Skeletal System Part 1 Flashcards
1
Q
primary function of bone and cartilage
A
support and locomotion/movement
2
Q
secondary functions of bone and cartilage (3)
A
protection
mineral storage
hemopoiesis
3
Q
bone vs cartilage (rigidity)
A
bone is rigid
cartilage is semi-rigid
4
Q
both bone and cartilage are derived from
A
primitive mesenchymal cells
5
Q
relative strength of each is due to properties of (2)
A
ground substance and extracellular fibers
6
Q
cartilage is a — precursor
A
bone
7
Q
Cartilage formation begins with
A
stellate mesenchymal cells
8
Q
stellate mesenchymal cells differentiate into — —, grow & synthesize (2)
A
rounded chondroblasts
ground substance & fibrous extracellular matrix
9
Q
ground substance & fibrous extracellular matrix trap chondroblasts in
A
lacunae
10
Q
Further mitotic divisions produce clusters of mature chondrocytes, referred to as
A
isogenous groups
11
Q
isogenous groups are separated by
A
extracellular matrix
territorial vs. interterritorial
12
Q
Cartilage surrounded by
A
perichondrium
13
Q
perichondrium
A
peripheral zone of dense connective tissue, containing fibroblasts, collagen, & immature chondroblasts
14
Q
Interstitial growth
A
new cartilage forms within mass
15
Q
with interstitial growth, chondrocytes retain the ability to
A
divide
16
Q
Appostional growth
A
new cartilage forms at surface of pre-existing cartilage
17
Q
which type of growth is more common?
A
Appostional growth
18
Q
New chondrocytes derived from mesenchymal cells of inner perichondrium—differentiate first into
A
chondroblasts
19
Q
More mature chondrocytes present at center of cartilage mass, with younger cells at
A
periphery
20
Q
Cartilage is an — — —meaning most cartilage lacks blood vessels
A
avascular connective tissue
21
Q
Exchange of metabolites occurs via
A
diffusion through ground substance
22
Q
Limits thickness of
A
mature cartilage
23
Q
thick cartilage contains blood vessels in
A
2’ cartilage canals
24
Q
Cartilage contains extracellular matrix of amorphous ground substance containing
A
collagen
25
Matrix hydrated, contains ~ ---, bound to proteoglycans
60-80% H2O
26
Accounts for its (2)
flexibility, incompressibility
27
GAG’s include (3)
hyaluronic acid (non-sulfated)
chondroitin sulfate
heparin sulfate
28
Most common glycoprotein is
chondronectin
29
variable types and amounts of fibers embedded within matrix produce three types of cartilage
hyaline
fibrocartilage
eastic
30
where is hyaline cartilage found? (6)
```
articular surfaces
growth plates
nasal septum
costal cartilage (ribs)
tracheal
bronchial rings
```
31
hyaline cartilage is the precursor for
bone in most of skeleton
32
hyaline cartilage is characterized by
small aggregates of chondrocytes in amorphous matrix of ground substance, reinforced with Type II collagen fibers
33
fibrocartilage consists of
alternating layers of hyaline cartilage & dense connective tissue (contains Type I & Type II collagen); less cellular than either
34
what does fibrocartilage lack?
perichondrium
35
where is fibrocartilage found? (2)
intervertebral discs
| some articular areas
36
elastic cartilage is histologically similar to
hyaline cartilage (contains Type II collagen), with addition of large #’s of elastic fibers in extracellular matrix
37
examples of elastic cartilage (3)
external ear
auditory & Eustacian canals
epiglottis, & larynx
38
examples of fibrocartilage (4)
knee
mandible [TMJ]
shoulder
sternum (ligaments, tendons, joint capsules, pubic symphysis)
39
Repair in cartilage is limited, because repair requires blood flow
blood flow
40
repair in cartilage results in
production of dense connective tissue (fibrosis)
41
Invasion of site by blood vessels frequently results in death of (2)
chondrocytes & formation of bone
42
Tendency for all hyaline cartilage to calcify with
age
43
Tendency for all hyaline cartilage to calcify with age, via
deposition of calcium phosphate crystals within matrix
44
cartilage is eventually
replaced by bone
45
bone is a specialized support tissue—extracellular components are
mineralized
46
mineralization results in (2)
rigidity & strength
47
two main forms of bone
woven
| lamellar
48
Woven bone is
immature form characterized by random orientation of collagen fibers
49
Later remodeled into
lamellar bone
50
lamellar bone contains
concentric layers, called circumferential lamellae, with parallel collagen fibers
51
Lamellar bone can be (2)
dense & compact (e.g., cortex of long bones)
| cancellous (=spongy—at ends of bones)
52
Cancellous bone contains network of (2)
thin, bony trabeculae (=spicules) & open spaces (marrow cavity)
53
Bones in limbs =
long bones
54
Have shaft (diaphysis) composed of --- in cortex & --- in medullary cavity (marrow)—
dense, compact bone
| spongy, cancellous bone
55
bone contains (2)
red (hematopoietic) marrow or yellow (fatty) marrow
56
Ends of bones =
epiphyses
57
epiphyses are composed of
spongy, cancellous bone, covered with hyaline articular cartilage
58
Flared region between epiphysis & diaphysis =
metaphysis
59
Metaphysis contains --- --- of long bones (“physis” of radiologists)
epiphyseal plate
60
External surface of bone covered by
periosteum
61
periosteum
layer of fibrous connective tissue
62
what does periosteum contain? (2)
fibroblasts
| osteoprogenitor cells
63
Internal marrow cavity lined by
endosteum
64
Sharpey’s fibers
parallel bundles of collagen fibers, extend from periosteum or Mm tendon & insert into superficial layer of bone
65
function of Sharpey’s fibers
provide anchorage & support
66
Osteoprogenitor cells
resting mesenchymal cells
67
where do osteoprogenitor cells reside? (2)
periosteum & endosteum
68
what can osteoprogenitor cells differentiate into? (2)
osteoblasts & osteocytes
69
Osteoblasts
roughly polygonal, mesenchymal cells derived from osteoprogenitor cells
70
osteoblasts are very basophilic due to synthesis of large amounts of (2)
protein & proteoglycans
71
Osteoblasts responsible for
synthesis of extracellular matrix & collagen
72
extracellular matrix & collagen is collectively referred to as
osteoid
73
Osteoid similar to cartilage, later mineralized to form
new bone
74
Osteoblasts are responsible for calcification of matrix via secretion of
matrix vesicles
75
Contain alkaline phosphatase, bud off osteoblasts into matrix, causing
precipitation of mineral salts (e.g., Ca & PO4)
76
Osteoblasts mature into osteocytes within --- after matrix mineralizes
lacunae
77
Osteocytes
mature “bone cells”
78
Osteoclasts
large, multinucleate cells, probably derived from monocyte-macrophage lineage
79
osteoclasts are
phagocytic
80
osteoclasts are actively involved in (2)
resorption & remodeling of bone
81
osteoclasts are usually found on endosteal/ periosteal surface in depressions, called
Howship’s lacunae, or resorption bays
82
Osteoclasts function in Ca homeostasis by producing
organic acids & lysozymes that digest bone
83
Osteoclasts function in Ca homeostasis by producing organic acids & lysozymes that digest bone—secreted into ECS by
ruffled border (modified, folded plasma membrane, containing microvilli-like structures)
84
Bone serves as a reservoir for -- & functions in
Ca
| Ca homeostasis
85
Regulated by 2 antagonistic hormones
parathormone & calcitonin
86
what is parathormone secreted by?
parathyroid gland
87
what does parathormone stimulate?
osteoclasts activity, results in bone resorption
88
parathormone increases --- and decreases ---
increase blood ca levels
| decreases renal excretion by kidneys
89
what is calcitonin secreted by?
thyroid gland
90
what does calcitonin stimulate?
osteoblast activity
91
what does calcitonin inhibit?
osteoclasts, results in bone deposition
92
what does calcitonin decrease
blood calcium levels
93
somatotropin stimulates
growth of epiphyseal cartilage and bone
94
somatotrophin decreases
blood calcium
95
over secretion of somatotrophin can lead to
gigantism, or acromegaly
96
undersecretion of somatotrophin leads to
pituitary dwarfism
97
Mature, compact bone composition
~ 70% inorganic salts & 30% organic matrix
98
> 90% of organic component is
Type I collagen
99
Type I collagen is synthesized by
osteoblasts
100
GAG’s of ground substance consist mostly of (3)
hyaluronic acid & chondroitin sulfate, as well as keratin sulfate
101
Non-collagenous organic molecules include (3)
osteocalcin
osteonectin
sialoproteins
102
osteocalcin
binds intracellular Ca during mineralization
103
osteonectin
bridges/ binds collagen & minerals
104
sialoproteins
rich in sialic acid; concentrated from plasma
105
Mineralized component of bone formed by inorganic salts, 1’ Ca & P, in form of
hydroxyapatite crystals–Ca10(PO4)6(OH)2
106
Bone also has affinity for (2)
heavy metals (e.g., Pb, Hg) & radioactive isotopes
107
Compact bone contains
Haversian systems, also called osteons
108
Osteons produced via --- --- —removal of existing bone by osteoclasts and redeposition of new bone by osteoblasts
bony remodeling
109
Size of average Haversian system ~=size of
osteoclast
110
Outer margin of osteon delimited by
“cement line”
111
Followed by invasion of
empty canal by osteoblasts
