Bone structure and function Part 2

Question 1

What are the 4 types of bone cell

Answer 1

osteoblasts
osteoclasts
osteocytes
osteoprogenitor cells

Question 2

What do osteoblasts do?

Answer 2

Lays down bone matrix

Question 3

3. What do osteoclasts do?

Answer 3

resorb bone

Question 4

What do osteocytes do?

Answer 4

maintains matrix

Question 5

5. What do osteoprogenitor cells do?

Answer 5

give rise to osteoblasts involved in remodelling

Question 6

What lineage do osteoclasts come from?

Answer 6

monocyte/macrophage lineage

Question 7

Give 2 specific ways that osteoblasts perform their function

Answer 7

• Secretes organic bone matrix AKA osteoid
• Mediates mineralisation of osteoid

Question 8

what is mineralisation of osteoid?

Answer 8

deposition of inorganic salts into the osteoid

Question 9

What shape are osteoblasts?

Answer 9

Cuboidal shape

Question 10

11. Give 2 things that osteoblasts secrete

Answer 10

• collagen
• matrix vesicles

Question 11

12. what do the matrix vesicles secreted by osteoblasts contain

Answer 11

• Alkaline phosphatase and other enzymes and proteins that control the availability of calcium and phosphate

Question 12

13. What happens when the levels of calcium and phosphate levels increase to a sufficient level?

Answer 12

hydroxyapatite crystals are precipitated

Question 13

15. What are gap junctions?

Answer 13

Long cytoplasmic processes connecting to osteocytes to other osteocytes and osteoblasts

Question 14

15. What are osteocytes surrounded by?

Answer 14

surrounded by mineralised matrix

Question 15

17. Where do osteocytes sit in?

Answer 15

They sit in Lacunae

Question 16

18. How do osteocytes receive nutrients?

Answer 16

Extracellular bone fluid surrounding lacunae that allows nutrient diffusion through the bony channels

Question 17

19. What is the name of the bone channels in bone

Answer 17

canaliculi

Question 18

20. What is stress information in osteocytes?

Answer 18

when osteocytes respond to tiny currents generated when bone is deformed

Question 19

21. What do osteocytes mediate in terms of calcium?

Answer 19

Mediates short term release of calcium from bone

Question 20

22. What is a histological feature of osteoclasts?

Answer 20

They are Multinucleate

Question 21

23. What do osteoclasts attach to, what does it do and what does this leave behind?

Answer 21

attaches to bone surface, resorbing bone which leaves a pit behind

Question 22

24. What is the name for the pit left behind by osteoclasts?

Answer 22

Howships lacuna

Question 23

25. What do osteoclasts work with osteoblasts for to do?

Answer 23

Work with osteoblast to regulate bone turnover and remodelling

Question 24

25. Name 2 features of osteoclasts found on its surface

Answer 24

• Actin clear zone
• Ruffled border

Question 25

34. What does the ratio of RANKL to osteoprotegrin determine?

Answer 25

determines bone resorption

Question 26

explain bone Mineralisation

Answer 26

1. Osteoblasts secrete collagen and matrix vesicles 2. Matrix vesicles contain enzymes and proteins to control availability of calcium and phosphate 3. Needs to increase to a level where hydroxyapatite is precipitated