Microstructure of bone

Question 1

What is the main type of collagen in bone

Answer 1

Type 1

Question 2

What forms the osteoid

Answer 2

Non- collagenous proteins and ground substances (glycoproteins and proteoglycans)

Question 3

Formula of hydroxyapatite

Answer 3

Ca10(PO4)6OH2

Question 4

When does the notochord develops

Answer 4

3rd week after conception

Question 5

When are the first signs of arms and legs

Answer 5

4th week after conception

Question 6

When do the first bone cells appear

Answer 6

8th week after conception

Question 7

Function of bone

Answer 7

Protection
Support - produce max strength with min material and to resist max compressional stress
Movement 
Reservoir - for essential minerals 
Blood cell formation

Question 8

Cortical bone

Answer 8

80% skeletal mass
Compact or lamellar bone
Mature form of bone
Bundles of collagen fibres in the bone matrix are organised into successive sheets and in same direction

Question 9

Is cortical bone remodelled from woven bone

Answer 9

Yes

Woven bone is also known as immature bone

Question 10

What is the primary structure of the cortical bone

Answer 10

Osteon

Also known as Haversian system

Question 11

What is the outside bone

Answer 11

Cortical bone - solid bone

Question 12

What is the inside bone

Answer 12

Trabecular bone - spongy, elastic bone

Question 13

Trabecular bone

Answer 13

20% skeletal mass
Less dense, elastic, higher turnover rate than cortical bone
Contributes most of the bone tissue of the axial skeleton

Question 14

Where is woven bone formed

Answer 14

During embryonic development, fracture healing and in some pathological sites
Randomly arranged collagen bundles
Normally remodelled in cortical or cancellous bone except in a few places where woven bone persists - where tendons insert into bones and the tooth sockets

Question 15

What is external bone covered by

Answer 15

Periosteum - covers and protects the outer surface of bones that are not covered by cartilage

Question 16

Double membrane of periosteum

Answer 16

Outer fibrous layer - dense irregular connective tissue. protective layer
Inner layer - Delicate osteogenic layer, contains mainly osteoblasts and osteoclasts

Question 17

What are osteoblasts and osteoclasts

Answer 17

Osteoblasts = bone forming cells 
Osteoclasts = bone destroying cells

Question 18

How is periosteum anchored to bone

Answer 18

Sharpeys fibres (strands of collagen fibres)

Question 19

What is internal bone covered by

Answer 19

Endosteum

Osteogenic membrane - delicate connective membrane containing mainly osteocytes and osteoclasts

Question 20

What are the two types of ossification

Answer 20

Intramembranous - replacement of thin c.t membrane with bone - flat bones
Endochondral - replacement of fetal cartilage skeleton with bone - long, irregular and short bone

Question 21

Osteoblasts, clasts and cytes

Answer 21

Osteoblasts - form the collagen, glycoproteins and proteoglycans of the matrix, control the deposition of mineral crystals on the fibrils (MAKE)
Osteocytes - Maintaining the matrix of its territory. (MAINTAIN)
Osteoclasts - Very lage, multi nucleated, bone resorbing cells (RESORB/ DESTROY)

Question 22

Mineral contents

Answer 22

Alveolar bone - 70% (inorganic)
Cementum - 70% (inorganic)
Dentine - 70% (inorganic) 
Enamel - 96% (inorganic)
Pulp - none

Question 23

What is bone homeostasis

Answer 23

Bone resorption and formation are balanced allowing for continual renewal of skeletal tissue and repair of micro damage