1. Bone and Cartilage

Question 1

Macroscopic types of bone (2)

Answer 1

Cortical (compact) - 85% of skeleton

Cancellous (spongy) - §5% of skeleton

Question 2

Composition of alveolar bone (2)

Answer 2

Cortisol bone

With nutrients canals containing BVs

Question 3

What makes up ECM of bone

Answer 3

Ground substance

Question 4

Definition of ground substance

Answer 4

Semi-fluid gel

Question 5

Composition of ground substance (2)

Answer 5

Polysaccharides

Glycos-amino-glycans (GAGs) - hyaluronic acid, proteoglycans (chondroitin SO4)

Question 6

Microscopic types of bone (2)

Answer 6

Woven bone

Lamellar bone

Question 7

Features of woven bone (4)

Answer 7

Rapidly laid down
Irregular collagen deposition
Present in foetus/fracture repair
Contains many osteocytes

Question 8

Features of lamellar bone (4)

Answer 8

Laid down more slowly
Collagen fibres laid down in parallel
Normal form in adults
Contain fewer osteocytes

Question 9

Composition of compact bone (5)

Answer 9

Laid down in concentric lamellae
Forms longitudinal columns
Organised in Haversian systems around central canal
Contains lateral canals
Canals contain BVs

Question 10

Composition of cancellous bone (5)

Answer 10

Network of thin trabecular consisting of lamellae
Osteocytes present
No obvious Haversian system
Bone is thin, nutrients can diffuse in
Bone marrow present in space between trabeculae

Question 11

Where are osteoblasts found and what are they derived from

Answer 11

Surface of bone

Mesenchymal stem cells

Question 12

Function of osteoblasts

Answer 12

Synthesise and secrete collagen fibres which form a matrix

Question 13

How is this matrix mineralised

Answer 13

By calcium salts

Question 14

Definition of osteocyte

Answer 14

Osteoblasts that become trapped within mineralised bone

Question 15

Where are osteocytes found

Answer 15

Lie within spaces called lacunae

Question 16

How do osteocytes communicate

Answer 16

Via cytoplasmic processes that lie in canaliculi

Question 17

Definition of osteoclasts and where do they derive from

Answer 17

Large, multinucleate cells

Derived from haemopoietic stem cells

Question 18

Function of osteoblasts

Answer 18

Resorb bone

Question 19

Where are osteoclasts found

Answer 19

Concavities in bone (Howship’s lacunae)

Question 20

What do osteoclasts control

Answer 20

Bone remodelling (turnover)

Question 21

What is bone remodelling

Answer 21

Removal and replacement of bone without a change in overall shape

Question 22

How is bone remodelling regulated (2)

Answer 22

Hormones (PTH, calcitonin)

Paracrines (various cytokines)

Question 23

What is the reversal line

Answer 23

Histological feature

Scalloped edge shows where bone resorption changes to bone deposition

Question 24

What does tooth movement require

Answer 24

Remodelling of adjacent soft and hard tissues

Question 25

When do these movements occur (3)

Answer 25

During eruption During mesial drift (post-eruption) Orthodontic forces

Question 26

Definition of cartilage

Answer 26

Semi-rigid, unmineralised CT that contains a matrix similar to bone

Question 27

Types of cartilage (3)

Answer 27

Hyaline cartilage Fibrocartilage Elastic cartilage

Question 28

Location of hyaline cartilage (6)

Answer 28

``` Widespread Larynx Nasal septum Trachea Costal cartilage Articular surfaces Embryonic skeleton (precursor to bone) ```

Question 29

Location of fibrocartilage (2)

Answer 29

Intervertebral discs | Pubic symphysis

Question 30

Location of elastic cartilage (3)

Answer 30

External ear Epiglottis Eustacian tube

Question 31

What what cells are cartilage formed

Answer 31

Chondroblasts

Question 32

What are chondrocytes and what do they contain

Answer 32

Chondroblasts trapped in the matrix | Stores of lipid and glycogen

Question 33

Are cartilage cells vascular or avacular

Answer 33

Avascular

Question 34

Types of bone growth (2)

Answer 34

Endocondral ossification | Intramembranous ossification

Question 35

Features of endochondral ossification (4)

Answer 35

Long bones Cartilage precursor Cartilage proliferation Cartilage replaced with bone

Question 36

Features of intramembranous ossification (3)

Answer 36

Flat bones Bone formed de novo in CT No cartilage precursor

Question 37

How does cranial base growth occur

Answer 37

Endochondral ossification

Question 38

How does sphenoid bone growth occur

Answer 38

Endochondral and intramembranous ossification

Question 39

Definition of achondroplasia

Answer 39

Genetic defect of cartilage growth | Endochondral bone growth is impaired, intramembranous bone growth is unaffected

Question 40

How does the condyle grow

Answer 40

Endochondral ossification