BS 2 Flashcards
Articular hyaline cartilage:
How get nutrition
Top 3 components
Diffusion nutrition from synovial fluid
- Avascular (why doesn’t heal)
Components: H2O, PG, collagen (type 2 = car-two-lage)
Describe collagen structure
3 alpha collagen chains in a triple helix
Where do you find type X cartilage
Fracture callus
Hypertrophic zone growth plate
Calcified tidemark of articular cartilage
What are 2 genetic disorders that affect type 2 collagen of cartilage?
Achond - lethal kind
Spondyloepiphyseal dysplasia (SED-C) - congenita
- Mentally normal
- Proportional dwarfism (trunk + limbs)
What is the structure of PG
HA backbone
Protein core
Chondroitin + keratan sulfate
Overall negative charge molecule
Diastrophic dysplasia:
Inheritance
Mutated protein
Clinical presentation
AR
Sulfate transporter mutation - can’t get sulfate into cells to make PG (chondroitin and keratin sulfate)
Presentation
- Dwarfism
- Hitchhiker thumb
- Cauliflower ear
“If your sulfate transporter isn’t working, you have to hitchhike”
What is the only cell in cartilage? What TF controls it?
Chondrocytes - SOX9
What are the layers of cartilage from superficial to deep
Tangential - chondrocytes lay flat
- Most H2O + lubricin, least PG
Transitional/radial
Deep zone
Tidemark - contains Ca2+ cartilage (type X)
Subchondral bone
Cancellous bone
What are the 2 types of cells in synovium
Type A = mArcophAge like cells
- Removes debris from joint
- From bone marrow (hematopoietic)
Type B = fiBroBlast like cells
- Mesenchymal derived
- Make synovial fluid - lubricin, etc
What molecule is responsible for synovial fluid viscosity
Hyaluronic acid
Name molecules in synovial fluid
Hyaluronic acid
Lubricin
HA binds lubricin
Lubricin works via boundary lubrication
How does cartilage change with OA
Wet - increase H2O
Decrease modulus of elasticity (stress strain curve has lower slope)
How does cartilage change with aging
Less H2O - dry
Brittle = increased mod of elasticity
Increased decorin
What signaling molecules are upregulated in OA
IL 1beta
MMPs
ADAMTS
What is an antimicrobial peptide over expressed in psoriasis patients
Cathelicidins
Increased keratin in wound helaing