Lecture 3 - Bone And Tooth Structure Flashcards Preview

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Flashcards in Lecture 3 - Bone And Tooth Structure Deck (19):
1

Bone mineral is

Calcium and phosphate laid down as hydroxyapetite crystal

- gives compressive strength

2

What has a high proportion of trabecular bone

Spine + pelvis

3

What has a high proportion of cortical bone

Bones of arm, femur

4

Bone matrix composition

COLLAGEN
- gives tensile strength
- type I

NON COLLAGENOUS PROTEINS
- alkaline phosphatase
- proteoglycans
- growth factors in bone matrix

BONE MINERAL

5

Osteoblasts

- bone forming cells
- line bone surface
- active synthesis of matrix
- involved in mineralisation

6

Lining cells

- flattened osteoblasts lining bone surface

7

Osteocytes

- osteoblasts embedded in bone matrix
- connected by canaliculae
- involved in sensing mechanical forces
- make up 90% of bone cells and are long lived

8

Bone resorbing cells: osteoclasts

- multinucleated giant cells
- secrete acid and proteolytic enzymes
- dissolve mineral and degrade protein
- release embedded growth factors

9

Activity of osteoblasts or osteoclasts depends on

- number of cells formed
- activity of cells
- lifespan of cells

10

3 reasons why bone turnover happens

- shape changes of bone
- in response to changing load
- repair of microdamage

11

Osteoclast induced osteoblast differentiation

Osteoclast release TGFb, BMP and IGF during resorption, which induces chemotaxis, proliferation and differentiation of osteoblasts, leading to mineralization

12

Osteoblast-induced osteoclast differentiation

Osteoblast express RANK-L on their surface
- binds to RANK ligand on a preosteoclast
- this interaction results in osteoclast differentiation

- osteoblasts can also produce osteoprotegerin to prevent this interaction

13

Tooth specialized cells

- Ameloblast: lay down enamel, very dense matrix resistant to acid attack. Closely packed collagen and HAP crystals

- Odontoblasts: lay down dentine. Collagen fibres in dentine extend to alveolar bone

- osteoblasts and osteoclasts involved in alveolar bone remodeling

14

Caries

Bacteria + food -> anaerobic acid release -> dissolves mineral
- also proteolytic enzymes -> break down matrix

15

Assessing bone: bone densitometry

- assume normal mineralisation
- no osteophytes
- consider aortic calcification

16

Other methods of assessing bone

- ultrasound
- bone biopsy - very invasive
- other: bone quality - microarchitecture/fractures/ cell death/ rates of bone turnover

17

Osteoporosis

- low trauma fracture
- bone mineral density

18

T score and Z score

- T score: compared with mean peak bone mass - assesses what is desirable, used to assess fracture risk

- Z score: compared with age and gender matched controls - assesses what is expected. USed to determine if bone mass is unusually low

19

T score and disease category

Normal: -1 and above
Osteopenia: -1- - 2.5
Osteroporosis: