Bone

Question 1

what cells are found in bone?

Answer 1

• osteoprogenitor cells
• osteoblasts
• osteocytes
• osteoclasts

Question 2

what are osteoprogenitor cells?

Answer 2

stem cell population

Question 3

what is in the extracellular matrix of bone?

Answer 3

• collagen

- calcium hydroxyapatite

Question 4

what do osteoprogenitor cells differentiate into?

Answer 4

osteoblasts

Question 5

what is the appearance of osteoprogenitor cells?

Answer 5

flat, spindle shaped cells

closely applied to bone surface

Question 6

what do osteoblasts originate from?

Answer 6

embryonic mesenchyme (osteoprogenitor cells)

Question 7

what do osteoblasts secrete?

Answer 7

osteoid

Question 8

what is osteoid?

Answer 8

unmineralised bone

Question 9

where are osteoblasts found?

Answer 9

surface of bone

Question 10

where are osteocytes found?

Answer 10

extracellular matrix

Question 11

how to osteocytes connect to surrounding cells?

Answer 11

via canaliculi

Question 12

how do osteocytes stay alive?

Answer 12

Oxygen and nutrients diffuse through canaliculi

Question 13

what do osteoclasts originate from?

Answer 13

monocytes

Question 14

what is the structure of osteoclasts?

Answer 14

mononucleate

Question 15

where are osteoclasts found?

Answer 15

bone surface

Question 16

what are Howship’s Lacunae?

Answer 16

depressions in the bone made by osteoclasts when they absorb it

Question 17

how is the activity of osteoblasts and osteoclasts coordinated?

Answer 17

by a number of chemical messengers, e.g. RANK-Ligand

Question 18

when does bone remodelling occur?

Answer 18

throughout life

Question 19

what are the types of bone based on the pattern of collagen fibres within it?

Answer 19

• primary (woven)

- secondary (lamellar)

Question 20

what are the types of ossification?

Answer 20

• membranous

- endochondral

Question 21

what are the types of bone based on naked eye appearance?

Answer 21

• spongy/cancellous

- compact

Question 22

what is another way of dividing bone types?

Answer 22

• osteons

- appositional

Question 23

where is primary bone laid down?

Answer 23

• foetal bones

- fracture sites

Question 24

what is the structure of primary bone?

Answer 24

• disorganised collagen fibre architecture

- mechanically weak

Question 25

is primary or secondary bone stronger?

Answer 25

secondary

Question 26

what is secondary bone formed as?

Answer 26

osteons

Question 27

what are osteons?

Answer 27

- central Haversian canal containing a blood vessel | - surrounding concentric rings of lamellar bone with osteocytes

Question 28

describe the composition of osteoid

Answer 28

- type I collage - glycosaminoglycans - proteoglycans

Question 29

describe the composition of glycosaminoglycans

Answer 29

Includes compounds such as osteocalcin - strong affinity for Ca2+

Question 30

what bone is formed from deposition of parallel sheets?

Answer 30

lamellar

Question 31

what bone is formed from deposition of haphazard bone?

Answer 31

woven

Question 32

what stimulates osteoid mineralisation?

Answer 32

high local concentration of calcium & phosphate ions

Question 33

what aids the mineralisation of osteoid?

Answer 33

osteocalcin | - binds Ca2+ and alkaline phosphatase

Question 34

what is calcium deposited in bone as?

Answer 34

calcium hydoxyapatite

Question 35

what type of bone does intramembranous ossification form?

Answer 35

* flat skull bones | * some cortical bone shafts

Question 36

what is intramembranous ossification?

Answer 36

Formation of bone from a membranous precursor

Question 37

when does intramembranous ossification begin?

Answer 37

2nd trimester of embryonic life

Question 38

which type of ossification uses a cartilaginous pro forma?

Answer 38

endochondral

Question 39

what is endochondral ossification?

Answer 39

Converts hyaline cartilaginous template into bone

Question 40

what is the synovium?

Answer 40

Specialised tissue that lines the inside of the synovial joint capsule

Question 41

what are synovial joints lined by?

Answer 41

hyaline cartilage on the articular surface

Question 42

what are the types of synovial cell?

Answer 42

- type A | - type B

Question 43

what are type A synovial cells?

Answer 43

phagocytes

Question 44

what are type B synovial cells?

Answer 44

* rich in rER | * secrete synovial fluid

Question 45

how many layers of synovial cells does synovium have?

Answer 45

1-4

Question 46

describe the structure of synovium

Answer 46

- variable shapes - squamous to cuboidal - richly vascular - highly innervated