Bone Flashcards

1
Q

2 Types of Macroscopic Bone

A
  1. Cortical

2. Cancellous

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2
Q

Structure of Cortical bone

A
Osteons/Haversian systems
1. Osteon - outer border = cement lines
2. Vascular canals = Haversian canals (long axis)
Volkmanns canals (TV)
3. Interstitial Lamellae
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3
Q

Cortical bone charactertics (2)

A

Slow turnover rate

High Youngs modulus

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4
Q

Cancellous bone characteristics

A

High turnover rate

Lower Youngs Modulus

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5
Q

2 types of Microscopic bone

A
  1. Woven Bone

2. Lamellar bone

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6
Q

Lamellar vs Woven bone features

A

Lamellar = remodelled bone
Organised
Stress oriented
Stronger and less flexible;

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7
Q

Osteoblasts origin

A

Undiff mesenchymal cells

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8
Q

OB function

A

Form bone - produce non-mineralised matrix

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9
Q

CK that stimulate OB formation (4)

A

BMP - Mesenchymal - osteoprogenitor cells

  1. RUN x2
  2. CBFA (core bind fac alpha)
  3. PDGF
  4. IDGF

Bump, run and core

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10
Q

Periosteum layers (2)

A
  1. Inner cambium layer

2. Outer fibrous layer

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11
Q

OB features

A
  1. Great synthetic ability

2. High ALP activity

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12
Q

3 fates of OB

A
  1. Inactive bone lining cells
  2. Osteocytes
  3. Apoptosis
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13
Q

Osteocyte functions (3)

A
  1. Control calcium
  2. Phosphate metabolism
  3. Respond to mechanical, electrical and chemical (PTH) stimuli
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14
Q

OB receptors (2)

A
  1. PTH

2. 1,25 dihydroxyvit D

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15
Q

PTH effect on OB (2)

A

Stim production of RANKL

Jagged1- Notch immune response

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16
Q

OC origin

A

Myeloid hamatopoieitic cells

Monocyte progenitor

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17
Q

OC microscopic appearance

A

Multinucleated giant cells

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18
Q

OC: Where does bone resorption occur

A
  1. Ruffled border - Howship’s Lucunae
19
Q

How do OC attach to bone?

A

Integrins at sealing zone

avb3 –> vitronectin (on bone surface)

20
Q

How do OC absorb inorganic bone? (3)

A

LOW PH THROUGH:

  1. Carbonic anhydrase system
  2. ATP dependant proton pumps
  3. Na/H+ exchange system
21
Q

How do OC absorb organic bone? (2)

A

PROTEOLYTIC ENZYMES

  1. TRAP
  2. Cathepsin K
22
Q

Components of Organic component (4)

A
  1. Collagen I
  2. Proteoglycans
  3. Proteins (Osteocalcin, osteonectin, Osteopontin)
  4. CK and GF ( IL1,6, IGF, TGF B BMPs)
23
Q

Proteoglycan function

A

Compressive strength

24
Q

Collagen structure

A

1 x a2 2xa1 (triple helix)

25
Q

Osteocalcin produced by?

A

Mature OB

26
Q

Osteocalcin functions (3)

A
  1. Promotes mineralization
  2. Attracts OC
  3. Marker of bone turnover
27
Q

Osteonectin secreted by? @)

A

Plts + OBs

28
Q

Osteonectin Function?

A

Regulation of mineralization

29
Q

Osteopontin function?

A

Cell binding protein - anchors osteoclasts to matrix

30
Q

Inorganic bone components? (2)

A
Calcium hydroxyapatite
Osteocalcium phosphate (Brushite)
31
Q

Blood supply to bone comes from 3 main sources

A
  1. Nutrient artery
  2. Metaphyseal-Epiphyseal system
  3. Periosteal system
32
Q

Nutrient artery supplies what portion of mature bone>

A

inner 2/3 via Haversion system

33
Q

Met-epi system arises from what vascular plexus?

A

Periarticular (ie geniculate)

34
Q

Periosteal system capillaries enter at which sites?

A

Major muscle attachments

35
Q

Normal direction of blood flow in bone?

A

Centrifugal (in -> out)

36
Q

Type of blood flow after reaming + normal venous flow + immature bone?

A

Centripetal (out -> in)

37
Q

Major source of growth plate nutrition?

A

Perichondrial artery

38
Q

OB produce which substance to stimulate OC?

A

RANKL

39
Q

OB secretes which substance to inhibit OC>

A

Osteoprotegrin

40
Q

Osteoprotegrin function?

A

Binds to and sequesters RANKL

41
Q

Factors that inhibit OC (5)?

A
  1. OPG
  2. Calcitonin
  3. Estrogen (decrease in RANKL)
  4. TGF beta
  5. IL 10
Osteoclast
Cant
Eat
The
Iliac wing
42
Q

OC activation? (6)

A
  1. RANKL
  2. PTH
  3. IL1
  4. Vit D
  5. IL6 (Myeloma)
  6. MIP-1A (Myeloma)
43
Q

Bone mets mediated by which pathway?

A

RANK/RANKL