Bone Flashcards

1
Q

what cells are found in bone?

A
  • osteoprogenitor cells
  • osteoblasts
  • osteocytes
  • osteoclasts
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2
Q

what are osteoprogenitor cells?

A

stem cell population

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3
Q

what is in the extracellular matrix of bone?

A
  • collagen

- calcium hydroxyapatite

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4
Q

what do osteoprogenitor cells differentiate into?

A

osteoblasts

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5
Q

what is the appearance of osteoprogenitor cells?

A

flat, spindle shaped cells

closely applied to bone surface

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6
Q

what do osteoblasts originate from?

A

embryonic mesenchyme (osteoprogenitor cells)

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7
Q

what do osteoblasts secrete?

A

osteoid

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8
Q

what is osteoid?

A

unmineralised bone

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9
Q

where are osteoblasts found?

A

surface of bone

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10
Q

where are osteocytes found?

A

extracellular matrix

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11
Q

how to osteocytes connect to surrounding cells?

A

via canaliculi

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12
Q

how do osteocytes stay alive?

A

Oxygen and nutrients diffuse through canaliculi

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13
Q

what do osteoclasts originate from?

A

monocytes

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14
Q

what is the structure of osteoclasts?

A

mononucleate

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15
Q

where are osteoclasts found?

A

bone surface

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16
Q

what are Howship’s Lacunae?

A

depressions in the bone made by osteoclasts when they absorb it

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17
Q

how is the activity of osteoblasts and osteoclasts coordinated?

A

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

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18
Q

when does bone remodelling occur?

A

throughout life

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19
Q

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

A
  • primary (woven)

- secondary (lamellar)

20
Q

what are the types of ossification?

A
  • membranous

- endochondral

21
Q

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

A
  • spongy/cancellous

- compact

22
Q

what is another way of dividing bone types?

A
  • osteons

- appositional

23
Q

where is primary bone laid down?

A
  • foetal bones

- fracture sites

24
Q

what is the structure of primary bone?

A
  • disorganised collagen fibre architecture

- mechanically weak

25
Q

is primary or secondary bone stronger?

A

secondary

26
Q

what is secondary bone formed as?

A

osteons

27
Q

what are osteons?

A
  • central Haversian canal containing a blood vessel

- surrounding concentric rings of lamellar bone with osteocytes

28
Q

describe the composition of osteoid

A
  • type I collage
  • glycosaminoglycans
  • proteoglycans
29
Q

describe the composition of glycosaminoglycans

A

Includes compounds such as osteocalcin

  • strong affinity for Ca2+
30
Q

what bone is formed from deposition of parallel sheets?

A

lamellar

31
Q

what bone is formed from deposition of haphazard bone?

A

woven

32
Q

what stimulates osteoid mineralisation?

A

high local concentration of calcium & phosphate ions

33
Q

what aids the mineralisation of osteoid?

A

osteocalcin

- binds Ca2+ and alkaline phosphatase

34
Q

what is calcium deposited in bone as?

A

calcium hydoxyapatite

35
Q

what type of bone does intramembranous ossification form?

A
  • flat skull bones

* some cortical bone shafts

36
Q

what is intramembranous ossification?

A

Formation of bone from a membranous precursor

37
Q

when does intramembranous ossification begin?

A

2nd trimester of embryonic life

38
Q

which type of ossification uses a cartilaginous pro forma?

A

endochondral

39
Q

what is endochondral ossification?

A

Converts hyaline cartilaginous template into bone

40
Q

what is the synovium?

A

Specialised tissue that lines the inside of the synovial joint capsule

41
Q

what are synovial joints lined by?

A

hyaline cartilage on the articular surface

42
Q

what are the types of synovial cell?

A
  • type A

- type B

43
Q

what are type A synovial cells?

A

phagocytes

44
Q

what are type B synovial cells?

A
  • rich in rER

* secrete synovial fluid

45
Q

how many layers of synovial cells does synovium have?

A

1-4

46
Q

describe the structure of synovium

A
  • variable shapes
    • squamous to cuboidal
  • richly vascular
  • highly innervated