Cartilage Bone Development

Question 1

What is the structural function of cartilage and matrix

Answer 1

Keeps us upright

Question 2

What 3 types of cartilage are there , give examples

Answer 2

Hyaline - articular joints,ribs,trachea

Fibro - ligaments

Elastic - ear, larynx

Question 3

What is the main component of hyaline cartilage like ribs and articular joints

Answer 3

Hyaluronic acid

Question 4

In between bones like tibia and femur in knee is cartilage, what cells are there

Answer 4

Chondrocytes spaced far apart

Question 5

Bone develops from cartilage. What is cartilage

Answer 5

A precursor

Question 6

What would happens in articular joints if no cartilage ecm

Answer 6

Joint movement would be painful or they would lock eg in arthritis

Question 7

Which 2 components are major in cartilage ecm

Answer 7

Collagen type II

Aggrecan

Question 8

Which syndrome is caused by lack of collagen which causes hyper extensive joints

Answer 8

Ehlers danlos syndrome eg col1a1 mutation

Question 9

What allows hydration of ecm and why important

Answer 9

Sulphated aggrecan attracts na charges and causes osmosis into the ecm

Allows withstand of compression
Produces swelling pressure (turgor)

Question 10

Which type of organelles are chondrocytes rich of and why

Answer 10

Rer and Golgi

Production of aggrecan and col II

Question 11

What 3 types of chondrocytes are there and why

Answer 11

A vascular (withstand hypoxia)

Alymphatic (no lymphs in ecm)

Aneuronal (no neurones)

Question 12

Which stem cells produce chondrocytes to produce cartilage

Answer 12

Mesenchymal sc

Question 13

What other cells do msc make

Answer 13

Bone, adipose cells, muscle cells ,

Question 14

What does msc express which turns on chondrocytes pathway

Answer 14

Sox 9 (hmg box dna binding tf)

Question 15

What does sox9 turn on

Answer 15

Col2a for collagen 2 production and pathway for chondrocytes

Question 16

What allows chondrocytes proliferation once pathway turned on from msc

Answer 16

Tgf b , igf 1, fgf, pthrp

Question 17

What is pthrp

Answer 17

Parathyroid hormone related protein

Specific to chondrocytes

Question 18

What is cartilage development during embryogenesis called

Answer 18

Cartilage model

Question 19

What is the term called which cells receive signal based on what location they’re in eg for proliferation

Answer 19

Spatial development (happens in ossification)

Question 20

What is bone formation from cartilage called

Answer 20

Endochondral ossification

Question 21

Where do osteoblasts either derived from msc or hypertrophic chondrocytes stay/ get trapped

Answer 21

In primary ossification centre

Question 22

What is the process of signalling to cells in spatial development through morphogens called

Answer 22

Inductive signalling

Eg explains why chondrocytes start moving outwards

Question 23

Which morphogen causes chondrocyte spatial proliferation/ hypertrophy via pthrp

Answer 23

Hedgehog IHH, shh,dhh

Question 24

What happens which causes co repression if hedgehog isn’t present

Answer 24

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

Question 25

What gets internalised and degraded when ihh binds to i hog

Answer 25

Patched- inhibitor of smoothered which usually sits on membrane

Question 26

Now that patched is degraded what happens

Answer 26

Smoothened moves to membrane Causes blocking of proteolytic processing of cubitis interruptus Can’t become a repressor Instead is a conactivetor

Question 27

What does hedgehog cause the co activation of

Answer 27

Pthrp

Question 28

What type of receptor does pthrp bind

Answer 28

Gcpr

Question 29

Which tf needed for pthrp action

Answer 29

Sox9 from msc

Question 30

How is pthrp in a positive loop

Answer 30

Turns itself on and also the exp of more IHH

Question 31

What occurs in pthrp action

Answer 31

Chondrocyte proliferation and lack of terminal differentiation into osteoblasts

Question 32

What type of ecm is in the primary ossification centre and why important

Answer 32

Osteoid ecm from osteoblasts Hydroxyapatite and collagen binds calcium and it gets calcified Blocks osteoblast release

Question 33

What does spread of chondrocytes to ends of bone get made by

Answer 33

The morphogen inductive signalling outwards for spatial development

Question 34

What produces more osteoblasts during endochondral ossification

Answer 34

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

Question 35

What are the characteristics of the cells in middle of long bone

Answer 35

More diff, less proliferation, more death into bone