present
no obvious haversian systems
thin bone nutrients can diffuse
bone marrow present in spaced between trabeculae
16
Q

describe osteoblasts

A

lie on surface of bone
derived from mesenchymal stem cells
synthesise and secrete collagen fibres forming a matrix
matrix mineralised by ca salts

17
Q

describe osteocytes

A

osteoblasts that become trapped in mineralised bone
lie within spaces- lacunae
contact other osteocytes via cytoplasmic processes that run in canaliculi
osteocytes also appear to communicate with osteoblasts

18
Q

describe osteoclasts

A

large multinucleate cells derived from haemopoietic stem cells
related to macrophages
resorb bone
lie in concavities in bone

19
Q

describe bone remodelling (turnover)

A

removal and replacement of bone tissue without change in shape
resorption balanced by deposition
each year 2% cortical, 25% cancellous
controlled by osteoblasts

20
Q

how is bone remodelling regulated?

A

hormones
-PTH, calcitonin
paracrines

21
Q

what is the reversal line?

A

scalloped edge shows where bone resorption changes to bone deposition

22
Q

when do tooth movements occur?

A

during eruption
post-eruptive eg mesial drift
orthodontic forces

23
Q

what do tooth movements require?

A

remodelling of adjacent soft and hard tissues

24
Q

what is cartilage?

A

semi-rigid, unmineralised CT

25
Q

what is in the cartilage matrix?

A

ground substance

fibres

26
Q

describe hyaline cartilage

A

widespread

larynx, nasal septum, trachea, ends of ribs, articular surfaces, embryonic skeleton

27
Q

where is fibrocartilage found?

A

intervertebral discs

pubic symohysis

28
Q

where is elastic cartilage found?

A

external ear, epiglottis, eustacian tube

29
Q

what are cartilage cells formed by?

A

chondoblasts

30
Q

how are chondrocytes formed?

A

chondroblasts get trapped in the matrix and become chondrocytes

31
Q

describe chondrocytes

A

avascular
nutrient diffuses in
some channels are present in thick areas of cartilage
contain stores of lipid and glycogen

32
Q

what are the 2 types of bone growth?

A

endochondral ossification

intramembranous ossificaiton

33
Q

describe endochondral ossification

A

long bones
cartilage precursor
cartilage proliferation
cartilage replaced with bone

34
Q

describe intramembranous ossification

A

flat bones
bone formed de novo in CT
no cartilage precursor

35
Q

what kind of bone growth occurs in the skull?

A

intramembranous ossification

36
Q

is there cartilage in skull?

A

no

37
Q

what areas of bone is there no calcification?

A

epiphysial

38
Q

when does epiphysial ossification begin?

A

when bone reaches final size

39
Q

what is the spheno-occipital synchondrosis?

A

special bone with mix of intramembranous and endochondral ossification
base of skull
no flexibility

40
Q

what is achondroplasia?

A

limited growth on base of skull
spenoid bone not growing properly
maxilla & mandible normal

41
Q

what kind of bone growth is the condyl?

A

endochondral

42
Q

what allows epiphysial growth in the TMJ?

A

fibrocartilaginous zone

43
Q

how does the mandible structure change over time?

A

condyl over lifetime
articular emenants flat in children
alceolar if teeth removed