Bone

Question 1

What are the three main functions of bone?

Answer 1

• Weight bearing/support
• Mineral store
• Hematopoiesis

Question 2

What is the name of the hard bone on the outside?

Answer 2

Cortical bone

Question 3

How is cortical bone organised?

Answer 3

• Osteons

- Haversian systems

Question 4

What are the two canals that exist in haversian systems?

Answer 4

• Central Haversian canal

- Horizontal volkmanns canal

Question 5

What surrounds a haversian canal?

Answer 5

• Osteocytes

- Concentric rings of bone matrix

Question 6

What is spongy bone called

Answer 6

Trabecular

Question 7

What is the structure of trabecular bone?

Answer 7

• Network of lamellated trabeculae

Question 8

Which direction do the trabeculae run?

Answer 8

In the same direction as the main mechanical force of the bone

Question 9

What is the name of the cavity inside the bone

Answer 9

Medullary cavity

Question 10

What are the 6 types of bone? (FISSSL)

Answer 10

• Flat
• Irregular
• Sesamoid
• Sutural
• Short
• Long

Question 11

What are the two types of ossification?

Answer 11

• Endochronal

- Intramembranous

Question 12

Which bones grow using endochronal ossification?

Answer 12

• Long bones

Question 13

What bones grow intramembranously?

Answer 13

• Flat bones

Question 14

Name the bones in the body that ossify intramembranously

Answer 14

• Flat bones in the skull
• Mandible
• Maxilla
• Clavicles

Question 15

Describe the stages of endochondral ossification

Answer 15

• Cartilage model forms initially
• Blood vessels invade cartilage model
• Cartilage replaced with bone
• Cartilage remains at epiphyseal growth plate for growth

Question 16

Describe the stages of intramembranous ossification

Answer 16

• No cartilaginous stage
• Mesenchymal cells mature into osteoblasts and start depositing bone
• Other mesenchymal cells become blood vessels

Question 17

What three cells are involved in bone

Answer 17

• Osteoblasts
• Osteoclasts
• Osteocytes

Question 18

What % of the extracellular matrix is hydroxyapatite?

Answer 18

45%

Question 19

What does hydroxyapatite do to bones?

Answer 19

Makes them stiff and able to support structures

Question 20

What % of the extracellular matrix is collagen?

Answer 20

35%

Question 21

What does collagen give the bone?

Answer 21

Flexibility

Question 22

What cells mediate the bones ability to remodel?

Answer 22

• Osteoclasts degrade old bone

- Osteoblasts build up new bone

Question 23

In what membranes are osteoblasts created?

Answer 23

• Periosteum

- Endosteum

Question 24

What is the osteoid?

Answer 24

Unmineralised matrix

Question 25

What bone disease can result of greater reabsorption by osteoclasts than laying down of new bone by osteoblasts?

Answer 25

Osteoporosis

Question 26

What disease results in a decrease of bone reabsorption?

Answer 26

Osteopetrosis

Question 27

Why does bone mass reduce after menopause?

Answer 27

- Oestrogen normall inhibits bone breakdown | - Less oestrogen produced