LEC45: Cartilage & Bone Flashcards Preview

Structures: Part Deux > LEC45: Cartilage & Bone > Flashcards

Flashcards in LEC45: Cartilage & Bone Deck (143):
1

2 structures in cartilage

chondrocytes: cartilage cells, extracellular matrix

2

components of cartilage extracellular matrix

1) collagen fibers
2) ground substance
3) water

3

components of ground substance of ECM?

proteoglycans: hyaluronic acid + core proteins + chondromucoproteins (mucopolysaccharides and GSGs)

4

function of components of ground substance of ECM?

thicken the matrix, proteoglycans especially hold together matrix

5

water's effect on matrix shape?

negative charge organizes water into stiff colloidal gel; makes matrix function like shock absorber; more water = bigger matrix

6

what happens to astronatus' cartilage discs when in weightless environment?

discs enlarge

7

what happens to our height overnight, why?

we grow taller because water has chance to get back into disc overnight, saps during the day

8

what is lacunae?

artifactual appearance of chambers that chondrocyte cells occupy in cartilage; appear when cells are fixed, cells shrink away from matrix walls

9

3 types of cartilage

fibrous, elastic, hyaline

10

fibrous cartilage collagen type

Type I

11

fibrous cartilage visible in matrix?

yes

12

fibrous cartilage have perichondrium?

no

13

is fibrous cartilage vascular?

yes

14

elastic cartilage collagen type?

type II

15

elastic cartilage in matrix?

yes, elastin fibers are in the matrix

16

elastic cartilage have perichondrium?

yes

17

is elastic cartilage vascular?

no

18

hyaline cartilage collagen type?

type II

19

how does hyaline cartilage matrix appear?

homogenous, because no fibrous or elastin type fibers, so looks homogenous under microscope - light goes right through

20

does hyaline cartilage have perichomdrium?

yes

21

is hyaline cartilage vascular?

no

22

how are nutrients distributed in elastic and hyaline cartilage?

because avascular, nutrients must diffuse or be pumped through the matrix; so avascular cartilage size is limited

23

what inhibits nutrient flow through avascular cartilage?

calcium, causes chondrocytes to die, hence calcium replaced by bone

24

when does cartilage die, and what happens as result?

when calcium put down into avascular cartilage, cartilage dies; bone takes over, becomes matrix

25

where is fibrous cartilage found?

pubic symphysis, intervertebral disc, joint menisci, tendon and ligament insertions into bone, anulus fibrosis of IV discs

26

where's elastic cartilage found?

ear, epiglottis

27

where's hyaline cartilage found?

respiratory tract, ventral ends of ribs, long bone epiphyseal plates, synovial joints

28

types of cartilage cells

1) perichondrial cells
2) chondroblasts
3) chondrocytes

29

what are perichondrial cells from / what do they become?

are flat mesenchymal precursor cells, in perichondrium; differentiate into round chondroblasts

30

"peri"

periphery

31

"blast"

baby cell

32

chondroblast function

divide, grow, synthesize the matrix

33

"cyte"

mature cell

34

chondrocyte function

are trapped within, and maintain, the matrix

35

what are isogenous groups of chondrocytes

groups of chondrocytes dividing, making daughter cells for interstitial matrix around them

36

what happens spatially when isogenous groups of chondrocytes are at work?

cells working separate from each other

37

in which area of cartilage do isogenous groups of chondrocytes work?

interstitial

38

how do isogenous groups divide?

mitotic divisions of pre-existing chondroblasts

39

which way does matrix expand, why?

from within, b/c it's a pliable colloid gel

40

what is appositional growth?

perichondrial cells > chondroblasts (make matrix) > chondrocytes

41

where does appositional growth occur?

outer edges of cartilage

42

what occupies epiphyseal growth plates, what kind of growth occurs there?

cartilage
interstitial growth

43

where does long bone growth occur (region of bone)?

epiphysis
top of long bone

44

where does ossification of long bone occur?

metaphysis

45

where is growth plate re: regions of long bone?

between metaphysis, epiphysis

46

where in long bone does appositional growth occur?

epiphysis's perichondrium - cells added to the outside, make matrix, grow outside of long bone

47

steps of bone growth

1) cartilage model
2) periosteal collar forms on diaphysis
3) calcification in diaphyseal cartilage
4) blood vessels invade and form marrow cavity, eroding away middle part
5) endochondral bone formation occurs on metaphyseal cartilage and becomes ossofied b/c calcium deposited there
6) blood vessels invade, erode epiphyseal cartilage
7, 8) 2o ossification centers form in epiphyseal cartilages
8,9) epiphyseal plate forms btwn meaphysis and epiphysis
9,10) metaphysis and epiphysis fuse, epiphyseal plate disappears
10) ossification complete

48

type of cells in zone of reseve cartilage?

quiescent cells

49

tpye of cells in zone of proliferating cartilage?

making matrix so isogenous groups

50

type of cells in zone of cartilage hypertrophy

cells that've made matrix already; become isolated cells

51

what occurs in zone of capillary invasion

marrow cavity forms

52

what occurs in zone of mixed spicules

dying cartilage and newly formed immature bone present

53

what is in zone of remodeled spicules

mature bone that's taking on shape that it'll have in adult

54

7 endochondral bone formation zones

1) reserve cartilage
2) proflierating cartilage
3) cartilage hypertrophy
4) cartilage calcification
5) capillary invasion
6) mixed spicules w/ dying cartilage and newly formed immature bone
7) remodeled spicules, mature bone

55

how is bone able to be stained/on slide?

decalcify bone so can cut it

56

what happens to bone as grow older?

it's resorbed where not needed, added to where it is needed, therefore changing bone shape over time

57

what causes bone WIDTH increase?

intramembranous and appositional growth

58

what causes bone LENGTH increase?

endochondral and interstitial growth

59

bone originally forms from what?

mesenchymal tissue

60

in membrane model of bone growth, what occurs?

appositional growth, intramembranous ossification at periosteum

61

what does membrane model of growth lead to?

long bone width, remodeling shape, skull vault

62

in hyaline cartilage model of bone growth, what occurs?

interstitial growth, endochondral ossification at growth plate

63

what does hyaline cartilage model of growth lead to?

long bone length, skull base

64

intramembranous appositional ossification growth involves what?

only bone, eg skull vault

65

endochondral intersitial ossification involves what?

both bone and cartilage, eg metaphysis of long bone

66

what is major different between cartialge matrix and bone matrix?

bone matrix has crystals and therefore high mineral content, cartilage matrix does NOT have crystals and therefore has low mineral content

67

what is bone matrix comprised of?

osteoid + minerals

68

what is osteoid?

uncalcified "pre-bone" made of water, type I collagen, ground substance, + calcium + phosphate ions

69

minerals of bone matrix?

hydroxyapatite crystals Ca10(PO4)6(OH)2

70

what is unique about the length/weight of long bones?

very strong, but not very heavy because TUBULAR structure adds STRENGTH where forces are incurred (solid outer surface) but doesn’t add weight (hollow center)

71

what does cancellous mean

spongy, trabecular; meshwork of bony spicules

72

what are concentric layers of bone?

periosteum > compact/cortial bone > cancellous/spony/trabecular boney meshwork

73

cancellous bone matrix made of?

trabeculae / spicules

74

how do trabeculae arrange? Why significant?

trabeculae form right-angles to each other; prevents bone from twisting, bending breaking; distributes force over larger area to cortex

75

where does bone marrow go

in spaces between trabeculae (also fat there)

76

what occurs in osteoperosis?

trabeculae still at right angles, but become THIN - lose calcium, so framework brittle, fragile

77

where is compact/cortical bone?

in perimeter of bones

78

function of compact/cortical bone?

nearly solid; accouts for most of bone weight

79

forms of compact bone

circumferential lamellae and haversian system osteons

80

how many layers of lamellae in bone?

2 circumferential lamellae - outer and inner; also interstitial lamellae

81

fiber type of circumferential lamellae, and their arrangement?

type I collagen; in parallel layers; fibers oriented at 45 degrees relative to adjacent layers

82

fiber type and arrangement of haversian osteons?

type I collagen fibers in concentric layers, fibers oriented 45 degrees relative to adjacent rings

83

organization of cortex of bone, from outer to inner?

1) outer periosteal circumferential lamellae
2) haversian system osteons
3) inner endosteal circumferential lamella > marrow inside

84

what type of layers do osteons have?

concentric lamellae (like Onion)

85

what type of layers do periosteal circumferential lamellae have?

parallel (like Parfait)

86

what are concentric lamellae arranged around? What does it contain?

haversian canal, which has blood vessels, nerves

87

what connects adjacent Haversian canals? Function?

Volkmann's canals; allow blood vessels to get in from periphery, and in from 1 column to another; run 90o to Haversian canals; no concentric circles of lamellae

88

cartilage cell precursors?

perichondrial

89

bone cell precursors?

osteoprogenitor

90

what makes cartilage matrix?

chondroblast

91

what makes bone matrix?

osteoblast

92

what is trapped in cartilage matrix?

chondrocyte

93

what is trapped in bone matrix?

osteocyte

94

what resorbs cartilage matrix

NOTHING!

95

what resorbs bone matrix?

osteoclasts

96

osteoblasts

activated osteoprogenitor cells aka make bone

97

osteoprogenitor cell

bone lining cell that covers quiescent bone surfaces

98

osteocytes

former osteoblasts, trapped within bone matrix

99

what do osteoclasts arise from

mononuclear phagocytic system; eat old bone that needs to die, be resorbed and reformed

100

what system are osteoclasts part of?

mononuclear phagocytic system

101

bone cells' evolution

osteoprogenitor > osteoblast > osteocyte > osteoclast

102

what are osteoprogenitors derived from, where are they found, what do they give rise to?

from mesenchyme-type cells; found at periosteum; give rise to osteoblasts and osteocytes

103

where are osteoblasts, what do they do

on perimeter of matrix, lay down organic components of bone matrix

104

osteoid?

unmineralized bone

105

osteocytes' characteristics

lost their major protein syntehtic apparatus; connected to adjacent cells by long cell processes allowing cell-cell communication, ion/fluid transfer

106

what are the are bone matrix "maintenance" cells

osteocytes

107

what are canaliculi?

small channels, contain cytoplasmic processes, from osteocytes; communicate w/ other osteocytes via GAP JUNCTIONS

108

what do canaliculi do?

allow cell processes to transfer nutrients, fluid, ions, signals, wastes; connect remote osteocytes to blood vessels in central Haversian canal; help resorb surrounding bone if osteocytes die

109

what is delimiting edge?

"cement line" or boundary between osteons of adjacent HAVERSIAN SYSTEMS, formed when new bone is made, and which canaliculi don't cross

110

what is in high concentration in delimiting edge?

muccopolysaccharides

111

how do osteoclasts appear, why?

foamy, ruffled border because dissolved bone minera , highly folded surface for increased SA

112

is cartilage present in intramembranous bone formation?

no

113

what is intramembranous bone remodeling

building w/ osteoblasts on 1 side and resorption by osteoclasts on other side of bone area

114

what happens in osteoporosis re: osteoblasts, osteoclasts?

decrease in osteoblastic activity, but osteoclast numbers and activity unaffected

115

what happens to astronauts re: bones in space?

suffer bone loss due to microgravity

116

osteon "life cycle"?

1) osteoclasts make large hole in old bone; left over partial lamellae called "interstital lamellae"
2) osteoprogenitor cells migrate inf rom blood, differentiate into osteoblasts
3) osteoblasts deposit bone along perimeter of canal lumen in sequential layers, narrow lumen
4) osteocytes trapped in lacunae within lamina layers

117

relationship between bone canal size and osteon age?

large hole=younger; small hole=older

118

leftover pieces of bone called?

interstitial lamellae of old haversian system

119

whether cortical or cancellous, what are 2 bone classifications?

1) lamellar 2) woven

120

what is woven bone?

immature bone (fetal-3 yrs old); less mineral, more cellular; irregular fiber arrangement; first bone formed during fracture repair

121

immature bone (fetal-3 yrs old); less mineral, more cellular; irregular fiber arrangement; first bone formed during fracture repair

mature bone (3 yrs-adult); more mineral, less cellular; have layered fiber arrangement

122

how does lamellar bone appear under polarized light, why?

alternating light/dark pattern because collagen fibers in successive layers arrayed at 45 degrees to each other

123

what does lamellar bone have?

layers: Osteons=concentric, circumferential=parallel; spongy=parallel

124

what is first bone formed at growth sites?

woven bone, primary spongiosa

125

how are lacunae in woven bone?

randomly placed

126

nickname for woven bone, why?

"band-aid bone" b/c made quickly, slapped down at fracture repair sites

127

where can you find woven bone and lamellar bone re: compact/cortical or cancellous/spongy layers?

can find both woven and lamellar bone in both compact and cancellous layers - depends on when made, and for what

128

what do intramembranous and endochondral ossification have in common?

both involve making woven bone first and then remodeling it into lamellar bone

129

woven bone is made form which model of bone development?

either membrane or cartilage model; either way, ends up becoming lamellar bone

130

where does woven bone persist?

gamphosis (tooth-jaw), where tendon attaches to muscle

131

why might growth plate fracture result in stunted growth?

because woven bone slapped onto fracture site, causing premature ossification of cartilage, therefore stunting growth of long bone

132

phases of bone fracture repair?

1) reactive
2) reparative
3) remodeling

133

what happens during reactive phase of bone repair?

1) hematoma
2) inflammation, granulation tissue, blood vessel growth

134

what happens during reparative phase of bone repair?

1) soft callus of fibrous tissue and hyaline cartialge bridges fracture site
2) hard callus forms of woven bone - endochondrial inside callus, intramembranous outside at periosteum

135

what happens during remodeling phase of bone repair?

1) remodeling callus: woven bone replaced by lamellar bone: trabecular lamellar bone forms first, excess bone removed, trabecular replaced by compact bone, bone returns close to normal shape

136

what is rickets? What happens, why?

osteoid (so called pre bone) doesn't calcify under conditions of poor calcium and phosphate ion levels

137

normal bone matrix percent organic v mineral?

30 percent organic (water, Type I collagen, ground substance), 70 percent minerals (calcium and phosphate in hydroxyapatite crystals)

138

osteopenia?

failure of osteoid to calcify; thinning cortices, lucent metaphyseal bands results; on x-ray, bone looks very opaque rather than dense

139

what is fibrodysplasia ossificans progressive?

over-calcification; ossifies muscle and locks joints, imprisons victim in a "second skeleton"

140

what is osteogenesis imperfecta?

defect in formation of type I collagen that forms bone matrix, result is baby's extremeties positioned oddly because has multiple fractures; can be lethal

141

what influences bone formation and resorption?

parathyroid hormone (PTH)-regulates bone turnover, and Vitamin D- regulates mineralization of bone matrix

142

factors involved in bone remodeling

estrogens, calcitonin, glucocorticoids, progesterone, androgens, impact of mechanical constraints, genetic background, growth hormone, gonadotrophic (sex) hormones

143

who was adam ranier? Why does it matter?

only person to be classified as both a dwarf and giant; 3 ft 10 inches at age 21, then pituitary tumor caused overgrowth, measured 7 ft 8 inches at his death at age 51