Chapter 7 - Cartilage Flashcards
What is the progression of a cartildge cell starting as MSC?
MSC -> Condragenic cell -> Condroblast -> trapped in ECM -> Condrocyte
Is cartilage vascular? What does this mean for the ECM?
Cartilage is avascular which means nutrients and waste must move through the ECM. Which means the ECM must be very hydrated and move slowly
What are the 2 functions the hydrated ECM serve?
- Allows for the diffusion of nutrients etc
- Increases pliabilty
What are the two main compotnent of cartilage? At what percentages?
- Condrocytes
- ECM (95%)
What are condrocytes trapped in?
Lacunae
What in the ECM allows it to draw in water?
The ECM has high GAG and proteoglycans which are anionic, draw in cations, which draw in water
What are the three types of cartilage?
- Hyaline
- Elastic
- Fibrocartilage
Which cartilage(s) are surrounded by a perichondrium?
- Hyaline
- Elastic
What makes up the ECM of hyaline cartiledge?
- Type II collagen
- GAGs and proteoglycans
- Multi-adhesive protiens
What is the perichondrium?
It is the site of growth, it houses chondragenic cells
Where is hyaline cartilage found?
- Fetal skeletal tissue
- Rib cage
- Nasal vavity, larynx, trachea
- Articular Cartilage
What type of cartilage is articular cartilage? What is it’s function? Where is it located?
Hyaline Cartilage
Found on the joints of long and short bones
Allows for smooth, fluid movement
What is the ECM made of in Elastic cartilage?
Same as hyaline (II collagen, GAGs, proteoglycans,multiadhesive protiens)
PLUS elastic fibers
What do the elastic fibers in elastic cartilage ECM do?
They increase stretching capacity
Where is elastic cartilage located? (3)
- External ear
- Epiglottis
- Auditory tube
What does fibrocartilage lack that the other two have?
A perichondrium
What makes up the ECM of fibrocartalidge?
Same material as hyaline cartidage (Type II collogen, GAGs, progetoglycans, multiadhesive protiens)
PLUS type I collogne
What function does the type I collagen fibers in fibrocartilage serve?
It increased the strength and allwos for increased impact
Where is fibrocartalege found? (3)
Invertebral discs
Meniscis (knee)
Pubic symphysis
What causes asteoarthritus?
Cartilage wears away which leads to bone on bone interactions -> inflammation and damage
What are the 4 functiosn of hyaline cartilage?
- Resist compresion
- Provide cushion and low-friction surface
- Structural support
- Foundation for development of fetal skeleton
What are the 3 compotents that make up hyaline cartilage?
- Matrix / ECM
- Perichondrium
- Chondrocytes in lacunae
What are the two main types of collagen found in hyaline cartilage? What are their functions?
- Type II - strength
- Type IX - anchor down components of matrix to create the fluid network
What is an aggrecan? What purpose does it surve in hyaline cartilage matrix?
A primary protetoglycan with chondroitin and keratan sulfates
Sulfates carry a neg charge –> –> water
What do mutli-adhesive glycoprotiens do?
Act as glue that hold the components of the matrix together
What are the two types of multi-adhesive glycoprotiens that are found in hyaline cartilage matrix? What do they do?
- Anchorin CII - allows to attach to fibers in matrix
- Fibronectin - anchors chondrocytes to matrix
What are the compotents of hyaline cartilage? (5)
- Water (60-80%)
- Collagen (15%)
- Aggrecans (9%)
- Multi-adhesive protiens (5%)
- Condrocytes (3-5%)
What are the two layers of the perichondrium?
- Outer Fibrous layer: fibroblasts, make type I collagen
- Inner chondogenic layer: condrogenic cells that differentiate into condroblasts and then into condrocytes
What is the perichondrium?
Dense irregular collagenous CT membrane that surround cartilage on the ourside
What two cartilages don’t have a perichondrium?
Articular Cartilage
Fibrocartilage
When chondrocytes group together what are they called?
Isogenous groups
What do chondrocytes do?
Synthesize and maintian the ECM
What gives chondrocytes thier vaculoe apperence or emptiness?
High glycogen and lipid stores
What are the 3 zones of matrix materials between chondrocytes?
- Pericellular/capsular matrix
- Territorial matrix
- Interterritorial matrix
What is the pericellular/capsular matrix?
Dark outline around the lacune
It is the border between terretirial and interterritorial matrix
What is the territorial matrix?
Located within the lucunae
High in proteoglycans and ECM compotents
Dark apperence
What is the interterritorial matrix?
Between confrodytes
Low in proteoglycans
Light stain
What make the zones of matrix materials stain lighter or darker?
Increased proteoglycans = darker stain
Less proteoglycans = lighet stain
What is the hyaline histogenesis?
MSC -> developing cartilage (round and close) = chondrogenic blastema -> release matrix and begin distacning = chondroblasts -> trapped in lacunae with limited proliferation = isogenous gorups of chondrocytes
Appositional growth
formation of new carilage at surface of existing cartilage
Intersitial growth
formation of new cartilage within existing cartilage
What is matrix turnover?
The idea that there is continuous tissue remodeling thorughout life
If there is a loss of ECM or increase in forces, condrocytes replace and replinish the matrix
Talk me through endochondral ossification
- increae in blood vessels > increased O2 in the environment
- Perichondrim > periosteum > bone collor > makes osteocytes
- Limited diffusion of nutrients through cartilage > condrocytes reabsorb ECM > hyperdiated > condrocyte death
- Hallowing out of the primary ossification center > create marrow cavity > invasion of disaphysis = periosteal bud
- All happens again at secondary ossification center
What parts of the bone are the diaphysis, epiphysis, metaphysis, and periostium?
Diaphysis = long part, shaft
Epiphysis = ends
Metaphysis = between the two
Periostium = surrounds the bone (identical to perichondrium but with osteogenic cells that become osteocytes)
What are the five zones of the epiphysial plate?
- Zone of reserve cartilage
- Zone of porliferation - stacks of coins
- Zone of hypertrophy
- Zone of calcified cartilage
- Zone of reabsorption
What is the function of elastic cartilage? (2)
- Provides flexible, elastic support
- REsilience and pliability
Does elastic cartilage become calcified with age?
No
What is the function of fibrocartilage? (3)
- Shock absorption
- Resistance of compression and shearing forces
- Support and rigidity
Which cartilage is the strongest?
Fibrocartilage becasue of the type I colloagen
What are fibroblasts responsible for making in fibrocartilage? What about the chondrocytes?
Fibroblasts make type I colloagan
Chondrocytes make type II collagen and aggrecan
What happens when you have a herniated disc?
There is a ruprure in the anulus fibrosus that cuases the nuclus pulposes to spill out and pinch a nerve
What are the two layers of an intervertebral disc?
- Anulus fibrosous - external protective layer
- Nuclues pulpous - soft inner core; protien gel and loose fibers
Stress goes to nuclues pulpos adn then migrates out to anulus fibrosous
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Hyaline Cartilage
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Fibrocaritlage
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Elastic Cartilage
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Elastic Cartilage
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Hyaline Cartilage in fetal skeleton
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Hyaline Cartilage
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Perichondrial Fibroblast
Perichondrium
Chondroblast
Cartilage
Interteriirtorial Matrix
Chondrocyte
Territorial Matrix
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Haylaine Matrix
Type II collagen
Type IX collogen
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Perichondrium (fibrous layer)
Chrongenic layer
Isogenous groups
Territorial matrix
Interterritiorial matrix
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Neighboring DCT
P = perichondrium
chondrogenic layer
matrix
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Territorial Matrix, Interterritiroal matrix. periceullular/capsular matrix
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Isogenous groups
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Mesenchyme Cells
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Chondrogenic Blastema
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Chondroblasts and ECM
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Isogenous groups of chondrocytes
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Mesenchyme tissue
Developing Cartilage
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Endochonral Ossification
Upper panel (short bone, monkey)
- Hyaline cartilage model forms
- Cartilage cells become hypertrophic
- Matrix becomes calcified
- Periosteal bone forms around cartilage model
Lower panel (fetal finger, human)
Steps 1-4 à perivascular cells from periosteum have invaded the shaft of the cartilage model, resulting in formation of a cavity.
Within epiphysis, erosion of calcified cartilage occurs, creating spicules of cartilage where bone can form. (EB, endochondral bone)
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5 zones of the epiphysial plate
- Reserve Cartilage
- Proliferation - coins
- Hypertrophy
- Calcified Cartilage
- Reabsorption
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Elastic Cartilage
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Elastic Cartilage
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Elastic Cartilage
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Fibrocartilage
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Fibrocartilage
What three characteristics about cartilage limit its ability to repair?
- Avascular
- Chondrocyte immobility - can’t move to injury
- Limited replication of mature chondrocytes
What does injurty to cartilage stimulate?
Bone formation
What are the two phases of repairing a cartilage ingury as physician?
- Take cartilage from uninjured area and grow cells in vitro
- Implant; clean up the edges, patch over injuered area with periosteum and impoant cells under the patch
What three normal occurences cause hyaline cartilage to calficy? What does calcification decrease?
- Articular cartilage
- Endochondral ossification
- Aging process
Calcification decreases diffusion
What is osteoarthritis?
Decrease in cartilage > bone on bone > bone spurs, breakdown, inflammation
As you increase pressure > breakdown in hyaline cartilage (proteoglycans and GAGs in matrix) > lose hydration and cushion
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Calcification of cartilage
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Loss of cartilage as pressure increases