Bone: Structure and Function Flashcards
1
Q
The composition of bone is similar to _____
A
Dentin
2
Q
Composition of bone is _______ overlaid on a _________ scaffold
A
- Hydroxyapatite
2. Collagen I scaffold
3
Q
What are the Non-collagenous proteins in bone?
A
- BSP
- OP
- OC
- ON
- Matrix Extracellular Phosphoglycoprotein
4
Q
By percentage what is the composition of bone?
A
67% inorganic
33% organic
5
Q
What makes up the inorganic portion of bone?
A
Hydroxyapatite
6
Q
What makes up the Organic component of bone?
A
28% collagen
5% noncollagenous proteins
7
Q
Name 3 physiological roles of bone
A
- Structural
- Calcium Homeostasis (9-10mg/DL)
- Reservoir for growth factors in tissue repair
8
Q
Bone contains both ________ and _______ progenitor cell populations in marrow
A
- Hematopoietic
2. Mesenchymal
9
Q
What is the basic macrostructure of bone?
A
Outer layer of dense compact/cortical bone with an inner cavity
10
Q
What is contained within the inner cavity of bone?
A
Marrow and cancellous/trabecular bone
11
Q
What colors is marrow?
A
Red or yellow
12
Q
T/F Bone is highly vascular with a network of blood vessels
A
True
13
Q
What are the 3 organizational units in the macrostructure of compact bone?
A
- Circumferential
- Concentric/osteonic lamellae
- Interstitial lamellae
14
Q
What is circumferential compact bone?
A
Outer ring of bone tissue
15
Q
What is Concentric/osteonic lamellae?
A
Intact osteons
16
Q
What is the interstitial lamellae?
A
They fill the space between concentric lamellae; former concentric lamellae
17
Q
What is the basic functional unit of compact bone?
A
Osteon
18
Q
Osteons form cylinders that run in what orientation?
A
parallel to the long axis of a bone
19
Q
Osteons are formed from ______
A
Concentric lamellae
20
Q
What would you call a concentric ring of bone, built around a canal housing a capillary?
A
Osteon
21
Q
What would we call the canal that runs in the osteon?
A
Haversian canals
22
Q
What connects haversian canals and links osteons?
A
Volkmann canals
23
Q
What do we call the spongy bone that is much less densely arranged than compact bone?
A
Cancellous bone
24
Q
Where would you find cancellous bone?
A
- 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
