Bone

Question 1

What are the functions of bone?

Answer 1

Weight bearing/support
Protection
Mineral store
Blood formation

Question 2

What is the gross anatomy of bone?

Answer 2

• Compact bone
• Spongy (trabecular) bone
• Blood vessels
• Medullary cavity
• Bone marrow
• Membranes (periosteum/endosteum)

Question 3

What is compact bone organised into?

Answer 3

Circular structures known as osteons surrounding a central Haversian canal

Question 4

What canals run horizontal in bone?

Answer 4

Volkmann’s canals

Question 5

What is found around a Haversian canal?

Answer 5

Osteocytes and concentric ring of bone matrix known as lamellae

Question 6

What are other names for spongy bone?

Answer 6

• Cancellous
• Trabecular bone
• Diploe

Question 7

What is spongy bone?

Answer 7

A network of lamellated trabeculae filled with bone marrow

Question 8

What does the orientation of trabeculae reflect?

Answer 8

The main directions of mechanical forces

Question 9

What are the 6 types of bone?

Answer 9

Flat bone
Sutural Bone
Long Bone
Sesamoid
Irregular Bone
Short Bone

Question 10

What are the 2 types of bone development?

Answer 10

• Endochondral

- Intramembranous

Question 11

What is the primary ossification centre?

Answer 11

Where bone formation begins

Question 12

Where does intramembranous ossification also occur?

Answer 12

Adult cortical bone

Question 13

What makes up bone?

Answer 13

• Cells (osteoblasts, osteoclasts, osteocytes)

- Extracellular matrix (hydroxyapatite crystals, Type 1 collagen, water)

Question 14

What do minerals such as hydroxyapatite do in bone?

Answer 14

Make bone stiff and able to support structures as they have high strength under compression

Question 15

What does collagen do in bone?

Answer 15

Gives bone some flexibility and reduces risk of fracture as it has high strength under tension

Question 16

What makes bone healthy?

Answer 16

Having a constant balance between bone removal and bone formation

Question 17

What are osteoblasts?

Answer 17

Immature bone cells created from ostopregenitor cells in the periosteum and endosteum

Question 18

What is the function of osteoblasts?

Answer 18

To produce bone matrix and initiate calcification

Question 19

What happens to osteoblasts once they are surrounded by matrix?

Answer 19

They become osteocytes

Question 20

What are osteocytes?

Answer 20

Mature bone found inside lacunae

Question 21

What do canaliculi do?

Answer 21

Connect lacunae to each other to allow communication between cells

Question 22

What are osteoclasts?

Answer 22

• Multinucleate cells derived from monocytes/macrophages

- They are large cells with rough borders

Question 23

Where are osteoclasts found?

Answer 23

On the bone surface

Question 24

What is the function of osteoclasts?

Answer 24

To resorb bone matrix

Question 25

What are Howship’s lacunae?

Answer 25

Resorption pits

Question 26

What is the extracellular matrix?

Answer 26

It is mainly minerals, protein and water

Question 27

What kind of collagen is found in the extracellular matrix?

Answer 27

Modified type 1

Question 28

How is the collagen in the extracellular matrix arranged?

Answer 28

Strongly cross-linked and large gaps within fibres

Question 29

What do the gaps in the collagen fibres do?

Answer 29

Provide space of hydroxyapatite crystals

Question 30

What is the orientation of collagen fibres linked to?

Answer 30

Mechanical forces

Question 31

Name 3 disorders of bone remodelling.

Answer 31

Osteoporosis
Paget’s Disease
Osteopetrosis

Question 32

What happens in osteoporosis?

Answer 32

Resorption>Formation

Question 33

What happens in Paget’s Disease?

Answer 33

Increased Resorption/ Formation

Question 34

What happens in osteopetrosis?

Answer 34

Decreased resoprtion

Question 35

What is bone mass controlled by?

Answer 35

Genes and the environment

Question 36

What can cause significant bone loss?

Answer 36

Weightlessness or bed rest

Question 37

What is particularly effective in maintaining bone mass density?

Answer 37

Resistance and high impact sports