Bone: Structure and Function Flashcards

1
Q

The composition of bone is similar to _____

A

Dentin

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2
Q

Composition of bone is _______ overlaid on a _________ scaffold

A
  1. Hydroxyapatite

2. Collagen I scaffold

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3
Q

What are the Non-collagenous proteins in bone?

A
  1. BSP
  2. OP
  3. OC
  4. ON
  5. Matrix Extracellular Phosphoglycoprotein
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4
Q

By percentage what is the composition of bone?

A

67% inorganic

33% organic

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5
Q

What makes up the inorganic portion of bone?

A

Hydroxyapatite

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6
Q

What makes up the Organic component of bone?

A

28% collagen

5% noncollagenous proteins

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7
Q

Name 3 physiological roles of bone

A
  1. Structural
  2. Calcium Homeostasis (9-10mg/DL)
  3. Reservoir for growth factors in tissue repair
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8
Q

Bone contains both ________ and _______ progenitor cell populations in marrow

A
  1. Hematopoietic

2. Mesenchymal

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9
Q

What is the basic macrostructure of bone?

A

Outer layer of dense compact/cortical bone with an inner cavity

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10
Q

What is contained within the inner cavity of bone?

A

Marrow and cancellous/trabecular bone

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11
Q

What colors is marrow?

A

Red or yellow

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12
Q

T/F Bone is highly vascular with a network of blood vessels

A

True

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13
Q

What are the 3 organizational units in the macrostructure of compact bone?

A
  1. Circumferential
  2. Concentric/osteonic lamellae
  3. Interstitial lamellae
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14
Q

What is circumferential compact bone?

A

Outer ring of bone tissue

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15
Q

What is Concentric/osteonic lamellae?

A

Intact osteons

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16
Q

What is the interstitial lamellae?

A

They fill the space between concentric lamellae; former concentric lamellae

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17
Q

What is the basic functional unit of compact bone?

A

Osteon

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18
Q

Osteons form cylinders that run in what orientation?

A

parallel to the long axis of a bone

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19
Q

Osteons are formed from ______

A

Concentric lamellae

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20
Q

What would you call a concentric ring of bone, built around a canal housing a capillary?

A

Osteon

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21
Q

What would we call the canal that runs in the osteon?

A

Haversian canals

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22
Q

What connects haversian canals and links osteons?

A

Volkmann canals

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23
Q

What do we call the spongy bone that is much less densely arranged than compact bone?

A

Cancellous bone

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24
Q

Where would you find cancellous bone?

A
  1. At the ends of long bones, in apposition to joints

2. Associated with the marrow spaces

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25
Q

What purpose does cancellous bone serve?

A

Provides structural support for marrow tissues, highly vascular

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26
Q

What type of bone is a site of blood cell production and supports mesenchymal and hematopoietic progenitor cell populations?

A

Cancellous bone

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27
Q

Define the periosteum

A

Connective Tissue layer attached to the outer surface of a bone by Sharpey’s fibers

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28
Q

What are the two layers of the periosteum?

A
  1. Outer fibrous layer

2. Inner layer in apposition to the bone surface

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29
Q

Which layer of the periosteum is both highl cellular and vascularized?

A

Inner layer

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30
Q

What is the Endosteum?

A

Loose Connective tissue covering the inner surface of both cancellous and compact bone

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31
Q

What separates the marrow from the bone and is poorly defined histologically?

A

Endosteum

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32
Q

What is the origin of Osteoblasts?

A

Mesenchyme

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33
Q

What would you call an encapsulated osteoblast?

A

Osteocyte

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34
Q

What is the origin of Osteoclasts?

A

Hematopoietic origin

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35
Q

Carefully regulated interaction between Osteoblasts, Osteocytes, and Osteoclasts is responsible for bone formation, repair, and maintenance T/F

A

True

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36
Q

What is the mononucleated cells that synthesize osteoid matrix?

A

Osteoblasts

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37
Q

In the head, what is the origin of Osteoblasts?

A

Ectomesenchyme

38
Q

T/F Osteoblasts have a role in both bone formation and repair

A

True

39
Q

How do osteoblasts communicate with each other?

A

Gap junctions

*They do not form complexes

40
Q

What bone cells produce and secrete collagen and non collagenous proteins via vesicles?

A

Osteoblasts

41
Q

Osteoblasts secrete growth factors into _______

A

Osteoid matrix

*Then growth factors are sequestered

42
Q

What are the growth factors secreted by Osteoblasts?

A
  1. TGFB1
  2. BMP-2
  3. IGF I & II
  4. PDGF
  5. FGF
43
Q

What happens to Osteoblasts after bone formation?

A

They flatten and form bone lining cells

44
Q

What do you call osteoblasts which embed themselves into bone matrix?

A

Osteocytes

45
Q

Terminal differentiation of osteoblasts forms what?

A

Osteocytes

46
Q

What forms interconnected lacunae in the bone tissue?

A

Osteocytes

47
Q

Osteocytes have cellular processes which interact with surrounding bone tissue. What purpose do these processes serve?

A
  1. Mechano-transduction

2. Coordination of odontoblast/osteoclast activity

48
Q

T/F Osteocytes possible work in conjunction with bone lining cells

A

True

49
Q

What would you call a large multi-nucleated bone cell that is a fusion of monocytes?

A

Osteoclast

50
Q

Which bone cell is activated in inflammation (IL-1B, TNF-a)

A

Osteoclasts

51
Q

What makes osteoclasts important in dentistry?

A

Inflammation-Activation-Resorption

52
Q

What is the key marker for osteoclasts?

A

Tartrate Resistant Acid Phosphatase (TRAP)

53
Q

What mediates the attachment of osteoclasts to bone surface?

A
  1. Integrin
  2. Cytoplasm adjacent to surface rich in Talin
  3. Actin
  4. Vinculin
54
Q

T/F In opposition to bone, Osteoclasts form a ruffled border

A

True

55
Q

Osteoclasts form resorption pits known as ___________

A

Howship’s Lacunae

56
Q

What do osteoclasts secrete into Howship’s lacunae?

A
  1. Hydrogen ions

2. Matrix degrading enzymes

57
Q

What is the Lamina limitans?

A

The zone between the howship’s lacunae and intact bone

58
Q

Trancytosis of matrix components would be associated with which bone cell?

A

Osteoclasts

59
Q

What supplies new osteoblasts/osteoclasts in bone cell recruitment?

A

Progenitor cell populations

60
Q

What triggers progenitor cells to differentiate?

A
  1. Signaling cascades
  2. Tissue damage
  3. Inflammation
  4. Repair signals
61
Q

T/F Bone formation is controlled by the complex interactions between osteoblasts and osteoclasts

A

True

62
Q

Bone formation is a balance between _____ and ____ signals

A
  1. Synthetic

2. Resorptive

63
Q

Osteoblasts regulate osteoclast function T/F

A

True

64
Q

What system is associated with Osteoblasts regulating Ostoclast function?

A

RANK-RANKL-OPG system

65
Q

What does RANKL stand for?

A

Receptor Activated Nuclear factor kB Ligand

*Associated with Osteoblasts

66
Q

What does RANK stand for?

A

Receptor Activated Nuclear Factor kB

*Associated with Osteoclasts

67
Q

What does OPG stand for and what does it do?

A

Osteoprotegerin

*Produced by osteoblasts and binds RANKL

68
Q

How do long bones form?

A

Endochondral ossification

69
Q

How do bones of the skull form?

A

Intramembranous ossification

70
Q

T/F Endochondral and intramemranous ossification are exclusive processes

A

False

71
Q

What is sutural bone growth?

A

Fusion of skull plates

72
Q

T/F Vascular supply is very important in ossification

A

True

73
Q

What type of formation is bone formed formed on a hyaline cartilage pattern?

A

Endochondral Formation

74
Q

Condensation of mesenchymal cells into chondrocytes happens in what type of bone formation?

A

Endochondral

75
Q

In endochondral ossification ____ is secreted, minerlizes and is broken down by _______, which allows what?

A
  1. Collagen
  2. Chondroclasts
  3. Penetration of vasculature
76
Q

What does the vasculature bring with it ?

A

Mesenchymal cells which differentiate into osteoblasts

77
Q

What makes up primary spongiosa?

A

Bone matrix surrounds remaining mineralized collagen forming mixed spicules

78
Q

In endochondrdal ossification, what gradually removes mineralized cartilage and develop marrow cavity?

A

Osteoclasts

79
Q

In endochondral ossification ______ form in the epiphyses of some long bones

A

Secondary growth centers

80
Q

In intramembranous formation, ______ condense in fibrous connective tissue, differentiating into ________ and forming an ossification center

A
  1. Mesenchymal cells

2. Osteoblasts

81
Q

In intramembranous formation, After mesenchymal cells condense what happens?

A

Osteoid is secreted into the connective tissue matrix and is penetrated by blood vessels

*Leads to rapid formation of mineralized ‘woven bone’

82
Q

In Intramembranous formation, what happens to the woven bone?

A

Woven bone remodeled into mature trabecular bone with a collar of cortical bone around it

83
Q

Sutures are ______ connective tissue bands between plates

A

Fibrous

*They allow for internal expansion of organs

84
Q

What are the 2 layers in sutural bone growth?

A
  1. Inner cambian layer associated with periosteum

2. Outer capsular layers meet to join sutures together

85
Q

What type of bone growth allows flex to the skull as bone formation proceeds?

A

Sutural bone growth

86
Q

What is the rate of bone turnover in children?

A

30-100% of their total bone per year

87
Q

What is the rate of bone turnover in adults?

A

5% cortical and 15% trabecular per year

88
Q

Most bone formation happens around the _____, while most bone resorption happens from the _______

A
  1. Periosteum

2. Endosteum

89
Q

Generally speaking, what does Bone remodeling and repair look like in cortical bone?

A

Primary osteons replaced by secondary osteons, which are replaced by tertiary osteons, allowing bone growth

90
Q

What factors control bone remodeling and repair process?

A

Cascade of factors both cellular, systemic, and sequestered growth factors in bone matrix

91
Q

What is the cutting cone vs. filling cone model of bone remodeling/repair

A
  1. Osteoclasts resorb bone, leaving a space which is filled by trailing osteoblasts
  2. Osteoblasts create a cement (non collagenous proteins) and lay new bone onto it
92
Q

T/F Bone needs to be structurally function and growing at the same time

A

True

*Gradual replacement allows for this