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Histology - Exam 2 > Exam 2 - Osteochondrogenesis and Joint Components > Flashcards

Exam 2 - Osteochondrogenesis and Joint Components Flashcards

1
Q

bone histogenesis

A

occurs by intramembranous and endochondral bone formation - both produce bone that appears histologically identical

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2
Q

bone remodeling

A

combo of bone formation and resorption that occurs throughout life: old osteons constantly replaced as osteoclasts form an erosion tunnel, apoptose after 2 weeks, then osteoblasts form new osteon

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3
Q

where does bone remodeling occur

A

inside compact bone and at bone surfaces

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4
Q

speed of bone remodeling: primary vs. secondary bone

A

slower process in secondary bone than primary bone

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5
Q

composition of old osteon

A

high mineral content, low water content

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6
Q

relationship b/w bone and calcium

A

bone is buffer for calcium - [calcium] determined by rate at which calcium enters and leaves bone

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7
Q

cementing/reversal line

A

line of cementing substance put down by osteoblasts first - highly mineralized with little collagen

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8
Q

bone turnover in adults?

A

about 10% each year

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9
Q

what bones form by intramembranous bone formation?

A

flat bones: skull, facial bones, mandible, clavicle, pelvis - occurs in highly vascular mesenchymal tissue

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10
Q

what signaling patterns control intramembranous bone formation?

A

signals from polypeptides of Wnt, hedgehog, fibroblast growth factor (FGF), and transforming growth factor-Beta families

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11
Q

does intramembranous bone formation ever occur in endochondral bone?

A

yes - with healing of mild fractures

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12
Q

IBF - what forms primary ossification centers?

A

mesenchymal cells condense into primary os centers

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13
Q

what do mesenchymal cells in primary os centers differentiate into?

A

osteoblasts that begin secreting osteoid collagen

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14
Q

IBF- what happens after osteoblasts become trapped in matrix?

A

become osteocytes - small spicules of developing bone unite to form trabeculae

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15
Q

IBF- what does fusion of bony trabeculae form?

A

spongy bone

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16
Q

IBF- what happens once spongy bone is formed?

A

blood vessels invade and other undifferentiated mesenchymal cells give rise to bone marrow

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17
Q

IBF- where do the periosteum and endosteum differentiate from?

A

areas of mesenchymal tissues that do not undergo ossification

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18
Q

IBF- initial woven bone is turned into what in the outer and inner layers?

A

outer layer - converts to lamellar bone; inner layer -remains spongy (diploe)

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19
Q

what bones form by endochondral bone formation?

A

long bones

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20
Q

EBF- what is the purpose of hyaline cartilage?

A

serves as a small model for bone and as scaffold for bone development (bone follows cartilage)

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21
Q

EBF- what are the two stages?

A

development of primary and secondary ossification centers

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22
Q

EBF- Where does the primary os center develop?

A

at midriff of diaphysis of cartilaginous model

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23
Q

EBF- How is perichondrium turned into periosteum?

A

vascularization of perichondrium transforms chondrogenic cells to osteoprogenitor cells then osteoblasts (now periosteum)

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24
Q

EBF- what do osteoblasts first produce on surface of cartilaginous model?

A

subperiosteal bone collar by intramembranous bone formation

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25
Q

EBF- what causes cartilage matrix in diaphysis to begin to calcify?

A

chondrocytes become hypertrophic and secrete collagen X and VEGF

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26
Q

EBF- how does cartilage calcification affect chondrocytes?

A

calcified cartilage matrix inhibits nutrient diffusion and hypertrophied chondrocytes die

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27
Q

EBF- what forms the primitive marrow cavity?

A

lacunae becoming confluent when hypertrophied chondrocytes die due to inhibited nutrient diffusion

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28
Q

EBF- what do osteoclasts do with the bone collar?

A

create perforations in it, permitting periosteal buds to enter primitive marrow cavity in cartilage model - cartilage in walls of these spaces now becomes calcified

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29
Q

EBF- what are contained in periosteal buds?

A

blood vessels, osteoprogenitor cells, mesenchymal cells

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30
Q

EBF- where is osteoid/bone matrix made?

A

made/calcified on surface of calcified cartilage, forming a calcified cartilage-calcified bone complex

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31
Q

EBF- what happens after formation of the calcified cartilage-calcified bone complex begins to form?

A

subperiosteal bone collar thickens and elongates toward epiphyses

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32
Q

EBF- how do osteoclasts affect the calcified cartilage-calcified bone complex?

A

they begin to resorb the complex and enlarge the marrow cavity

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33
Q

EBF- describe the direction of bone formation

A

spreads from primary os center towards epiphyses

34
Q

how does calcified cartilage stain

A

basophilic

35
Q

how does calcified bone stain

A

acidophilic

36
Q

EBF- Where and when do the secondary os centers form?

A

at epiphyses after diaphyseal os centers well established - when osteoprogenitor cells invade epiphyses and differentiate into osteoblasts

37
Q

EBF- How do secondary os centers form?

A

similarly to primary ossification

38
Q

EBF- where is cartilage located after the epiphyses are filled with bone tissue?

A

articular surfaces and epiphyseal plates

39
Q

Epiphyseal plate growth?

A

new cartilage added to epiphyseal end while being replaced at diaphyseal end

40
Q

How does articular cartilage contribute to bone growth?

A

it doesn’t

41
Q

closing of growth plates

A

diaphyseal and epiphyseal bone become continuous, connecting the two epiphyseal marrow cavities - around 20 y/o

42
Q

zone of reserve?

A

small, randomly arranged, inactive chondrocytes at the front edge of growth

43
Q

zone of proliferation?

A

interstitial growth - region of rapid mitotic divisions that gives rise to rows of isogenous cell groups

44
Q

zone of hypertrohpy and maturation?

A

region where the chondrocytes are enlarged

45
Q

zone of calcification?

A

region where remnants of cartilage matrices become calcified and chondrocytes die

46
Q

zone of ossification/resorption?

A

where bone is made upon the calcified cartilage, followed by resorption of calcified bone-calcified cartilage complex

47
Q

signaling molecule in epiphyseal growth plate?

A

type 10 collagen

48
Q

what does bone fracture damage?

A

bone matrix, bone cells, and blood vessels

49
Q

what is bone fracture accompanied by?

A

localized hemorrhaging and blood clot formation

50
Q

what is the first step of fracture healing?

A

proliferation of osteoprogenitor cells from periosteum and endosteum surrounding fracture

51
Q

what do the osteoprogenitor cells produce at the fracture site?

A

cellular tissue surrounding fracture and penetrating b/w ends of damaged bone - forms callus internally and externally

52
Q

what forms in fracture zone after callus?

A

fibrous CT and hyaline cartilage

53
Q

what replaces cartilage at the fracture zone?

A

bone from endochondral bone formation replaces cartilage w/ mostly woven bone to form a bony callus

54
Q

what is the fate of the bony callus?

A

it is resorbed and replaced with secondary/lamellar bone as the fracture heals

55
Q

how do hairline fractures heal?

A

via intramembranous bone formation that occurs at the periosteal surface - tends to be a slower process

56
Q

synarthroses

A

immovable joints composed of CT, cartilage, or bone

57
Q

synarthroses locations

A

unite first rib to sternum and connect skull bones

58
Q

amphiarthroses

A

joints with slight movement

59
Q

amphiarthroses locations

A

IV discs

60
Q

diarthroses

A

synovial joints - permit maximum movement

61
Q

diarthroses locations

A

unite long bones

62
Q

what are diarthroses surrounded by?

A

2-layered capsule that encloses and seals articular cavity - external capsular layer and internal capsular layer

63
Q

what is contained in the capsule of diarthroses?

A

synovial fluid

64
Q

synovial fluid

A

colorless, viscous fluid that lubricates joints

65
Q

what does synovial fluid contain?

A

rich in hyaluronic acid and proteins

66
Q

external/fibrous capsular layer composition

A

fibrous layer of dense CT

67
Q

internal/synovial capsular layer composition

A

3-4 cell deep layers of type A and B cells

68
Q

what is the internal capsular layer lined by?

A

squamous to cuboidal cells on internal surface

69
Q

is internal capsular layer true epithelium?

A

no

70
Q

internal capsular layer function?

A

permits diffusion of nutrients to hyaline cartilage from synovial fluid

71
Q

what do cells in the synovial fold produce?

A

synovial fluid

72
Q

type A cells

A

phagocytic cells w/ well-developed golgi and many lysosomes

73
Q

type B cells

A

cells resembling fibroblasts w/ well-developed rER - probably secrete synovial fluid

74
Q

osteopetrosis

A

hereditary disease - abnormal osteoclast fxn leads to brittle and easily broken bones, lack of remodeling, undeveloped marrow cavity

75
Q

what type of bone is present most in osteopetrosis?

A

woven (lack of remodeling)

76
Q

albers-schonberg disease

A

marble bone disease - deficiency in CA II -> osteoblasts can’t accumulate H+ in Howship’s lacunae to activate lysosomal enzymes

77
Q

osteoporosis

A

loss of bone mass - primarily trabecular

78
Q

osteoporosis in PMS women: rates of resorption vs formation?

A

mainly normal rate of resorption and decreased bone formation

79
Q

how does rheumatoid arthritis begin?

A

inflammatory rxn in synovial tissue

80
Q

what does rheumatoid arthritis pathology involve?

A

activation of CD4+ T cells (unknown antigen)

81
Q

what do T-cells produce in rheumatoid arthritis?

A

IL-15 - stimulates synovial macrophages to produce proinflammatory cytokines and metalloproteases

82
Q

what proinflammatory cytokines does IL-15 stimulate production of in rheumatoid arthritis?

A

TNF-a, IL-1, IL-6

Histology - Exam 2 (6 decks)

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