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D1 Spring - Histopathology > Week 9 - Bone Formation and Resorption > Flashcards

Week 9 - Bone Formation and Resorption Flashcards

1
Q

What is the alveolar bone also known as?

A

Cribiform plate or bundle bone

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2
Q

How is the cribiform plate formed?

A

as a result of attachment of the PDL fibers and passage of vessels and nerves into and out of the PDL

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3
Q

What is the term bundle bone referred to?

A

bone in which Sharpey’s fibers (PDL) are embedded

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4
Q

What is woven bone?

A

immature/newly formed bone in which the collagen fiber matrix is randomly oriented

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5
Q

What is woven bone associated with?

A

generally newly formed (embryologic development) or associated with healing wounds

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6
Q

How does woven bone compare to mature bone?

A
  • Has more cells per unit area
  • Contains a greater volume of non-collagenous protein
  • Forms more rapidly than mature bone
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7
Q

What is lamellar bone?

A

mature/secondarily formed bone

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8
Q

What can lamellar bone be classified as?

A

Spongy/cancellous and compact/cortical

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9
Q

What is spongiosa/cancellous bone?

A

trabecular bone that lies between the cortical plates and within the marrow spaces

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10
Q

Describe the appearance of spongiosa/cancellous bone

A
  • Trabeculae lined with osteoblasts (bone lining cells)
  • Has random orientation of collagen fibers
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11
Q

What are facial and lingual cortical plates made of?

A

Made up of lamellar bone, haversian bone, or interstitial bone

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12
Q

What is the composition of bone?

A

67% inorganic (Calcium hydroxyapatite)
33% organic
- 28% collagen
- 5% proteins (osteocalcin, sialoprotein, osteonectin, BMP)

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13
Q

What is osteoid?

A

bone matrix formed by osteoblasts (5-10 um increments)

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14
Q

What is the function of osteoblasts?

A

Make bone (active bone lining cells)

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15
Q

What is the function of osteoclasts?

A

Remove bone

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16
Q

What is an osteocyte?

A

An osteoblast that has been entrapped by its own osteoid matrix

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17
Q

What are bone lining cells?

A

Flattened inactive osteoblasts that line trabecular bone. Protect bony surface from osteoclast activity

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18
Q

What are chondroblasts?

A

Lay down cartilage

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19
Q

What are chondrocytes?

A

Maintain ECM and produce cartilage matrix

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20
Q

What are mesenchymal cells?

A

Undifferentiated cells

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21
Q

What are canaliculi?

A

how osteoblasts and osteoclasts communicate with the outside environment

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22
Q

What is the process of communication of canaliculi?

A

Processes of the osteocytes travel within the canaliculi and connect to other osteocytes/osteoblasts, allowing cell-to-cell communication

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23
Q

What other properties can the canaliculi have?

A

Mechanoreception

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24
Q

What is the periosteum?

A

A dense connective tissue, bound to bone by Sharpey’s fibers, that contains blood vessels, nerves, and three cell layers

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25
Q

What are the three cell layers of the periosteum?

A
  1. Peripheral cell layer of fibroblasts
  2. Intermediate cell layer of undifferentiated mesenchymal cells
  3. Proximal cell layer of osteoblasts
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26
Q

What is the PDL a modified version of?

A

Modified version of a periosteum

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27
Q

What does the endosteum line?

A

the medullary cavity and cancellous bone (trabeculae)

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28
Q

What is the endosteum similar in composition to?

A

Generally has the same composition as periosteum but is significantly thinner

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29
Q

What are collagen proteins associated with bone?

A

Type I
Type II
Type III
Type V
Type X

30
Q

What is the function of type I protein?

A

fibrillar; ubiquitous in distribution (located everywhere)

31
Q

What is the function of type II protein?

A

fibrillar; primarily a cartilage protein. Found in endochondral bone formation

32
Q

What is the function of type III protein?

A

fibrillar; granulation and mesenchymal tissues. Found in healing tissues

33
Q

What is the function of type V protein?

A

fibrillar, stromal connective tissue. Promotes cellular attachment and migration

34
Q

What is the function of type X protein?

A

growth plate; facilitates conversion of cartilage -> bone

35
Q

What are non-collagenous proteins associated with bone?

A

osteonectin, osteopontin, osteocalcin, BMP and others

36
Q

What are non-collagenous proteins associated with bone characterized by?

A

(all have these properties)
- Highly acidic nature
- High aggregation tendencies
- Calcium binding properties

37
Q

What does bone formation consist of?

A
  1. in-situ remodeling
  2. intramembranous bone formation
  3. endochondral bone formation
38
Q

What is in-situ remodeling?

A

a process of osteoclastic resorption, and bone replacement by osteoblast activity

39
Q

Where is in-situ remodeling mostly seen in?

A

Areas of alveolar bone affected by orthodontics

40
Q

What are the steps of in-situ remodeling?

A

Osteoclasts resorbs bone
Osteoblasts get stimulated and release osteoid
Osteoid gets mineralized and new bone is formed

41
Q

What is intramembranous bone formation?

A

bone formation within or between connective tissue membranes consisting of type I collagen (connective tissue framework that gets calcified)

42
Q

What does bone NOT replace?

A

Cartilage

43
Q

Where is intramembranous bone formation found in?

A

the inner spongy layers of bone, as well as sutures

44
Q

Describe intramembranous bone formation as a method of bone deposition

A

It is an extremely rapid and disorganized method of bone deposition, and allows for growth of the tissues surrounding it

45
Q

What is an example of intramembranous bone growth?

A

Woven bone is an example of intramembranous bone growth -> healing response

46
Q

What do osteoblasts secrete?

A

Osteoblasts secrete matrix vesicles that mineralize surrounding collagen fibers

47
Q

How are osteocytes created?

A

The osteoblasts usually become trapped themselves, becoming osteocytes

48
Q

What do matrix vesicles contain?

A

contain pyrophosphatase, **alkaline phosphatase (helps mineralize collagen), glycoproteins, phosphoproteins, phospholipids

49
Q

What is endochondral bone formatino?

A

bone formation within hyaline cartilage that involves a concomitant replacement of the cartilage framework by bone

50
Q

What type of bone formation does bone replace cartilage?

A

Endochondral bone formation

51
Q

Where is endochondral bone formation found in?

A

vertebrae, long bones, base of the skill, and head of the mandible

52
Q

What is the process of endochondral bone formation?

A
  1. Mesenchymal cells create a general outline/shape of what the final bone will look like
  2. Cells differentiate into chondroblasts (cartilage cells), which increase in size, secrete collagen, and mineralize it with matrix vesicles
    - The newly formed chondrocytes eventually die
  3. Vascular tissue from surrounding perichondrium invades cartilage, allowing chondrocytes/chondroclasts and mesenchymal cells to enter the area
  4. Chondroclasts eat away the cartilage, and newly differentiates osteoblasts deposit osteoid into the cartilage
  5. Osteoid is mineralized by osteocytes, and bone is made
53
Q

What are growth of endochondral bones dependent on?

A

the growth of the cartilage and stops once the cartilage has been completely removed

54
Q

What are the zones of cellular activity?

A
  • reserve or resting chondrocytes
  • proliferation
  • maturation
  • hypertrophy and calcification
  • cartilage degeneration
  • osteogenesis
55
Q

What kind of cartilage is in the reserve or resting chondrocytes?

A

Hyaline cartilage

56
Q

What happens during proliferation?

A

Collagen starts to form

57
Q

What happens during maturation?

A

less division of cells but chondrocytes are increasing in size

58
Q

What happens during hypertrophy and calcification?

A

where areas become evaluated (look more empty, have larger spaces)

59
Q

What happens during cartilage degeneration?

A

Chondrocytes die

60
Q

What happens during osteogenesis?

A

osteoblasts come in with capillaries. Osteoblasts differentiate and bone formation occurs

61
Q

What is bone metabolism controlled systemically by?

A

Hormones

62
Q

What is bone metabolism controlled locally by?

A

Mechanical factors, growth factors, and cytokines

63
Q

What are hormones important for?

A

Bone metabolism
- affect absorption both directly and indirectly
- Can cause both absorption or formation depending on concentration and synergy/interactions with each other

64
Q

What are examples of hormones that are important to bone metabolism?

A

Parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, Calcitonin, Estrogen, Glucocorticoids

65
Q

What do cytokines and growth factors cause?

A

osteoblasts to stimulate formation of osteoclasts. Indirectly causes bone resorption

66
Q

What are examples of cytokines and growth factors important to bone metabolism?

A

Interlukin-1, interlukin-6, BMP-2 and BMP-7, TRF, IGF, FGF, Platelet-derived GF)

67
Q

What happens under conditions that favor bone resorption?

A

Osteoblasts can be stimulated by cytokines and hormones to produce interlukin-6 which promotes differentiation of osteoblasts

68
Q

Describe osteoclast mediated resorption

A

Chemicals “wake up” osteoblasts which activates osteoclast precursors and allows activation of osteoclasts (which resorb bone)

69
Q

What does osteoclastic resorption of bone do?

A

(works like a bacteria) decreases pH to demineralized hydroxyapatite

70
Q

What enzymes work in osteoclastic resorption to degrade the bone matrix and demineralize hydroxyapatite?

A

lactic acid, citric acid, free protons/H+, **acid phosphatase, aryl sulfatase, collagenase and gelatinase

71
Q

What is the osteoclast mediated resorption reaction?

A

CO2 + H2O -> HCO3- + H+
- Carbon dioxide and water catalyzed by carbonic anhydrase. Results in bicarbonate and free protons
- Bicarbonate gets removed and free protons are there to help demineralize and break down the bone

D1 Spring - Histopathology (14 decks)

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