5.3 lect - cartilage, bone, synovial joint Flashcards
1
Q
which is the “apical” side of an osteoblast?
A
faces the osteoid
2
Q
the apical side of this bone cell is thrown into folds to increase surface area
A
osteoblast (secreting osteoid)
osteoclast has ruffle border (H+ pumps)
3
Q
what are the 3 specialized regions of an osteoclast?
A
- ruffle border (incrased surface area for H+ pumps into howship lacuna)
- sealed clear zone (actin filaments & adhesion proteins seal off active resorbing area)
- basolateral region (exocytosis of digested vesicles to enter capillaries and systemic circulation)
4
Q
what is hyaline cartilage
A
a hydrated matrix of type II collagen with entrapped chondrocytes
5
Q
while chondrocytes are found at the center of a hyaline cartilage tissue, these cells are found on the periphery
A
chondroblasts
6
Q
chondrocytes that divide after being entrapped form …
A
isogenous groups
7
Q
the cartilage matrix can be divided by staining properties into __ and __
A
- territorial matrix (rich in GAGs) near chondrocytes
- interterritorial matrix away from chondrocytes
8
Q
the dense connective tissue layer surrounding hyaline cartilage is called
A
perichondrium
9
Q
this tissue type is usually found where dense connective tissue inserts into cartilage
A
fibrocartilage
10
Q
what is contained within canaliculi?
A
processes of osteocytes
11
Q
this cell functions to secrete osteoid, pre-mineralized bone matrix
A
osteoblasts
12
Q
a quiescent osteoblast is a…
A
bone lining cell
13
Q
5 resident cells of bone
A
osteoprogenitor osteoblast bone lining osteocyte osteoclast
14
Q
this cell is responsible for resorption of bone
A
osteoclast
15
Q
how is an inactive osteoclast morphologically different from an active osteoclast?
A
inactive - mononucleated (monocyte)
active - large multinucleated (fusion of monocytes)
16
Q
how does an osteoclast resorb bone?
A
creates a sealed space, howship’s lacuna, into which H+ ions and enzymes are pumped across the ruffled border
17
Q
creates a sealed space, howship’s lacuna, into which H+ ions and enzymes are pumped across the ruffled border
A
osteoclast
18
Q
together, __, __, and __ surround the surfaces of mineralized bone
A
osteoblasts
osteoclasts
bone lining cells
(perhaps morphologically indistinguishable osteoprogenitor cells)
19
Q
T/F osteoprogenitor cells give rise to osteoclasts
A
false
monocytes do
20
Q
osteoprogenitor cells give rise to…
A
osteoblasts
osteocytes
bone lining cells
21
Q
__ bone comes about through remodeling
A
lamellar (secondary) bone
22
Q
__ bone is newly formed
A
woven (primary) bone
23
Q
how is a haversian canal formed?
A
-cutting cone of osteoclasts
-closing cone of osteoblasts
(tunneling along axis of maximal stress)
24
Q
cutting cone
A
cone of osteoclasts tunneling along axis of maximal stress to make room for a new osteon
25
closing cone
cone of osteoblasts filling tunnel created by cutting cone of osteoclasts along axis of maximal stress to make new osteon
26
what ensures patency of the bone's blood supply?
volkmann's canals growing across lamellae to join haversian canals
27
what is an "anastomosing network"
linking of streams
| e.g. volkmann's canals connect haversian canals to creat an anastomosing network of vessels
28
T/F bone is a static structure
false
| dynamic structure, constantly remodeling
29
where is cartilage present on ribs?
ventrally at connections to sternum
30
this tissue functions in:
- structure with flexibility
- structure in the context of intermittent forces (joints, respiratory system)
- shock absorption
- fast growth
cartilage
31
this tissue functions in:
- withstanding compressive and tensile forces
- levers for movement
- protection of organs
- calcium storage
bone
32
cells dispersed in an ECM =
connective tissue
33
cells of this connective tissue are not especially important to funciton
cartilage
34
"hylos" =
greek for glassy
35
hyaline cartilage matrix is composed of...
```
70% water
collagen
ground substance
glycoproteins (e.g. fibronectin)
proteoglycans
```
36
what is the predominant material in cartilage?
water
| 70%
37
why are there large vacuoles in cartilage on LM?
fixation artifact
38
T/F cartilage is avascular
true
39
this ECM component has a "bottle brush" appearance
proteoglycan aggregates
| -glycoscylations stemming / radiating out from hyaluronic acid core
40
what is a proteoglycan in the ECM?
glycoscylations stemming / radiating out from hyaluronic acid core
41
aggrecan
one type of proteoglycan aggregate
| -glycoscylations stemming / radiating out from hyaluronic acid core
42
glycoscylations stemming / radiating out from hyaluronic acid core
proteoglycan aggregate
43
proteoglycans bind...
water and collagen
44
proteoglycans have a net __ charge
negative
45
how are nutrients transported to chondrocytes?
via hydrated ECM of proteoglycan aggregates and water
| through compressive forces
46
is territorial matrix more eosinophilic or more basophilic? why?
```
basophilic
more GAGs (which are negative)
```
47
surrounds isogenous groups in hyalin cartilage
territorial matrix
48
between isogenous groups in hyalin cartilage
interterritorial matrix
49
what kind of cartilage is found in the trachea and lung airways?
hyaline cartilage
50
eustation tube
epiglottis
external ear
are made up of...
elastic cartilage
51
the epiglottis is made of...
elastic cartilage
52
cartilage with thin dark staining fibers in the matrix is probably...
elastic cartilage
53
what kind of cartilage in intervertebral disks?
fibrocatilage
| surrounding juicy nucleus pulposus
54
herniated disk
fibrocartilage in intervertebral disk tears and juicy nucleus pulposus leaks out
55
how to distinguish chondrocytes from fibroblasts in fibrocartilage?
round cells - chondrocytes
| fusiform cells - fibroblasts
56
synovial fluid consists of...
water (transudate from capillary plexus)
proteoglycans
hyaluronic acid
(secreted by B-cell synoviocytes)
57
2 layers of synovial membrane
- intimal layer (1-4 layers of synoviocytes)
- subintimal layer (fibrovascular)
* both encompassed within joint capsule*
58
intimal layer of synovial membrane
1-4 layers of synoviocytes
A-cells (macrophages)
B-cells (synovial fluid secretion)
59
T/F synovial fluid consists of a mixture of transudate from capillary plexus and ground substance
true
60
subintimal layer of synovial membrane
fibrovascular layer between intima and joint capsule
61
T/F cartilage has a highly limited capacity for repair
true
| avascular
62
T/F cells in the perichondrium have the capacity to differentiate into chondrocytes to aid cartilage repair
true
| but this capacity is limited
63
cartilage repair
- cells in perichondrium have limited capacity to differentiate into chondrocytes
- defects are often filled by fibroblasts, which produce dense scar limiting and impairing recovery of function
64
T/F any trauma to cartilage (over-training, surgery, etc) does not repair well and will probably scar
true
65
fibronectin
a glycoprotein found in round substances of connective tissues
66
what substance is exclusively found in cartilage?
- type I collagen
- fibronectin
- type II collagen
- heparin
type II collagen
67
what are the consequences of the avascular an non-innervated nature of catilage
- lower chance of transplant rejection
- poor recovery after damage
- no direct pain from damage
- diffusion from surrounding ct must supply metabolic support
68
T/F cartilage has a relatively lower chance of transplant rejection
true
| avascular and non-innervated
69
T/F no direct pain is felt from cartilage damage
true
| avascular and non-innervated
70
T/F diffusion from surrounding connective tissue supplies metabolic support to chonrocytes
true
| avascular and non-innervated
71
where does bone marrow exist?
between trabeculae of spongy cancellous trabecular bone
72
this type of bone is highly organized to confer strength without increasing weight (e.g. like the eiffel tower)
trabecular spongy cancellous bone
73
this type of bone is a three-dimensional latticework that uses arches, rods, and plates to counter forces and provide maximum support for weight
trabecular spongy cancellous bone
74
3 main parts of compact bone
outer circumferential lamellae
inner circumferential lamellae
osteons (haversian systems)
75
T/F circumferential lamellae refer to osteons
false
| surround entire inside or outside of bone
76
T/F osteons usually run perpendicular to the long axis of the bone
false
| usually run parallel to long axis of bone
77
how are adjacent lamella of an osteon oriented to one another?
90 degree angles (opposite twisting slants)
| -reason for appearance in polarizing microscope
78
what are the lamellae of the osteon?
10% water
45% organic material (mostly type I collagen, some ground components)
45% mineral (hydroxyapatite crystals Ca10(PO4)6(OH)2 )
79
what is the organic material of bone?
mostly type I collagen
some ground components
-osteonectin (binds mineral to collagen I)
-osteopontin (binds cells to matrix)
80
what is the ground substance in bone?
- osteonectin (binds mineral to collagen I)
| - osteopontin (binds cells to matrix)
81
what is bone mineral?
hydroxyapatite crystals
| Ca10(PO4)6(OH)2
82
what is hydroxyapatite?
Ca10(PO4)6(OH)2
| bone mineral
83
what is the collagen type in bone?
type I
84
how is bone mineralized?
hydroxyapetite is deposited inside type I collagen fibers, between fibrils
85
osteogenesis imperfecta
bone deprived of type I collagen elements, minerals are more brittle, bones broken more easily
86
T/F osteoblasts are interconnected by gap junctions
true
87
on EM, a cell with prominent golgi apparati beside a layer of collagen beside a layer of very dark black probably depicts...
an osteoblast next to an osteoid layer next to a mineralized bone matrix
88
T/F canaliculi are the osteocyte processes that communicate with one another in tiny canals across osteon lamellae
false
| canaliculi are the actual tunnels, not the osteocyte processes within them
89
how are osteocyte processes linked to one another?
gap junctions
90
what is one function of an osteocyte?
sense forces through the filaments connecting it to bone
91
how do bone lining cells connect to each other?
gap junctions
92
T/F gap junctions connect both bone lining cells and osteoblasts to one another
true
93
T/F you will be asked to identify osteoprogenitor cells
false
| too similar morphologically to bone lining cells
94
where are osteoprogenitor cells present?
inner cellular periosteum
endosteum
lining haversian canals
95
where do osteoprogenitor cells come from?
mesenchymal stem cells
96
osteoclasts regulate ...
calcium homeostasis
97
how do osteoclasts regulate calcium homeostasis?
low serum calcium
- thryoid secretes parathyroid horomone to inhibit osteoblasts
- osteoblasts release osteoclast stimulating factor (RANKL) to activate osteoclasts
high serum calcium
-thyroid secretes calcitonin to inhibit osteoclasts
98
how does the thyroid gland regulate calcium homeostasis?
- parathyroid hormone inhibits osteoblasts and stimulates them to release RANKL to activate osteoclasts
- calcitonin inhibits osteoclasts
99
what gland is key in regulating calcium homeostasis
thyroid gland
- parathyroid hormone inhibits osteoblasts and stimulates them to release RANKL to activate osteoclasts
- calcitonin inhibits osteoclasts
100
how does parathyroid hormone affect bone?
inhibits osteoclasts and stimulates them to release RANKL to activate osteoclasts
- increase serum calcium concentrations
- released by parathyroid gland
101
how does calcitonin affect bone?
inhibits osteoclasts
- decreases serum calcium levels
- released by thyroid gland
102
RANKL
osteoclast stimulating factor
| -released by osteoblasts in response to parathyroid parathyroid hormone
103
what is the process by which the transition from woven immature bone to lamellar mature bone accomplished?
bone remodeling
104
bone remodeling
what is the process by which the transition from woven immature bone to lamellar mature bone accomplished
105
describe bone remodeling in 3 steps
- cutting cone of osteoclasts
- vascularization
- closing cone of osteoblasts
106
what happens to osteoblasts in the closing cone during bone remodeling?
become trapped osteocytes or bone lining cells along haversian canal
107
what is the name of the structure created by a cutting cone of osteoclasts
resorption tunnel
108
T/F bone remodeling ceases when all woven immature bone has been converted to lamellar mature bone
false
| remodeling continues to respond to stressors, creating new osteons and revising structure
109
type X collagen
short chain collagen expressed by hypertrophic chondrocytes during endochondral ossification at the growth plate
110
short chain connective tissue fibers expressed by hypertrophic chondrocytes during endochondral ossification at the growth plate
type X collagen
111
how can you differentiate between an osteoblast and an osteoclast on EM?
- osteoblast: folds are not as apparent, collagen fibers in osteoid unmineralized matrix
- osteoclast: ruffled border is Very apparent, no apparent collagen fibers in demineralized matrix
112
T/F gogli aparati are apparent in EM of osteoblast but not of osteoclast
false
- osteoblast secretes osteoid and vesicles for calcification
- osteoclast repackages endocytosed vesicles for basolateral release for eventual reuptake into plasma
113
how to tell difference between osteoblast and osteocyte on EM?
-osteocyte will be completely surrounded by mineralized matrix, osteoblast will only have apical mineralized matrix
(both may have a layer of unmineralized matrix - apically for osteoblast, in lacuna for osteocyte)
