Bones

Question 1

What is the function of bone?

Answer 1

Weight bearing / Support
Protection
Mineral store
Blood formation

Question 2

What are the different types of bone ?

Answer 2

Flat bone 
Sutural bone 
Short bone 
irregular bone 
Sesamoid bone 
Long bone

Question 3

What are the 5 things which make up bone ?

Answer 3

Compact and spongy bone
Blood vessels 
medullary cavity 
Bone marrow 
Membranes

Question 4

What is another name for compact bone ?

Answer 4

Cortical bone

Question 5

What is another name for spongy bone ?

Answer 5

Trabecular bone

Question 6

What are the names of the two membranes found in bone ?

Answer 6

Periosteum

Endosteum

Question 7

Where is the periosteum found ?

Answer 7

One the outsider of the bone

Question 8

Where is the endosteum found ?

Answer 8

On the inside on the bone lining the medullary cavity

Question 9

Describe the structure of compact bone

Answer 9

Compact bone has a structure called haversian system or osteons. This structure contains concentric circles (lamellae) with an haversian canal at the centre. The lamellae rings contain osteocytes which are connected by tiny channels called canaliculi.
Haversian canals are vertical cylinders containing blood vessels. Compact bone also has horizontal blood vessels containing canals called Volkmann’s channels.

Question 10

Describe the structure of spongy bone

Answer 10

Also called cancellous or trabecular bone or diploe. It is less dense than compact bone. It forms a network of lamellated trabeculae filled with bone marrow and there are no haversian systems. The orientations of the trabeculae reflects the main directional of mechanical forces.

Question 11

What kind of bone marrow fills spongy bone ?

Answer 11

Red

Question 12

What are the names of the different cells which make up bone ?

Answer 12

Osteoclasts
Osteoblasts
Osteocytes

Question 13

What is the extracellular matrix of bone made up of ?

Answer 13

Hydroxyapatite crystals
Collagen
Water

Question 14

Describe the Hydroxyapatite crystals

Answer 14

Make bone stiff and able to support other structures

High strength under compression

Question 15

Describe the collagen found in the ECM of bone

Answer 15

Some flexibility and reduces risk of fracture

High strength under tension

Question 16

What are two properties of bone which make it so amazing ?

Answer 16

• Good regenerative power - It is able to heal itself

- Good adaptive power - Able to change depending on the demands placed on it.

Question 17

What is bone turnover ?

Answer 17

The constant process which happens even in adults of bone being broken down and remade

Question 18

What cells remove bone ?

Answer 18

Osteoclasts

Question 19

What cells make new bone ?

Answer 19

Osteoblasts

Question 20

What is important about healthy bone ?

Answer 20

It will have the correct balance of bone removal and formation

Question 21

Describe the actions of osteoclasts

Answer 21

They are large multinucleated cells which are derived from haematopoietic stem cells.
They are found on the bone surface and there function it to resorb bone matrix.
They released acid to dissolve bone and create a ruffled boarder. The pit that is creaeted is called a Howships lacunae.

Question 22

Describe the actions of the osteoblasts

Answer 22

Osteoblasts are immature bone cells created from osteoprogenitor cells int he periosteum and endosteum. They produce bone matrix. They produce an osteoid the unmineralized matrix and then initiate calcification. The osteoblasts become osteocytes once’s surrounded by matrix.

Question 23

Describe the role of osteocytes

Answer 23

They are mature bone cells found in the lacunae.

They are connected by canaliculi which they use to communicate with each other.

Question 24

What are some disorders which can arise when bone remodelling goes wrong ?

Answer 24

Osteoporosis when Resorption > formation. Very problematic for spongy bone.

Pagets disease where resorption and formation are both increased. Leads to deformed bones.

Osteopetrosis where formation > resorption. Bones become like rock, dense and brittle. Can compress nerves and give rise to neurological problems.

Question 25

Describe what happens to bone mass as you age

Answer 25

It decreases especially quickly after the menopause. because oestrogen inhibits the osteoclasts, when oestrogen levels drop then more bone removal happens

Question 26

What are the names of the two types of bone formation ?

Answer 26

Endochondral

Intramembranous

Question 27

What is endochondral bone formation ?

Answer 27

Occurs inside cartilage. 
Cartilage model is made 
It is invaded by blood vessels. 
cartilage is replaced by bone (Apart from epiphyseal growth plate)
Growth plate ossifies

Question 28

What is intramembranous bone formation ?

Answer 28

Does not involve cartilage.
Mesenchymal cells develop into osteoprogenitor cells which mature into osteoblasts and start producing bone.
Mesenchymal cells develop into blood vessel and bone marrow.
occurs even in adults

Question 29

What are the two types of bone growth ?

Answer 29

Appositional growth - Outward growth

Interstitial growth - Lengthening i.e. using the growth plates

Question 30

Describe the process by which bones cells mature

Answer 30

Mesenchymal cells
osteoprogenitor cells in periosteum or endosteum
Osteoblasts
Osteocytes

Question 31

Recall points for bones

Answer 31

Functions 
Shapes
Components of bone 
Compact and spongy bone 
Extracellular matrix 
Cells 
Formation and growth