QUIZ 4 Bone: Structure and Function Flashcards
1
Q
bone is composed as ___ overlaid on a ___ scaffold
A
- hydroxyapatite
- collagen I
2
Q
what are the non-collagenous proteins found in bone?
A
- bone sialoprotein (BSP)
- osteopontin (OP)
- osteocalcin (OC)
- osteonectin (ON)
- matrix extracellular phosphoglycoprotein
3
Q
bone is ___% inorganic and ___% organic
A
- 67
- 33
4
Q
describe the organic component of bone
A
- 33% of overall bone composition
- 28% collagen, 5% noncollagenous proteins
5
Q
what are the physiological roles of bone?
A
- structural
- calcium homeostasis (9-10 mg/dL)
- reservoir for growth factors in tissue repair
- contains both hematopoietic and mesenchymal progenitor cell populations in marrow
6
Q
describe the macrostructure of bone
A
- outer layer of dense compact (cortical) bone, with an inner cavity
- inner cavity contains marrow (red or yellow) and cancellous (trabecular) bone
- bone is highly vascular with a network of blood vessels
7
Q
describe the macrostructure of compact bone
A
- 3 organizational units
- circumferential - outer ring of bone tissue
- concentric (osteonic) lamellae - intact osteons
- interstitial lamellae - fill space between concentric lamellae; former concentric lamellae
8
Q
the ___ is the basic functional unit of compact bone
A
osteon
9
Q
___ connect haversian canals, linking osteons
A
volkmann’s canals
10
Q
describe osteons
A
- form cylinders running parallel to the long axis of a bone
- formed from concentric lamellae
- concentric rings of bone, built around a canal housing a capillary (haversian canal)
11
Q
___ is found at the ends of long bones, in apposition to joints and is associated with the marrow spaces
A
cancellous bone
12
Q
what is the function of cancellous bone?
A
provides structural support for marrow tissues, and is highly vascular
13
Q
cancellous bone is the site of ___ production, and also supports ___ and ___ progenitor cell populations
A
- blood cell
- mesenchymal and hematopoietic
14
Q
what is the periosteum?
A
- connective tissue layer attached to the outer surface of a bone by sharpey’s fibers
- consists of two layers - outer fibrous layer and inner layer in apposition to the bone surface
- the inner layer is both highly cellular and highly vascularized
15
Q
what is the endosteum?
A
- loose connective tissue covering the inner surface of both cancellous and compact bone
- separate the marrow from the bone
- poorly defined histologically
16
Q
what are the 3 bone cells, and what are their functions?
A
- osteoblasts - bone forming cells with a mesenchymal origin
- osteocytes - bone cells; encapsulated osteoblasts (also mesenchymal in origin)
- osteoclasts - cells that break down bone tissue; hematopoietic origin
17
Q
the carefully regulated interactions between osteoblasts, osteocytes, and osteoclasts is responsible for ___, ___, and ___
A
bone formation, repair, and maintenance
18
Q
___ are mononucleated cells which synthesize osteoid matrix
A
osteoblasts
19
Q
osteoblasts arise from ___
A
mesenchyme (ectomesenchyme in the head)
20
Q
osteoblasts differentiate in response to a cascade of ___
A
growth factors
21
Q
osteoblasts have a role in both ___ and ___
A
bone formation and repair
22
Q
osteoblasts communicate with each other through ___
A
gap junctions
they do not form complexes
23
Q
what do osteoblasts produce? what do they secrete?
A
- produce osteoid matrix, similar to odontoblasts
- produce AND secrete collagen, non collagenous proteins via vesicles
- secrete growth factors into osteoid matrix, where they are sequestered (TGF-beta-1, BMP2, IGF I and II, PDGF, FGF)
24
Q
after bone formation, ___ flatten and form bone lining cells
A
osteoblasts
25
\_\_\_ are osteoblasts that embed themselves into bone matrix
osteocytes
26
the terminal differentiation for osteoblasts in what cell?
osteocytes
27
osteocytes form ___ in bone tissue
interconnected lacunae
28
osteocytes have cellular processes which interact with surrounding bone tissue. describe this.
* mechano-transduction
* coordination of odontoblast/osteoclast activity
* mechanical forces → osteocyte stimulates osteoblast and osteoclast activity
29
\_\_\_ are large multi-nucleated cells that are a fusion of monocytes
osteoclasts
30
\_\_\_ are responsible for the resorption of bone
osteoclasts
31
osteoclasts are activated in inflammation by ___ and \_\_\_
IL-1beta and TNF-alpha
32
why are osteoclasts important in dentistry?
inflammation → activation → resorption
33
what is the key marker of osteoclasts?
tartrate resistant acid phosphatase (TRAP)
34
the attachment of osteoclasts to surface is mediated by what?
integrin, cytoplasm adjacent to surface rich in talin, actin, and vinculin
35
\_\_\_ form a ruffled border in apposition to bone
osteoclasts
36
osteoclasts form \_\_\_, and secrete ___ and \_\_\_
* resorption pits (howship's lacunae)
* hydrogen ions and matrix degrading enzymes
37
\_\_\_ is the zone between the howship's lacunae and intact bone
lamina limitans
38
describe bone cell recruitment
* osteoblast/osteoclasts supplied by progenitor cell populations
* differentiate in response to signaling cascade(s)
* also triggered by tissue damage, inflammation, repair signals
39
bone formation is controlled by what?
the complex interactions between osteoblasts and osteoclasts
40
bone formation is controlled via a balance between ___ and ___ signals
synthetic and resorptive
41
in the control of bone formation, osteoblasts regulate osteoclast function via the ___ system
RANK-RANKL-OPG
42
\_\_\_ is very important in ossification
vascular supply
43
how are long bones formed?
endochondral bone formation
44
how are bones of the skull formed?
intramembranous ossification
45
what is an example of sutural bone growth?
fusion of skull plates
46
endochondral ossification is bone formed on a ___ cartilage pattern
hyaline
47
endochondral ossification involves the condensation of ___ cells into \_\_\_
* mesenchymal
* chondrocytes
48
during endochondral ossification, ___ is secreted, which then mineralizes and is broken down by \_\_\_, allowing penetration of vasculature. with vasculature comes mesenchymal cells which differentiate into \_\_\_. ___ surrounds remaining mineralized collagen, forming mixed spicules which make up \_\_\_. ___ gradually remove mineralized cartilage and develop marrow cavity.
* collagen
* chondroclasts
* osteoblasts
* bone matrix
* primary spongiosa
* osteoclasts
49
\_\_\_ form in the epiphyses of some long bones (growth plates)
secondary growth centers
50
in intramembranous formation, ___ condense in fibrous connective tissue, differentiating into osteoblasts and forming an \_\_\_. ___ is secreted into the connective tissue matrix and is penetrated by blood vessels. rapid formation of mineralized ___ bone. ___ bone is remodeled into mature ___ bone with a collar of ___ bone around it.
* mesenchymal cells
* ossification center
* osteoid
* woven
* woven
* trabecular
* cortical
51
\_\_\_ are fibrous connective tissue bands between plates
sutures
52
sutures allow for \_\_\_
internal expansion of organs
53
describe the layers of sutures
* inner cambian layer associated with periosteum
* outer capsular layers meet to join sutures togehter
* gives flex to the skull as bone formation proceeds
54
bone is continually destroyed and reformed. describe the differences between adult bone remodeling and child bone turnover
* adults - 5% cortical and 15% trabecular per year
* children - 30-100% of their total bone per year
55
most bone is formed around the \_\_\_, while it is mainly resorbed from the \_\_\_, allowing the marrow cavity to grown and also at points on the periosteum and within osteons
* periosteum (outside)
* endosteum (inside)
56
describe the cascade of factors that control the bone remodeling process
both cellular, systemic, and sequestered growth factors in bone matrix
57
describe the remodeling and repair of cortical bone
primary osteons replaced by secondary osteons, which are replaced by tertiary osteons, allowing bone growth
58
in bone remodeling and repair, ___ resorb bone, leaving a space which is filled by trailing osteoblasts. the osteoblasts create a ___ and lay new bone onto it
* osteoclasts
* cement line (non collagenous proteins)
59
what is the difference between cutting cone and filling cone in cortical bone osteon formation?
60
bone needs to be ___ and ___ at the same time. gradual replacement allows for this
structurally functional and growing
61
describe the bone marrow derived mesenchymal progenitors and the bone marrow derived hematopoietic progenitors
62
\_\_\_ is secreted in response to high calcium. the result is a ___ in serum calcium.
* calcitonin
* decrease
63
\_\_\_ is secreted in response to low calcium. the result is a ___ in serum calcium.
* parathyroid hormone
* increase
