Bone & Cartillage

Question 1

what are the two types of bone known as?

Answer 1

• cortical (compact) bone

- cancellous (spongy) bone

Question 2

what % of the skeleton does cortical bone make up?

Answer 2

80-85% of skeleton

Question 3

what % of skeleton does cancellous bone make up?

Answer 3

15-20% of skeleton

Question 4

what type of bone is the dense outer plate of bone composed of?

Answer 4

cortical bone

Question 5

what type of bone is the internal trabecular scaffolding composed of?

Answer 5

cancellous bone

Question 6

what is interesting about the cortical bone found in the alveolar bone?

Answer 6

• cortical bone has nutrient canals that contain blood vessels

Question 7

what occurs in the cortical bone lining tooth sockets?

Answer 7

the cortical bone lining tooth sockets is penetrated by bundles of collagen fibres of PDL (Sharpey’s fibres)

Question 8

what is the compositional makeup of bone (by weight)?

Answer 8

• 60% inorganic (hydroxyapatite)
• 25% organic (collage, glycoproteins, proteoglycans)
• 15% water

Question 9

what is the extracellular matrix?

Answer 9

• semi-fluid gel
• composed of long polysaccharide molecules
• also made up of glucose-amino-glycans (GAGs)
• contains fibres

Question 10

what are the main fibres found within the extracellular matrix?

Answer 10

• collagen

- elastin

Question 11

what can extracellular matrix also be referred to as?

Answer 11

ground substance

Question 12

what are examples of glycols-amino-glycans?

Answer 12

• hyaluronic acid

- proteoglycans

Question 13

what are the different structures of bone?

Answer 13

• woven bone

- lamellar bone

Question 14

what is woven bone?

Answer 14

• rapidly laid down bone
• irregular depostion of collagen
• present in foetus
• fracture repair
• contains many osteocytes

Question 15

what is lamellar bone?

Answer 15

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

Question 16

what bone structure contains more osteocytes, woven or lamellar?

Answer 16

woven bone

Question 17

explain the structure of compact bone & how it is laid down?

Answer 17

• laid down in concentric lamellae
• forms longitudinal columns
• organised in Haversian systems around central canal
• contains lateral Volkman’s Canals
• canals contain blood vessels

Question 18

what is a Haversian system also known as?

Answer 18

an osteon

Question 19

how can the structure of cancellous bone be described when it is formed?

Answer 19

• network of thin trabeculae
• trabeculae consist of lamellae
• osteocytes present
• no obvious Haversion systems
• the bone is thin

Question 20

what can occur in cancellous bone due to it being thin?

Answer 20

nutrients can diffuse in

Question 21

where are osteoblasts located on bone?

Answer 21

lie on surface of bone

Question 22

what cells are osteoblasts derived from (embryologically)?

Answer 22

mesenchymal cells

Question 23

what is the function of osteoblasts?

Answer 23

synthesise & secrete collagen fibres forming a matrix which is then mineralised by calcium salts

Question 24

where are osteocytes located?

Answer 24

lie within lacunae spaces

Question 25

what type of cells do osteoclasts derive from?

Answer 25

haemopoietic stem cells (related to macrophages)

Question 26

what is the function of osteoclasts?

Answer 26

they resorb bone

Question 27

where are osteoclasts found within bone?

Answer 27

lie in con cavities in bone known as Howship’s lacunae

Question 28

what is meant by bone turnover?

Answer 28

removal and replacement of bone tissue, without change in overall shape
- resorption balanced by deposition

Question 29

what is bone remodelling regulated by?

Answer 29

• hormones

- paracrines

Question 30

what is cartilage?

Answer 30

semi-rigid, unmineralised connective tissue

Question 31

what are the different types of cartilage known as?

Answer 31

• hyaline cartilage
• fibrocartilage
• elastic cartilage

Question 32

where is hyaline cartilage located?

Answer 32

• nasal septum
• larynx
• trachea
• ends of ribs (costal cartilages)
• articular surface
• embryonic skeleton (precursor to bone)

Question 33

where is fibrocartilage found?

Answer 33

• intervertebral discs

- pubic symphysis

Question 34

where is elastic cartilage located?

Answer 34

• external ear
• epiglottis
• Eustacian tube

Question 35

what cells form cartilage?

Answer 35

chondroblasts

Question 36

is cartilage vascular or avascular?

Answer 36

avascular

Question 37

what bones develop by endochondral ossification? how does this occur?

Answer 37

long bones

• cartilage precursor
• cartilage proliferation
• cartilage replaced with bone

Question 38

what bones develop by intramembranous ossification? how does this occur?

Answer 38

Flat bones =

• no cartilage precursor
• bone formed alone