Block IV: Hyaline Cartilage Flashcards
(77 cards)
1
Q
What is the abundant extracellular matrix of cartilage composed of?
A
More than 95% of volume. The meshwork of tension resisting collagen fibrils (Type II) and the large amounts of heavily hydrated proteoglycan aggregates
2
Q
Is there blood present in cartilage?
A
No, avascular
3
Q
The composition of the extracellular matrix is crucial to the survival of the:
A
chondrocytes
4
Q
What permits diffusion of substances within the cartilage matrix?
A
The large ratio of glycosaminoglycans (GAGs) to type II collagen fibers
5
Q
What are characteristic present in ALL connective tissues?
A
Isolated cells chondrocytes, entrapped in matrix
6
Q
What are some atypical characteristic of connective tissue?
A
- Avascular: indicative of a low metabolic rate
- Simple diffusion through matrix
- Limited capacity for repair
7
Q
Mention cartilage functions
A
- Bears mechanical stress: the extracellular matrix is solid andfirm, is both flexible and resilient.
- Allows diffusion: the large proportion of gycosaminoglycans (GAGs) to type II collagen allows for diffusion.
- Bears weight : the large number of proteoglycans aggregates, make it well adapted to bear weight.
- Shock absorber (distributes forces) and reducer of friction. It covers articular surfaces.
- Developmental model for bone: Cartilage is a key tissue in the development of fetal skeleton and in most growing bones.
8
Q
What are the types of cartilage?
A
- Hyaline
- Elastic
- Fibrocartilage
9
Q
By what is hyaline cartilage characterized?
A
matrix-containing type II collagen fibers, GAGs, proteoglycans, and multiadhesive glycoproteins
10
Q
By what is elastic cartilage characterized?
A
is characterized by elastic fibers and elastic lamellae in
addition to the matrix material of hyaline cartilage
11
Q
By what is fibrocartilage characterized?
A
abundant type I collagen fibers as well as the matrix material of hyaline cartilage
12
Q
identify
A
hyaline cartilage
13
Q
identify
A
elastic cartilage
14
Q
identify
A
fibrocartilage
15
Q
Which cartilage is the most common?
A
hyaline
16
Q
How is the matrix of hyaline cartilage and by what is synthesized?
A
It has a homogeneous amorphous matrix,
synthetized by chondrocytes.
17
Q
Why is hyaline cartilage hydrated?
A
highly hydrated to provide diffusion of metabolites (aprox.70% water).
18
Q
What provides resistance to compression in hyaline cartilage?
A
Fibers are 40% dry weight and provide shape and tensile strength
19
Q
What molecules make the hyaline cartilage matrix?
A
- collagen molecules
- proteoglycans
- multi adhesive glycoproteins
20
Q
How much % of collagen type II is present in hyaline cartilage?
A
80% of the fibril
21
Q
What other types of collagen are present in hyaline cartilage?
A
5% - III, VI, X, XII, XIV
15% - IX, XI
22
Q
Whats the function of Type IX, XI, X and VI?
A
Types IX facilitates fibril interaction proteoglycans and XI regulates fiber size approx 15%
Collagen Type VI found at periphery of chondrocyte helps to
attach cells to matrix
Type X collagen organizes the collagen fibrils into a three dimensional hexagonal lattice approx 5%
23
Q
What are the cartilage-specific collagen molecules?
A
Because types II, VI, IX, X, and XI are found in significant
amounts only in the cartilage matrix, they are referred to as
cartilage-specific collagen molecules
24
Q
Explain the % distribution of molecules present in hyaline cartilage
A
25
What kind of glycosaminoglycans (GAGs) are present in the ground substance of hyaline cartilage?
hyaluronan
chondroitin sulfate
keratan sulfate.
26
Which is the most important proteoglycan monomer in hyaline cartilage and describe it
aggrecan. It has a molecular weight of 250 kDa. Each molecule contains about 100 chondroitin sulfate chains and as many as 60 keratan sulfate molecules.
Aggrecan molecules have sulfate groups negatively charged and have an affinity for water.
27
What is hyaluronan?
Each linear hyaluronan molecule is associated with more than 300 aggrecan molecules, forming the aggrecan– hyaluronan aggregates
28
Whta are multiadhesive glycoproteins?
Are noncollagenous and nonproteoglycanlinked glycoproteins that Influence interactions between chondrocytes and the matrix
29
what are the clinical value markers of cartilage turnover and degeneration?
Found in multiadhesive glycoproteins:
-anchorin CII
-Firbonectin
-tenascin
30
What is the function of anchorin CII?
(cartilage annexin V) functions as a collagen receptor on chondrocytes (STABILIZES CHONDROCYTES)
31
What is the function of fibronectin and tenascin?
they help anchor chondrocytes to the matrix
32
What are chondrocytes?
specialized cells that produce and maintain the extracellular matrix
33
What is the cell line that develops into cartilage?
-growing cartilage
-chondroblast
-chondrocytes
34
What do chondroblasts do?
secretes matrix which surrounds cell and forms lacuna
35
What do chondrocytes do?
mature cells that secrete matrix and metallaproteinases (MMP) is the enzyme which degrades matrix, allowing cells to reposition
themselves during growth
36
What are isogenous groups?
recent mitotic activity (makes hyaline cartilage grow)
37
identify
growing cartilage
chondroblast
chondrocyte
38
Where does hyaline cartilage start to develop, by which factor and by what is it highly regulated and influenced?
develops in mesenchymal condensations
Transcription factor SOX-9 : triggers cell differentiation into
chondroblasts which secrete matrix.
As matrix increases cells move apart and become chondrocytes. Highly regulated and influenced by biomechanical stresses
39
What is interstitial growth?
mitotic division of chondrocytes
40
identify
hyaline cartilage
41
identify
chondrocyte with negative golgi, rER abundant and basophilic stain.
Chondrocytes that are active in matrix production display areas of cytoplasmic basophilia, which are indicative of protein
synthesis, and clear areas, which indicate their large Golgi apparatus
42
What do chondrocytes secrete?
collagen and all of the glycosaminoglycans and proteoglycans
43
How does older, less active cells (chondrocytes) appear?
the Golgi apparatus is smaller; clear areas of cytoplasm, when evident, usually indicate sites of extracted lipid droplets and glycogen stores
44
identify
chondrocyte
45
What are the components of mature cartilage growth?
1- Appositional growth: cell division in perichondrium’s inner layer called chondrogenic layer (The outer perichondrium is a fibrous layer of dense connective tissue)
2- Interstitial growth: mitotic division of chondrocytes within cartilage matrix (isogenous groups)
46
How are the components of the hyaline cartilage matrix?
Not uniformly distributed
-capsular matrix
-territorial matrix
-interterritorial matrix
47
describe capsular matrix
(pericellular) is high in proteoglycans and collagens VI (binds to integrin receptors) and
type IX (regulates fibril formation)
48
describe territorial matrix
is high in collagens type II and IX and fewer proteoglycans
49
describe interterritorial matrix
more fibrils and still fewer proteoglycans
50
identify
51
What does hyaline cartilage form in fetus?
model of skeleton and persists as growth plates until long bone growth ceases
52
what is the remnant of hyaline cartilage in adults
articular cartilage in diarthrodial (synovial) joints and rib cage (costal) tracheal, bronchi, laryngeal, and nasal cartilages.
53
identify
Hyaline cartilage, capsular matrix, territorial, interstitial
54
identify
55
Why is hyaline cartilage matrix highly hydrated?
to provide resilience and diffusion of small metabolites; From 60% to 80% of the net weight of hyaline cartilage is intercellular water.
These large hydrodynamic domains in the matrix are accountable for imparting
resilience to the cartilage.
56
What is the network of collagen type II fibers in hyaline cartilage responsible for?
The network of collagen type II fibers is not only responsible for hyaline cartilage
shape and its tensile strength but also provides a framework to resist the
swelling pressure from aggrecan molecules. Some of the water is bound loosely
enough to allow diffusion of small metabolites to and from the chondrocytes
57
What is internal remodeling?
a process in which cartilage undergoes continuously as the cells replace matrix
molecules lost through degradation. Matrix turnover depends on the ability of the
chondrocytes to detect changes in matrix composition. The chondrocytes then
respond by synthesizing appropriate types of new molecules.
58
What do pressure loads do?
Pressure loads applied to the cartilage, as in synovial joints, create mechanical,
electrical, and chemical signals that help direct the synthetic activity of the
chondrocytes.
59
How can cartilage repair occur?
Some repair can occur if involves the perichondrium. The pluripotential progenitor cells can produce a few cartilage cells.
Cartilage repair is a balance between deposition of type I collagen and expression of cartilage-specific collagens. Frequently scar connective tissue and blood vessel can form occur.
60
What does lack of repair in cartilage can cause?
can cause significant problems in cardiothoracic surgery, when costal cartilage must be cut to enter the chest cavity.
61
Explain aging cartilage
cells loose ability to respond to mechanical, electrical and chemical signals. The cells hypertrophy and die, the matrix calcifies (may be replaced by bone)
62
idenitfy
cartilage repair
63
What is the precursor of bones?
In early fetal development, hyaline cartilage is the precursor of bones that
develop by the process of endochondral ossification.
Long bones are represented by cartilage models that resemble the shape of the
mature bone. During the developmental process, in which most of the cartilage is
replaced by bone.
64
What is epiphyseal growth plates?
Cartilage at the proximal and distal end of the bone serves as growth sites called epiphyseal growth plates
65
identify
Cartilages that form the initial skeleton of the foot
66
What is the articular cartilage?
The cartilage of the epiphyseal plate disappears when lengthwise growth of the bone is completed, but the articular cartilage remains throughout life. The spaces within the bone are occupied by marrow.
67
Whats the difference between articular and hyaline cartilage?
articular surface has no perichondrium, cant regenerate
68
explain the articular cartilage zones
This diagram shows the organization of the collagen network and chondrocytes in the various zones of articular cartilage. b. Photomicrograph of normal articular cartilage from an adult. The superficial zone (SZ) exhibits elongated and flattened chondrocytes. The intermediate zone (IZ) contains round chondrocytes.
The deep zone (DZ) contains chondrocytes arranged in short columns. The calcified zone (CZ), which borders the subchondral bone, exhibits small chondrocytes surrounded by the calcified matrix. Also, this zone is lighter staining than the matrix of the more superficial zones. The tidemark separates calcified zone
from subchondral bone
69
What does osteoarthritis affect?
Degenerative joint disease related to aging, most individuals over
65 show some degree of osteoarthritis.
Affects joint of knee, hips, lower vertebra, foot etc.
In early stages superficial layers are disrupted, eventually destruction of cartilage occurs.
70
Why are chondrocytes important in osteoarthritis?
Chondrocytes play an important role in the pathogenesis of osteoarthritis. By producing interleukin-1 (IL -1) and tumor necrosis factor α (TNF -α), the production of metalloproteinases is stimulated, whereas synthesis of type II collagen and
proteoglycans by the chondrocyte is inhibited. Matrix is deteriorated; leading to long-term disability
71
What does rheumatoid arthritis cause?
is a more severe form where the immune system attacks the cartilage, bone and synovial membrane
72
What hormones stimulate cartilage histogenesis (hyaline cartilage)?
Thyroxine, testosterone, somatotropin
73
What hormones inhibit cartilage histogenesis (hyaline cartilage)?
Cortisone, hydrocortisone, estradiol
74
What does Hypovitaminosis A do to hyaline cartilage?
diminishes thickness of epiphyseal plates
75
What does Hypervitaminosis A do to hyaline cartilage?
accelerates ossification of epiphyseal plates (acne treatment alter growth)
76
What does Hypovitaminosis C do to hyaline cartilage?
Stops matrix production, distorts cartilage columns in epiphyseal plates and scurvy develops
77
What does Hypervitaminosis C do to hyaline cartilage?
Deficient absorption of calcium and phosphorus, calcium proliferates but matrix fails to calcify AND rickets develop
