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Bone Flashcards

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1
Q

What is the main functional unit of the cortical Bone?

A

Haversion System (secondary osteon)

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2
Q

What structure is the wall of the haversion system?

A

Concentric lamellae

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3
Q

Whats in the central canal of the haversion system?

A

Haversian canal, nerve and blood supply

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4
Q

What is the main cell component of the haversion system?

A

Osteocytes

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5
Q

What is between osteons?

A

Interstitial lamellae

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6
Q

What is the connection between osteons?

A

volkmanns canals

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7
Q

What are the small spaces that connect to lacunae?

A

canaliculi which are small pathways for the processes of the osteocytes

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8
Q

What is in the bone matrix?

A

Inorganic and organic matrix

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9
Q

What is the inorganic and organic matrix composed of?

A

inorganic matrix: HA

Organic: Collagen I

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10
Q

What are the 2 lineages of bone cells?

A

First: Mesenchymal lineage (give rise to osteoprogenitor cells –> preosteoblast –> osteoblast –> osteocytes and lining cell.
Second: Hematopoeitic lineage (Cells give rise to monocytes/macrophage and the osteoclasts are the mature form of these cells.)

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11
Q

What else are mesenchymal stem cells referred to as? some characteristics

A

colony forming fibroblasts. or Marrow stromal cells.
can differentiate into multiple cell types
small cell body and few cell processes.
must stain many biological markers to see what kind it is.

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12
Q

Osteoblasts

A

Bone forming cells.

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13
Q

Basic characteristics of Osteoblasts

A 
Produce a lot of alot of proteins 
Located on bone surface 
Generally cuboidal
Mononucleated 
HE staning: Basophilic cytoplasm (bc of a large amount of Rough ER--make proteins)
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14
Q

first Major functions of Osteoblasts

A

synthesize and secret extracellular matrix. and a fuck ton of other proteins.
MAKE collagen type I mainly.

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15
Q

second function of osteoblasts

A

Regulate matrix mineralization.

  1. releases matrix (osteoid) and minirlizes it by calcification. This process is regulated by osteoblasts.
  2. This is done By releasing matrix vesicles (have high CA and Phosphorous in cytosol without being saturated) into osteoid and calcifying it over time.
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16
Q

Third major function of osteoblasts

A

Regulates osteoclasts (take bone away) through molecular interactions.

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17
Q

what do osteoblasts release to regulate osteoclasts

A

RANKL: stimulates osteoclast differentiation and maturation (used for bone resorption)
OPG: binds to rankle and indirectly inhibits osteoclast differentiation. aka reduces bone resorption activity.

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18
Q

Osteocytes

A

bone-maintaining cells. Derived from osteoblasts when buried in the matrix. Located in laculae inside the matrix.

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19
Q

Most abundant cell type in bone

A

osteocytes

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20
Q

T/F Osteocytes are mononucleated

A

true

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21
Q

T/F Osteocytes have few dendritic processes

A

FALSE have multiple

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22
Q

Main function of osteocytes

A
  1. regulate osteoblasts and osteoclasts through cell processes.
  2. They maintain bone vitality and fucntion. If osteocytes are dead bone is dead too.
  3. Sense mechanical loading… decide if they should produce more bone or decrease it.
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23
Q

How do osteocytes handle mechanical loading

A

after sensing loading, they regulate bone formation/resorption mainly through the schlerostin-OPG/RANKL system.

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24
Q

Is schlerostin expressed in all bone cells?

A

no only in OSTEOCYTES

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25
Osteoclasts (8)
1. Bone resorption cells (through organic matrix degradation) 2. Largest of all bone cells 3. Located on bone surface (howships lacunae) multinucleated 4. TRAP (enzyme) positive cytoplasm 5. lots of mitochondria 6. Sealing zone (attachment and sealing) 7. Demineralize bone 8. Endocytosis of degraded products
26
Two forms of bone formation
1. one through membrane--> intramembranous ossification (directly from periosteum) 2. one through cartilage --> Endochondral ossification
27
Sutural bone formation
A special intramembranous process through sutural matrix. This bone formation is a intramem. mechanisim. very similar to periosteum. No cartilage involved.
28
Bone formation for Maxilla
Intramembranous (surface and sutures)
29
Bone formation of Mandible**
condyles through Endochondral mechansim because inside of condyles there are cartilage. but then it is intramambranous formation for bone surface.
30
Bone Modeling. What happens?
change of overall bone size and shape. It can either do bone formation or resorption in different locations
31
Bone Remodeling. What happens?
replacement of existing bone. bone formation and resorption at the SAME location but at different times. in THIS the overall shape and size does NOT change like it does in bone modeling.
32
What is important in cortical bone remodeling?
secondary osteons
33
What is missing in the trabecular bone that you see in the cortical bone?
Secondary Osteon
34
Remodeling in Trabecular bone starts at _____
bone surfaces. Osteoblasts will come and rebuild that bone in those surfaces.
35
The formation period lasts ____ than the resorption cycle.
LONGER
36
The remodeling rate in children late is lower?
false it's higher
37
The remodeling rate in trabecular bone is higher than cortical bone?
True
38
Osteoporosis
Unbalanced formation/resorption --> net bone loss
39
The part that contains teeth/roots is called ____ and the part that doesn't is called ____
Alveolar bone | Basal bone
40
T/F Alveolar and basal bones are NOT continuous
false
41
Where is the trabecular bone present in the alveolar process?
Only in the apical 1/3 of the alveolar process or under the alveolar crest in the inter-dental area.
42
The interdental Septum has two layers: ____ & ____
Bundle bone | Supporting Bone
43
What fibers are inserted into the Bundle bone
Sharpeys fiber
44
What is the borderline of the bundle bone?
PDL
45
Bundle bone-supporting bone borderline?
Cement line
46
If the bundle bone is not present the connection between the PDL and the bone will be what? what are the consequences?
It will NOT be INTACT anymore and the tooth will be loose because it is NOT anchored to the bone anymore.
47
What cells are found between the Sharpeys fibers that are inserted into the Bundle Bone?
Fibroblasts MSC Osteoprogenitor cells Vascular cells
48
What cells are found on bone surfaces?
Osteoblasts and bone lining cells
49
(alevolar bone development etc) Ebryonically, most craniofacial bones have a _____ tissue origin than ____ bones.
different | long bones
50
What is Jaw bone Mesenchyme developed from? and what arch?
Neural crest & Mesoderm | 1st branchial arch
51
What is the alveolar process most dependent on during postnatal growth?
Tooth eruption
52
Poor development of alveolar bone is known as?
Tooth agenesis
53
The alveolar process grows in what direction?
vertically.
54
Alveolar bone loss risk factors
``` Most important: Periodontal disease Tooth loss pathology systemic disease side effects of medication Trauma ortho force, parafunction ```
55
T/F : PDL fiber attachment adapts to bone modeling during orthodontic tooth movement. Ortho tooth movement is a ____ process of the alveolar bone. Due to resorption on one side, formation on the other, the interdental septum is _____, but not ____ during tooth movement.
True modeling process relocated. removed. Osteoclast on one side and osteoblasts on another side.
56
For ortho patients. Why are their teeth loose?
Because this connection between PDL and bundle bone layer on resorptive side is lost. But with time the connection will rebuild. aka after braces.
57
Source of Osteoclasts on the resorption (compression) side
1. inside the PDL there are BV and there are osteoclast progentior cells that can give rise to osteoclasts (only with light pressure) OR 2. from the bone marrow which is away from tooth rooth. **We get them by controlling the force level.
58
Are osteoclasts present in the PDL?
no not normally but during ortho tooth movement you get them .
59
In response to heavy pressure, osteoclasts were recruited from _______, the opposite side of the PDL undermining resorption
bone marrow
60
Source of osteoblasts on the formation (tension) side?
Osteoblasts already present in bone surface MSCs in the PDL MSCs in the bone marrow Bone lining cells
61
Bone as tissues are
mineralized (hard) connective tissue
62
Bone tissue formation will only form within a:
highly vascularized loose osteogenic connective tissue
63
Bone tissues are composed of:
Osteocytes
64
Osteocyte cell body is within ?
lacuna
65
Osteocyte cell processes are within?
canaliculi
66
Collagen fibers and GAGS are formed by? these are found where?
osteoblasts | these substances are found within the extracellular substance.
67
Two types of mature bone tissue
Compact bone tissue found on surface of organs covered by periosteum. Trabecular bone tissue (spongy) found inside bone organs extending from the inner surface of compact bone. Surface covered by endosteum.
68
Alveolar process is composed of
1 compact bone tissue (lamina dura/ facial and lingual cortical plates. 2 trabecular bone tissues (connects lamina dura to cortical plates. varies in distribution around dental arch.)

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