Bone Remodelling

Question 1

What part of the bone is in charge of longitudinal bone growth

Answer 1

Epiphyseal plate

Question 2

What are the 3 cell types in bone

Answer 2

Osteoblasts
Osteoclasts
Osteocytes

Question 3

What happens in endochrodal ossification

Answer 3

Chondrocytes die in the calcified matrix

Question 4

Function of osteoblasts

Answer 4

Build new bone

Question 5

How do osteoblasts build new bone

Answer 5

By producing and depositing osteopenia which then becomes calcified

Question 6

Function of osteoclasts

Answer 6

Breakdown bone

Question 7

How do osteoclasts break down bone

Answer 7

Secreting enzymes and acids tear dissolve bone

Question 8

What is a mature osteoblast called

Answer 8

Osteocyte

Question 9

True or false- osteocytes can revert back to osteoblasts

Answer 9

True

Question 10

Function of osteocytes

Answer 10

Monitor stress in the fluid in the cuniculi and lacuna as they help signal new bone growth

Question 11

Function of trabeculae in a normal bone

Answer 11

Allows spreading out of forces across a large surface area as it acts a shock absorber, they align along lines of stress where the force is the greatest

Question 12

Function of cortical bone in a normal bone

Answer 12

Allows spread out of forces vertically to and from spongy bone

Question 13

What are lamellae

Answer 13

Concentric rings on the osteon

Question 14

What is lacunae

Answer 14

Sites of osteocytes

Question 15

What is a Haversian canal

Answer 15

Where blood vessels travel through each osteon in canals (vertical)

Question 16

Two main cells in bone remodelling

Answer 16

Osteoblasts and osteoclasts

Question 17

Which cell is stimulated in the first remodelling stage (activation)

Answer 17

Osteocytes

Question 18

List stimulations of the activation stage

Answer 18

Stress/load/exercise
Signalling - hormone, growth factors
Injury / inflammation
Aging

Question 19

What happens to osteoclasts in the reabsorption phase

Answer 19

Begin to release acid and enzymes and starts to break down the bone

Question 20

Which of the cells complete the remodelling

Answer 20

Osteoblasts

Question 21

Which cell type is mainly involved in lengthening bone within the epiphyseal plate

Answer 21

Chondrocytes

Question 22

What happens in the proliferative zone

Answer 22

Cells are replicating

Question 23

Compare the proliferation zone and hypertrophic, what happens to cell structure

Answer 23

Cells enlarge, as chondrocytes move further away from epiphyseal edge, diffusion of nutrients is reduces and chondrocytes enlarge

Question 24

What is happening to cells in the hypertrophic zone treat explains spongy bone formation

Answer 24

Cells enlarge they begin to calcify and eventually die. Osteoblasts from metaphysical convert the calcified material into spongy

Question 25

What is wolfs law

Answer 25

Bone adapts to the load it is placed under

Question 26

Explain the arrangement in trabeculae in compressed femur

Answer 26

Tension forces push down on the head and compression forces come up the femur

Question 27

What is tension forces

Answer 27

Body weight pushing down on the head of femur

Question 28

What is compression forces

Answer 28

Impact / ground reaction forces coming up the femur during walking etc

Question 29

What is wards triangle

Answer 29

An area of weakness as there is less trabeculae

Question 30

How can wards triangle predispose rather bone to fractiure

Answer 30

It predisposes bone to fracture at the weak point especially to lateral forces which occur during a fall

Question 31

Why is the highest bone mineral density seen in high impact activities and low in low impact

Answer 31

Bone adapts to loads under it is placed, high impact actives creates high loading and this is where osteoblasts dominate and bones become stronger