Cartilage Bone Development Flashcards
What is the structural function of cartilage and matrix
Keeps us upright
What 3 types of cartilage are there , give examples
Hyaline - articular joints,ribs,trachea
Fibro - ligaments
Elastic - ear, larynx
What is the main component of hyaline cartilage like ribs and articular joints
Hyaluronic acid
In between bones like tibia and femur in knee is cartilage, what cells are there
Chondrocytes spaced far apart
Bone develops from cartilage. What is cartilage
A precursor
What would happens in articular joints if no cartilage ecm
Joint movement would be painful or they would lock eg in arthritis
Which 2 components are major in cartilage ecm
Collagen type II
Aggrecan
Which syndrome is caused by lack of collagen which causes hyper extensive joints
Ehlers danlos syndrome eg col1a1 mutation
What allows hydration of ecm and why important
Sulphated aggrecan attracts na charges and causes osmosis into the ecm
Allows withstand of compression
Produces swelling pressure (turgor)
Which type of organelles are chondrocytes rich of and why
Rer and Golgi
Production of aggrecan and col II
What 3 types of chondrocytes are there and why
A vascular (withstand hypoxia)
Alymphatic (no lymphs in ecm)
Aneuronal (no neurones)
Which stem cells produce chondrocytes to produce cartilage
Mesenchymal sc
What other cells do msc make
Bone, adipose cells, muscle cells ,
What does msc express which turns on chondrocytes pathway
Sox 9 (hmg box dna binding tf)
What does sox9 turn on
Col2a for collagen 2 production and pathway for chondrocytes
What allows chondrocytes proliferation once pathway turned on from msc
Tgf b , igf 1, fgf, pthrp
What is pthrp
Parathyroid hormone related protein
Specific to chondrocytes
What is cartilage development during embryogenesis called
Cartilage model
What is the term called which cells receive signal based on what location they’re in eg for proliferation
Spatial development (happens in ossification)
What is bone formation from cartilage called
Endochondral ossification
Where do osteoblasts either derived from msc or hypertrophic chondrocytes stay/ get trapped
In primary ossification centre
What is the process of signalling to cells in spatial development through morphogens called
Inductive signalling
Eg explains why chondrocytes start moving outwards
Which morphogen causes chondrocyte spatial proliferation/ hypertrophy via pthrp
Hedgehog IHH, shh,dhh
What happens which causes co repression if hedgehog isn’t present
Patched protein stays active and inhibits smoothened
This means the proteolytic processing of cubitis interruptus tf isn’t affected
After it’s proteolytic processing ci can go to nucleus and co repress genes for chondrocytes spatial proliferation
What gets internalised and degraded when ihh binds to i hog
Patched- inhibitor of smoothered which usually sits on membrane
Now that patched is degraded what happens
Smoothened moves to membrane
Causes blocking of proteolytic processing of cubitis interruptus
Can’t become a repressor
Instead is a conactivetor
What does hedgehog cause the co activation of
Pthrp
What type of receptor does pthrp bind
Gcpr
Which tf needed for pthrp action
Sox9 from msc
How is pthrp in a positive loop
Turns itself on and also the exp of more IHH
What occurs in pthrp action
Chondrocyte proliferation and lack of terminal differentiation into osteoblasts
What type of ecm is in the primary ossification centre and why important
Osteoid ecm from osteoblasts
Hydroxyapatite and collagen binds calcium and it gets calcified
Blocks osteoblast release
What does spread of chondrocytes to ends of bone get made by
The morphogen inductive signalling outwards for spatial development
What produces more osteoblasts during endochondral ossification
The movement of proliferating c outwards via pthrp and ihh, cells in centre get less of these
Less pthrp means more terminal differentiation into osteoblasts
What are the characteristics of the cells in middle of long bone
More diff, less proliferation, more death into bone
