Bone structure, formation, growth, and repair

Question 1

What type of tissue is bone?

Answer 1

Specialised connective tissue

Question 2

Which material gives bone its rigidity?

Answer 2

Hydroxyapatite crystals (calcium + phosphate)

Question 3

Which material gives bone its resilience?

Answer 3

Type I collagen fibres

Question 4

In long bones, what is the long central part, which houses the medullary cavity, called?

Answer 4

Diaphysis

Question 5

In growing bones, which section of bone contains the epiphyseal growth plate?

Answer 5

Metaphysis

Question 6

Which structure lines the medullary cavity?

Answer 6

Endosteum

Question 7

Which structure provides blood vessels, nerves, and lymphatics to bone?

Answer 7

Periosteum

Question 8

What are the 2 layers of the periosteum?

Answer 8

Outer fibrous layer
Inner cellular layer

Question 9

Where on bones is the periosteum absent?

Answer 9

Articular cartilage

Question 10

On which type of bones is periosteum absent?

Answer 10

Sesamoid bones, such as the patella

Question 11

What are the immature and mature forms of bone tissue?

Answer 11

Woven bone
Lamellar bone

Question 12

Describe the difference in the arrangement of collagen fibres in woven and lamellar bone.

Answer 12

Woven - collagen fibres arranged randomly

Lamellar - collagen fibres orderly and parallel arrangement

Question 13

Lamellar (mature) bone can be categorised into which 2 types of bone?

Answer 13

Trabecular (spongy) bone

Cortical (compact) bone

Question 14

Which type of bone contains osteons?

Answer 14

Cortical (compact) bone

Question 15

What is the primary structural unit of cortical bone?

Answer 15

Osteons (Haversian systems)

Question 16

Which central canal in osteons contains blood vessels?

Answer 16

Haversian canals

Question 17

Which canal in osteons connects blood vessels to adjacent osteons and runs perpendicular to Haversion canals?

Answer 17

Volkmann’s canals

Question 18

In osteons, what remnants are the result of bone remodelling?

Answer 18

Interstitial lamellae

Question 19

Trabecular bone contains which type of bone marrow?

Answer 19

Red bone marrow

Question 20

Which type of bone remodels more rapidly in response to stress - cortical or trabecular?

Answer 20

Trabecular

Question 21

What is the arrangement of cortical and trabecular bone in flat bones?

Answer 21

Trabecular bone is sandwiched inbetween 2 layers of cortical bone

Question 22

Osteoprogenitor cells are derived from what?

Answer 22

Mesenchymal stem cells

Question 23

Osteoprogenitor cells differentiate into what?

Answer 23

Osteoblasts

Question 24

Raised ALP can indicate increased activity of which bone cell?

Answer 24

Osteoblasts

Question 25

What are the 3 key secretions of osteoblasts?

Answer 25

Osteoid ALP RANKL

Question 26

When osteoblasts become trapped in the mineralised matrix, they mature into what?

Answer 26

Osteocytes

Question 27

What are the spaces called which osteocytes occupy?

Answer 27

Lacunae

Question 28

List 3 functions of osteocytes.

Answer 28

Matrix maintenance Mechanotransduction Calcium and phosphate homeostasis

Question 29

What are osteoclasts derived from?

Answer 29

Haematopoietic stem cells (monocyte lineage)

Question 30

Which type of bone cell is multi-nucleated?

Answer 30

Osteoclasts

Question 31

When osteoclasts break down the ECM, which component breaks down organic material?

Answer 31

Enzymes

Question 32

When osteoclasts break down the ECM, which component breaks down mineralised material?

Answer 32

Hydrochloric acid

Question 33

What is the effect of RANKL on bone resorption?

Answer 33

Promotes bone resorption

Question 34

What triggers osteoclast progenitors to differentiate into mature osteoclasts?

Answer 34

The binding of RANKL on osteoblasts to RANK on osteoclast progenitors

Question 35

What is the effect of osteoprotegerin on bone resorption?

Answer 35

Inhibits bone resorption

Question 36

Which cells secrete osteoprotegerin?

Answer 36

Osteoblasts

Question 37

What is the effect of parathyroid hormone on RANKL? On OPG? On bone resorption?

Answer 37

Stimulates RANKL production Inhibits OPG expression Promotes bone resorption

Question 38

What is the effect of oestrogen on OPG? On bone resorption?

Answer 38

Stimulates OPG expression Inhibits bone resorption / promotes bone formation

Question 39

What are the 2 types of bone formation / ossification processes?

Answer 39

Intramembranous ossification Endochondral ossification

Question 40

In intramembranous ossification, what does mesenchyme differentiate into?

Answer 40

Osteoblasts

Question 41

What is the key difference between intramembranous ossification and endochondral ossification?

Answer 41

Intramembranous ossification does not include a cartilage model, endochondral ossification does

Question 42

Which type of ossification occurs in the cranial bones, mandible, and clavicle?

Answer 42

Intramembranous ossification

Question 43

In endochondral ossification, what does mesenchyme differentiate into?

Answer 43

Chondroblasts

Question 44

The primary ossification centre in long bones forms in which section of the bone?

Answer 44

Diaphysis

Question 45

The seconary ossification centre in long bones forms in which section of the bone?

Answer 45

Epiphysis

Question 46

What are the 5 zones of the epiphyseal growth plate?

Answer 46

Zone 1 - Resting (quiescent) zone Zone 2 - Growth (proliferation) zone Zone 3 - Hypertrophic zone Zone 4 - Calcification zone Zone 5 - Ossification zone

Question 47

What is the epiphyseal growth plate made of?

Answer 47

Hyaline cartilage

Question 48

What is a fracture involving the epiphyseal growth plate called?

Answer 48

Salter-Harris fracture

Question 49

What are the 5 stages of fracture healing?

Answer 49

Haematoma Granulation tissue Fibrocartilginous callus Bony callus Remodelling

Question 50

During the granulation stage of fracture healing, which cells produce what?

Answer 50

Fibroblasts produce collagen

Question 51

During the fibrocartilaginous callus stage of fracture healing, which cells produce what?

Answer 51

Chondroblasts produce cartilage

Question 52

During the bony callus stage of fracture healing, osteoblasts produce which type of bone?

Answer 52

Woven bone

Question 53

What is the role of the epiphyseal growth plate?

Answer 53

Enables longitudinal growth of bones

Question 54

What type of ossification occurs in the epiphyseal growth plate?

Answer 54

Endochondral ossification

Question 55

Which receptor does osteoprotegerin bind to?

Answer 55

RANKL