LEC45: Cartilage & Bone Flashcards
1
Q
2 structures in cartilage
A
chondrocytes: cartilage cells, extracellular matrix
2
Q
components of cartilage extracellular matrix
A
1) collagen fibers
2) ground substance
3) water
3
Q
components of ground substance of ECM?
A
proteoglycans: hyaluronic acid + core proteins + chondromucoproteins (mucopolysaccharides and GSGs)
4
Q
function of components of ground substance of ECM?
A
thicken the matrix, proteoglycans especially hold together matrix
5
Q
water’s effect on matrix shape?
A
negative charge organizes water into stiff colloidal gel; makes matrix function like shock absorber; more water = bigger matrix
6
Q
what happens to astronatus’ cartilage discs when in weightless environment?
A
discs enlarge
7
Q
what happens to our height overnight, why?
A
we grow taller because water has chance to get back into disc overnight, saps during the day
8
Q
what is lacunae?
A
artifactual appearance of chambers that chondrocyte cells occupy in cartilage; appear when cells are fixed, cells shrink away from matrix walls
9
Q
3 types of cartilage
A
fibrous, elastic, hyaline
10
Q
fibrous cartilage collagen type
A
Type I
11
Q
fibrous cartilage visible in matrix?
A
yes
12
Q
fibrous cartilage have perichondrium?
A
no
13
Q
is fibrous cartilage vascular?
A
yes
14
Q
elastic cartilage collagen type?
A
type II
15
Q
elastic cartilage in matrix?
A
yes, elastin fibers are in the matrix
16
Q
elastic cartilage have perichondrium?
A
yes
17
Q
is elastic cartilage vascular?
A
no
18
Q
hyaline cartilage collagen type?
A
type II
19
Q
how does hyaline cartilage matrix appear?
A
homogenous, because no fibrous or elastin type fibers, so looks homogenous under microscope - light goes right through
20
Q
does hyaline cartilage have perichomdrium?
A
yes
21
Q
is hyaline cartilage vascular?
A
no
22
Q
how are nutrients distributed in elastic and hyaline cartilage?
A
because avascular, nutrients must diffuse or be pumped through the matrix; so avascular cartilage size is limited
23
Q
what inhibits nutrient flow through avascular cartilage?
A
calcium, causes chondrocytes to die, hence calcium replaced by bone
24
Q
when does cartilage die, and what happens as result?
A
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
