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Flashcards in Bone and Ossifciation Deck (83):
1

What is the major supporting framework of the body?

bone

2

Bone is the major reservoir for___-

calcium

3

soluable salts must be transported from blood vessels to osteocytes by...

canaliculi because deposits of calcium int he matrix prevent diffusion of soluble salts

4

what are the two forms of bone?

compact dense bone spongy trabecular/cancellous bone

5

What are the organic components of bone?

type I collagen (90%) proteoglycans and other proteins (10%)

6

What do the organic components of bone contribute to the structure?

elasticity

7

What are the inorganic components of bone?

calcium phosphate (hdyroxyapatite crystals)

8

What do the inorganic components of bone contribute to the structure?

Bone rigidity

9

What type of growth does bone illustrate?

appositional only (periosteum)

10

Periosteum surrounds

most bone except articular surfaces insertion of tendons insertion of ligaments

11

Diaphysis

shaft primarily compact bone with marrow cavity at center

12

Epiphysis

bulbous expanded ends of bone primarily spongy bone covered by thin layer of compact bone

13

metaphysis

funnel shaped region that connects diaphysis with epiphysis SPONGY BONE

14

Epiphyseal plate

separates epiphysis from diaphysis cartiligenous connected to diaphysis by spongy bone (metaphyssis) RESPONSIBLE FOR INCREASE IN LENGTH OF GROWING BONE

15

osteoclast bone reabsorbtion

acidic environment lose rigidity

16

What are the two types of bones?

Compact bones or trabecular

17

Where is the outter circuferentia lamellae?

It is located under the periosteum, and it is the external surface of the compact bone.

18

What type of bone is the intersitial lamellae?

Compact lamellae haversian

19

What type of bone is the outter circumferentia lamellae?

compact lamellae non haversian

20

What type bone is the inner circumferentia lamellae?

 

compact lamellae non haversian

21

What does non haversian mean?

 

It does not have any blood vessels in the center.

22

What type of bone is bone marrow?

Trabeclar lamellae non haverian

23

How do periosteal and endosteal communicate with the haversian canal?

Through the volksmanns canal

24

Osteonectin

It is made by osteoblast. It helps with the mineralization of the bone.

25

What type of bone is the haversian system/ osteon?

compact lamellar haversian bone

26

Where is the inner cirucmferential lamellae found

under the endosteum

27

Endosteum

lines marrow cavity and spaces in spongy bone

become osteoblast when repair is necessary (fractures)

28

Intersistial lamellae are round

between osteons and separated fromt hem by cement line

29

Outer layer of perisoteum

alot of collagen and blood vessels then penetrate volksmanns canal

few fibroblast

30

Inner layer of Periosteum

Lined with osteoproginator cells

31

Non Callgenous Matrix Proteins of bone matrix

osteocalcin

osteopontin

osteonectin

32

Osteocalin

inhbiits osteoblast function/ bone mineralization

33

Osteonectin

made by osteoblast

properties in mineralization of bone

34

What type of growth does bone exhibit 

appositional growht

35

Where are sharpeys fibers seen?

outer layer of periosteum

 

36

What do sharpays fibers do?

thick collagen fibers that penetrate outer layer of periosteum

37

How do the cirumferential lamellae (non-haversian) get their nutrients and excrete waste?

the osteocytes exchange nutrients and waste products with blood vessels in the marrow cavity

38

Where are osteoprogentiro cells found?

in inner layer of periosteum and endosteum

bone lining cells (osteocytes) but reactivate during repair of bone fractures and other injuries 

39

Where do osteocytes reside?

mature bone

lacunae of concentric lamellae 

arranged between lamellae

and interconnected by canaliculi

40

What does the cement line separate?

haversian canals from interstitial lamellae

41

osteoblast are derived from

osteoprogenitor cells

42

Osteocytes are derived from

monocyte-marcophage lineage in bone marrow

43

osteocytes become trapped in the 

calcified matrix of the lamellae (lacunae)

44

What interconnected adjacent lacunae?

canniculi

45

What type of junction interconnects canaliculi

gap junctions  (ions and low molecular weight molecules)

46

How do high moelcular weight molecules pass between cells

via diffusion through the extraceullar mediumin the canliculus surrounding the filopodia

47

Filopodia

cytoplasmic projection

48

osteopontin

formation of sealing zone

49

Bone sialoprotein

mediates binding of osteoblast to ECM through integrins

50

Osteoid

soft tissue under osteoblast

non-mineralized organic matrix

unlike bone has no calciumphosphate

51

Osteocytes are 

terminally differentiated cells in charge ofmaintaining the ECM of the bone

52

osteoblast 

synthesize osteoid 

control mineralization fo the matrix

control differentiation of the osteoclast (RANKYL)

 

53

What are hte major protein products of osteoblast

type 1 collagen

RANKL (osteoclast precursor cells)

osteocalcin-bone mineralization

osteopontin (formation of sealing zone)

bone sialprotein (mediate bonding of osteoblast to ECM through interins)

 

54

The differentiation of osteoblast to osteocytes are regulated by 

1. Bone morphogentic protein

2. Transforming growth factor beta

3. cbfa1/runx2 (Transcription factors )

4. osterix (TF)

 

 

55

Alkaline Phosphatase

ectoenzyme (surface protein)

reacts strongly with osteoblast but disappears when osteoblast ceases protein synthesis ( becomes osteocytes)

 

56

Vitamin D (osteoblast)

regulates expression of osteocalcin (mineralzation with Calcium)

57

growth hormone ( osteoblast)

produces IGF-1/somatomedian C  which stimulates growht of long bones at level of epiphyseal plate 

58

Parathryoid hormone

simtulates osteoclast of break down bone and release Calcium

59

RANKYL (osteoblast)

receptor for activation of nuclear factor kappa B ligand (nf-kb) present in osteoclast precursor cellls

60

life of bone matrix depends on 

osteocytes

61

ARe osteoclast uninuclear or multinuclear?

multinuclear 

62

Where are osteoclast found?

howships lacunae/substeocalstic compartment

63

osteoclast create what type of environment?

acidic- required for bone reabsorbtion 

64

Osteoclast reabsorbtion

dissolution of inorganic parts of bone (rigidity) bone demineralization 

H-ATPase

followed by enzymatic degradation of organic matrix (by protease cathepsin K)

65

Osteoclast 

Large

rich in mitocondria and acidified vesicles

ruffled border (active surface facing lacuna)

-multinucleated

66

Osteoclast activity is regulated by 

calcitonin 

vitamin d3

regulatory moedlcules of osteoblast and stormal cells of bone marrow

67

where is the ruffled border of the osteoclast?

basolateral domain

68

Where is the sealing zone of the osteoclast?

Apical domain

69

What contributes to the sealing zone of osteoclast

osteopontin

alpha v beta three integrin

actin

70

What mechanisms do osteoclast have to maintain

the intergrit of its ph and the cytoplasm around it?

 

HC03- / CL Exchangers to pump out bicarbonate and maintain cytoplasmic electroneutrality

cloride channels to pump out cl- and maintain the acidity of the osteoclast and howships lacune

carbonic andydrase Ii (generates prtons from  (co2+h20-> hc03- + h+) the h+ is relased to howships lacuna by h-atpase pump to create acididc environment ) 

Cathespin K released into howships lacuna to degrade epxosed organic matrix (collagen)

71

What is the purpose of the sealing zone?

 

keeps the contents inside the howships lacuna

72

Osteoblast are active in repsonse to calcium mobilzation in from the bone to blood

because it breakd down bone 

73

when there is less vitmain d what happens to osteoclast activity

it goes up 

 

74

osteoclastogenesis (osteoclast differenentiation) is triggered by 2 molecules

macrophage colony stimulating factor (MCSF)

nuclear fator kappa (NF-kb) ligand (RANKL)

75

describe osteoclast development

 

1. there is a monocyte with a MCSF receptor on it 

2. The osteoblast releases MSSF (macrophage colony stimulating factor ) LIgand which attaches to the receptor on the monocyte

3. this in turn , transforms the monocyte into a macrophage 

4. this binding induces th eexpression of RANK which will will bind to RANK ligand epressed off the surfact of the osteoblast

5. the mononucleated monocyte becuase hte mutlinucleated osteoclast precursor but still does not have the ability to absorb bone

6. The resting (nonfunctional osteoclat uncouples fromt he osteoblast)

7. osteoblast maturation is completed when the sealing zone of the ruffle border appears 

76

how is osteoclatogensis inhibited

by osteoprotegerin (from osteoblast) by blocking RANKL binding to receptor 

 

77

Osteopetrosis

 

bone fragility

high bone density due to absent osteoclastic activity 

stone like bone

lack of MCSF

 

can lead to occlusion of marrow spaces and anemia 

78

Osteoporosis

fragile bone

excessive osteoclastic activity and deficient osteoblastic activity 

Menopause- defc in estrogen 

treatment with calcium and vitamin b

79

osteomalacia

 

soft bone

defect in mineralization

vitmaind d deficiency (rickets)

chronic kidney disease

80

osteosclerosis

increased bone mass due to increase osteoblast activitiy

81

Denosumal

RANKl antibody

functions like osteoprotegerin

decreases osteoclastogenesis 

82

Intramembranous ossification

bones of

jaw

skull

 

bone is deposited directly within  embroynic connective tissue

83

Endochondrial Ossification