Bone: Structure and Function Flashcards Preview

**Oral Biology > Bone: Structure and Function > Flashcards

Flashcards in Bone: Structure and Function Deck (92):
1

The composition of bone is similar to _____

Dentin

2

Composition of bone is _______ overlaid on a _________ scaffold

1. Hydroxyapatite
2. Collagen I scaffold

3

What are the Non-collagenous proteins in bone?

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

4

By percentage what is the composition of bone?

67% inorganic
33% organic

5

What makes up the inorganic portion of bone?

Hydroxyapatite

6

What makes up the Organic component of bone?

28% collagen
5% noncollagenous proteins

7

Name 3 physiological roles of bone

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

8

Bone contains both ________ and _______ progenitor cell populations in marrow

1. Hematopoietic
2. Mesenchymal

9

What is the basic macrostructure of bone?

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

10

What is contained within the inner cavity of bone?

Marrow and cancellous/trabecular bone

11

What colors is marrow?

Red or yellow

12

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

True

13

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

1. Circumferential
2. Concentric/osteonic lamellae
3. Interstitial lamellae

14

What is circumferential compact bone?

Outer ring of bone tissue

15

What is Concentric/osteonic lamellae?

Intact osteons

16

What is the interstitial lamellae?

They fill the space between concentric lamellae; former concentric lamellae

17

What is the basic functional unit of compact bone?

Osteon

18

Osteons form cylinders that run in what orientation?

parallel to the long axis of a bone

19

Osteons are formed from ______

Concentric lamellae

20

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

Osteon

21

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

Haversian canals

22

What connects haversian canals and links osteons?

Volkmann canals

23

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

Cancellous bone

24

Where would you find cancellous bone?

1. At the ends of long bones, in apposition to joints
2. Associated with the marrow spaces

25

What purpose does cancellous bone serve?

Provides structural support for marrow tissues, highly vascular

26

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

Cancellous bone

27

Define the periosteum

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

28

What are the two layers of the periosteum?

1. Outer fibrous layer
2. Inner layer in apposition to the bone surface

29

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

Inner layer

30

What is the Endosteum?

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

31

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

Endosteum

32

What is the origin of Osteoblasts?

Mesenchyme

33

What would you call an encapsulated osteoblast?

Osteocyte

34

What is the origin of Osteoclasts?

Hematopoietic origin

35

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

True

36

What is the mononucleated cells that synthesize osteoid matrix?

Osteoblasts

37

In the head, what is the origin of Osteoblasts?

Ectomesenchyme

38

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

True

39

How do osteoblasts communicate with each other?

Gap junctions

*They do not form complexes

40

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

Osteoblasts

41

Osteoblasts secrete growth factors into _______

Osteoid matrix

*Then growth factors are sequestered

42

What are the growth factors secreted by Osteoblasts?

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

43

What happens to Osteoblasts after bone formation?

They flatten and form bone lining cells

44

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

Osteocytes

45

Terminal differentiation of osteoblasts forms what?

Osteocytes

46

What forms interconnected lacunae in the bone tissue?

Osteocytes

47

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

1. Mechano-transduction
2. Coordination of odontoblast/osteoclast activity

48

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

True

49

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

Osteoclast

50

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

Osteoclasts

51

What makes osteoclasts important in dentistry?

Inflammation-Activation-Resorption

52

What is the key marker for osteoclasts?

Tartrate Resistant Acid Phosphatase (TRAP)

53

What mediates the attachment of osteoclasts to bone surface?

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

54

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

True

55

Osteoclasts form resorption pits known as ___________

Howship's Lacunae

56

What do osteoclasts secrete into Howship's lacunae?

1. Hydrogen ions
2. Matrix degrading enzymes

57

What is the Lamina limitans?

The zone between the howship's lacunae and intact bone

58

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

Osteoclasts

59

What supplies new osteoblasts/osteoclasts in bone cell recruitment?

Progenitor cell populations

60

What triggers progenitor cells to differentiate?

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

61

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

True

62

Bone formation is a balance between _____ and ____ signals

1. Synthetic
2. Resorptive

63

Osteoblasts regulate osteoclast function T/F

True

64

What system is associated with Osteoblasts regulating Ostoclast function?

RANK-RANKL-OPG system

65

What does RANKL stand for?

Receptor Activated Nuclear factor kB Ligand

*Associated with Osteoblasts

66

What does RANK stand for?

Receptor Activated Nuclear Factor kB

*Associated with Osteoclasts

67

What does OPG stand for and what does it do?

Osteoprotegerin

*Produced by osteoblasts and binds RANKL

68

How do long bones form?

Endochondral ossification

69

How do bones of the skull form?

Intramembranous ossification

70

T/F Endochondral and intramemranous ossification are exclusive processes

False

71

What is sutural bone growth?

Fusion of skull plates

72

T/F Vascular supply is very important in ossification

True

73

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

Endochondral Formation

74

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

Endochondral

75

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

1. Collagen
2. Chondroclasts
3. Penetration of vasculature

76

What does the vasculature bring with it ?

Mesenchymal cells which differentiate into osteoblasts

77

What makes up primary spongiosa?

Bone matrix surrounds remaining mineralized collagen forming mixed spicules

78

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

Osteoclasts

79

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

Secondary growth centers

80

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

1. Mesenchymal cells
2. Osteoblasts

81

In intramembranous formation, After mesenchymal cells condense what happens?

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

*Leads to rapid formation of mineralized 'woven bone'

82

In Intramembranous formation, what happens to the woven bone?

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

83

Sutures are ______ connective tissue bands between plates

Fibrous

*They allow for internal expansion of organs

84

What are the 2 layers in sutural bone growth?

1. Inner cambian layer associated with periosteum
2. Outer capsular layers meet to join sutures together

85

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

Sutural bone growth

86

What is the rate of bone turnover in children?

30-100% of their total bone per year

87

What is the rate of bone turnover in adults?

5% cortical and 15% trabecular per year

88

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

1. Periosteum
2. Endosteum

89

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

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

90

What factors control bone remodeling and repair process?

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

91

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

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

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

True

*Gradual replacement allows for this