Bone

Question 1

What are some of the functions of bone?

Answer 1

Weight bearing/support

Protection

Mineral store

Blood formation

Question 2

What is the gross anatomy of a bone composed of?

Answer 2

Compact bone

Spongy bone

Blood vessels

Medullary cavity

Bone marrow

Membranes (periosteum/endosteum)

Question 3

What are the circular structures that compact bone is organised into?

Answer 3

Osteons/Haversian systems

Question 4

What are the osteons/Haversian canals composed of?

Answer 4

Central Haversian canal and horizontal perforating/Volkmann’s canals where blood vessels are

Question 5

What is found in Volkmann’s canals?

Answer 5

Blood vessels

Question 6

What is found in the Haversian canal?

Answer 6

Osteocytes and concentric rings of bone marrow

Question 7

What is an osterocyte?

Answer 7

A bone cell

Question 8

What is more dense out of spongy and compact bone?

Answer 8

Spongy bone

Question 9

What network is found in spongy bone?

Answer 9

Network of lamellated trabeculae filled with bone marrow

Question 10

What is the lamellated trabeculae filled with?

Answer 10

Bone marrow

Question 11

Are Haversian systems found in spongy bone?

Answer 11

No

Question 12

What does the orientation of trabeculae reflect?

Answer 12

Direction of the mechnical force

Question 13

What are some different types of bones?

Answer 13

Flat bone (frontal)

Sutural bone

Short bone (carpal)

Irregular bone (vertebra)

Sesamoid bone (patella)

Long bone (femur)

Question 14

What are the 2 types of bone formation?

Answer 14

Endochrondral

Intramembraneous

Question 15

What is the process of endochondrial ossification?

Answer 15

1. Bone forms as cartilage model
2. Blood vessels invase cartilage
3. Cartilage replaced with bone
4. Cartilage reamins in epiphyseal growth plate, which eventually ossifies

Question 16

What is ossification?

Answer 16

Process of laying down new bone material by cells called osteoblasts

Question 17

What is the process of intramembraneous ossification?

Answer 17

1. Mesenchymal cells develop into osteoprogenitor cells that mature into osteoblasts that start developing bone
2. Residual mesenchymal cells develop blood vessels and bone marrow

Question 18

What are the 3 cells that make up bone?

Answer 18

Osteoblasts

Osteocyte

Osteoclasts

Question 19

What do osteoblasts do?

Answer 19

Form new bone

Question 20

What do osteoclasts do?

Answer 20

Destroys old bone

Question 21

What is the extracellular matrix composed of?

Answer 21

45% hydroxyapatite crystals (complex form of calcium phosphate)

35% collagen (type I)

20% water

Question 22

What do minerals do to bones?

Answer 22

Make them stiff and give them strength

Question 23

What does collagen do to bones?

Answer 23

Gives them flexibility, increasing strength under tension

Question 24

Why is bone dynamic?

Answer 24

Due to bone turnover, new bone is constantly being formed

Question 25

What is the process of new bone constantly being formed?

Answer 25

1. Osteoclasts break down old bone 2. Osteoblasts build new bone

Question 26

Are osteoblasts immature or mature?

Answer 26

Immature

Question 27

What are osteoblasts derived from?

Answer 27

Osteopreginitor cells

Question 28

What is a function of osteoblasts?

Answer 28

Produce the bone matrix

Question 29

What do osteoblasts do when they are surrounding by matrix?

Answer 29

Become osteocytes

Question 30

Are osteocytes mature or immature?

Answer 30

Mature

Question 31

Where are osteocytes found?

Answer 31

Inside lacunae

Question 32

What are osteocytes connected to each other by?

Answer 32

Canaliculi

Question 33

What does canalucili allow?

Answer 33

Osteocytes to communicate with each other

Question 34

What are functions of osteocytes?

Answer 34

Maintain the bone matrix Sense mechanical force

Question 35

What are osteoclasts derived from?

Answer 35

Haematopoietic stem cells

Question 36

Where are osteoclasts found?

Answer 36

On bone surfaces

Question 37

What is the function of osteoclasts?

Answer 37

Resorb bone matrix

Question 38

What is the resorption pit of an osteroclast called?

Answer 38

Howship's lacunae

Question 39

When does bone disease occur?

Answer 39

When remodelling is not balanced

Question 40

What are some examples of bone diseases?

Answer 40

Osteoporosis (resorption \> formation) Paget's disease (resorption and formation greater) Osteopetrosis (low resorption)

Question 41

What is bone mass controlled by?

Answer 41

Genes and the environment

Question 42

What happens to bone mass as you get older?

Answer 42

It decreases

Question 43

How does mechnical load regulate bone mass?

Answer 43

You loss what you don't use