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Oral Bio Quiz 4 > Bone > Flashcards

Flashcards in Bone Deck (59):
1

What is bone composed of?

Similar to dentin (but not anatomically)

HA overlaid on a collagen I scaffold

-67% - Inorgo - HA

-33% - Orgo
—28% - Collagen
—5% - Noncollagenous proteins

2

What are the non-collagenous proteins in bone?

Bone sialoprotein (BSP)

Osteopontin (OP)

Osteocalcin (OC)

Osteonectin (ON)

Matrix extracellular phophoglycoprotein

3

What 3 cell types are in bone?

Osteoclasts

Osteoblasts

Osteocytes

4

What are 4 physiological roles of bone?

Structural

Ca2+ homeostasis

Reservoir for growth factors in tissue repair

Hematopoietic and mesenchymal progenitor cell populations in marrow

5

Calcitonin does what?

Removes Ca2+ from blood and put it into bone

6

PTH does what?

Takes Ca2+ from bone and puts it into blood

7

What is the macrostructure of bone?

Outer layer of dense, compact (cortical) bone, with an inner cavity

Inner cavity with marrow, red or yellow, and cancellous trabecular bone

HIGHLY VASCULAR

8

T/F - Cholera diarrhea disturbs Ca2+, drops significantly, and is pretty much plasma diarrhea.

TRUE

9

What are the 3 organizational units of compact bone?

Circumferential - Outer ring of bone tissue

Concentric (osteonic) lamellae - Intact osteons

Interstitial lamellae - Fill space b/t concentric lamellae, former concentric lamellae

10

What is the basic functional unit of compact bone?

The osteoblasts

11

Look at slide 6. Picture of bone with labels

Do it

12

An osteon is formed from?

Concentric lamellae

Basically concentric rings of bone, built around a canal housing a capillary (Haversian Canals)

13

What links Haversian canals?

Volkmann canals

14

What heals faster, bone or cartilage?

Bone
-It is much, much more vascular than cartilage

*Where there is blood, there is healing*

15

Where is cancellous bone found?

Spongy bone

End of long bones, in apposition to jts and is associated w/ the marrow spaces

16

What does cancellous bone do?

Provides structure support for marrow tissues, highly vascular

Site of blood cell production, supports mesenchymal and hematopoietic progenitor cell populations

17

Layers of bone from outside in.

Periosteum

Outer Circumferential lamellae

Osteonic lamellae

Haversian canals

Inner circumferential lamellae

Endosteum

Marrow cavity with trabecular bone

18

How is the periosteum connected to the outer surface of bone?

SHARPEY’S FIBERS

Outer fibrous layer and inner layer in apposition to the bone surface

19

Which layer of the periosteum is highly cellular and vascularized, outer or inner?

Inner layer

20

What is endosteum?

Loose connective tissue covering the inner surface of both cancellous and compact bone

Separates the marrow from the bone

21

*T/F - Volkmann’s canals connect osteons, while osteons are built around Haversian canals.*

TRUE

22

What are osteoblasts?

Bone forming cells with MESENCHYMAL origin

23

What are osteocytes?

Bone cells
-Encapsulated osteoblasts
-Housed in osseous lacunae

24

What are osteoclasts?

Cells which break down bone tissue. HEMATOPOIETIC origin

25

Osteoblasts, clasts, and cytes are responsible for what?

Bone formation, repair, and maintenance

26

Tell me more about osteoblasts.

Mononucleated cells that synthesize osteoid matrix

MESENCHYMAL origin (Ectomesenchymal in the head)

Differentiate in response to a cascade of growth factors

Bone formation and repair

Communicate with each other via gap junctions, do NOT form complexes

27

T/F - Osteoblasts produce osteoid matrix similar to odontoblasts.

TRUE

28

Osteoblasts secrete what?

Collagen

Non-collagenous proteins via vesicles

Growth factors
TGFbeta1, BMP2, IGF I and II, PDGF, FGF)

Once bone is formed, they flatten and from bone lining cells

29

What are osteocytes?

Osteoblasts which have been embedded into the bone matrix

They are the endgame of healthy osteoblasts

30

What do osteocytes occupy?

Lacunae in bone tissue

Interact with each other

31

What are osteoclasts?

Fusion of monocytes

HEMATOPOIETIC ORIGIN

32

What do osteoclasts do?

Resorption of bone

Activated in inflammation
-IL-1beta, TNFalpha

Key marker
—Tartrate Resistant Acid Phosphatase (TRAP)

33

How are osteoclasts attached to surface?

Integrin, cytoplasm adjacent to surface rich in talin, actin, and vinculin

Form a ruffled border in apposition to bone

Form resorption pits (Howship’s lacunae)
-Secrete H+ ions and matrix degrading enzymes

34

What is osteoid?

Bone protein, unmineralized

35

What is the zone b/t Howship’s lacunae and intact bone?

Lamina limitans

36

Osteoblasts/osteoclasts are supplied by what?

Progenitor cell populations

Differentiate in response to signaling cascades

Also triggered by tissue damage, inflammation, repair signals

37

What is bone formation controlled by?

Complex interactions b/t osteoblasts and osteoclasts

Balance b/t synthetic and resorptive signals

Osteoblasts regulate osteoclast fx RANK-RANKL-OPG system

38

What is RANKL?

Receptor Activated Nuclear Factor kappaB Ligand

*OSTEOBLASTS*

39

What is RANK?

Receptor Activated Nuclear Factor kappaB

*OSTEOCLASTS*

40

What is OPG?

Osteoprotegerin

*Produced by osteoblasts binds RANKL*

41

Bone development types.

Endochondral bone formation
-Long bones

Intramembranous ossification
-Bones of the skull

Sutural bone growth
-Fusion of skull plates

*These are not necessarily exclusive processes

42

What is the most important factor in ossification?

Vascular supply

43

Tell me about endochondral formation.

Bone formed on a hyaline cartilage pattern

Condensation of mesenchymal cells into chondrocytes

Collagen is secreted, mineralizes, and is broken down by chondroclasts
—This allows for penetration of vasculature

44

With vasculature comes from ________ cells which differentiate into osteoblasts.

Mesenchymal

45

What makes up the primary spongiosa?

Bone matrix surrounds remaining mineralized collagen which forms mixed spicules

46

__________ gradually remove mineralized cartilage and develop marrow cavity.

Osteoclasts

47

Secondary growth centers from what?

Epiphyses of long bones
-Growth plates

48

*Tell me how PTH leads to resorption. THIS IS IMPORTANT*

PTH activates osteoblasts

Osteoblasts express higher levels of RANKL

RANK on Osteoclast binds to RANKL

This leads to resorption

49

*Tell me about PTH and quiescence. THIS IS IMPORTANT*

PTH activates osteoblasts

RANKL is blocked by OPG (OPG is produced by osteoblasts)

OPG binds RANKL and competes with RANK

This is a negative feedback loop

This leads to quiescence

*SLIDE 18*

50

Tell me about intramembranous formation.

Mesenchymal cells condense in fibrous CT, differentiating into osteoblasts and forming an ossification center

Osteoid is secreted into the CT matrix and is penetrated by bvs
-Rapid formation of mineralized woven bone

Woven bone is remodeled into mature trabecular bone w/ a collar of cortical bone around it

51

Tell me about sutural bone growth.

Fusion of skull plates

Sutures are fibrous CT bands b/t plates
-Allows for internal expansion of organs

Inner Cambrian layer associated with periosteum

Outer capsular layers meet to join sutures together

Gives the skull some “flex”

52

Children bone turnover ___-_____% of their bone per year.

30-100%

Also addition to bone

53

T/F - Adult bone turnover - 5% cortical and 15% trabecular per year.

TRUE

Mostly just remodeling

54

Most bone is formed around the _______, while it is mainly resorbed form the _______.

Periosteum

Endosteum

55

What oversees bone remodeling and repair?

Cascade of factors
-Growth factors

56

What happens in remodeling of cortical bone?

Primary osteons replaced by secondary osteons, which are replaced by tertiary osteons

Allows for bone growth

57

__________ resorb bone, leaving a space which is filled by trailing ___________.

Osteoclasts

Osteoblasts

58

Osteoblasts create a _________ line (of what?) and lay new bone onto it.

Cement

Non-collagenous proteins

59

T/F - Osteons must be first broken down to put a new osteon in that spot.

TRUE

There is also a cutting cone v filling cone where the leading edge is the osteoclasts and trailed by osteoblasts