Cartilage Bone Development Flashcards

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1
Q

What is the structural function of cartilage and matrix

A

Keeps us upright

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2
Q

What 3 types of cartilage are there , give examples

A

Hyaline - articular joints,ribs,trachea

Fibro - ligaments

Elastic - ear, larynx

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3
Q

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

A

Hyaluronic acid

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4
Q

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

A

Chondrocytes spaced far apart

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5
Q

Bone develops from cartilage. What is cartilage

A

A precursor

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6
Q

What would happens in articular joints if no cartilage ecm

A

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

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7
Q

Which 2 components are major in cartilage ecm

A

Collagen type II

Aggrecan

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8
Q

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

A

Ehlers danlos syndrome eg col1a1 mutation

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9
Q

What allows hydration of ecm and why important

A

Sulphated aggrecan attracts na charges and causes osmosis into the ecm

Allows withstand of compression
Produces swelling pressure (turgor)

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10
Q

Which type of organelles are chondrocytes rich of and why

A

Rer and Golgi

Production of aggrecan and col II

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11
Q

What 3 types of chondrocytes are there and why

A

A vascular (withstand hypoxia)

Alymphatic (no lymphs in ecm)

Aneuronal (no neurones)

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12
Q

Which stem cells produce chondrocytes to produce cartilage

A

Mesenchymal sc

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13
Q

What other cells do msc make

A

Bone, adipose cells, muscle cells ,

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14
Q

What does msc express which turns on chondrocytes pathway

A

Sox 9 (hmg box dna binding tf)

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15
Q

What does sox9 turn on

A

Col2a for collagen 2 production and pathway for chondrocytes

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16
Q

What allows chondrocytes proliferation once pathway turned on from msc

A

Tgf b , igf 1, fgf, pthrp

17
Q

What is pthrp

A

Parathyroid hormone related protein

Specific to chondrocytes

18
Q

What is cartilage development during embryogenesis called

A

Cartilage model

19
Q

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

A

Spatial development (happens in ossification)

20
Q

What is bone formation from cartilage called

A

Endochondral ossification

21
Q

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

A

In primary ossification centre

22
Q

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

A

Inductive signalling

Eg explains why chondrocytes start moving outwards

23
Q

Which morphogen causes chondrocyte spatial proliferation/ hypertrophy via pthrp

A

Hedgehog IHH, shh,dhh

24
Q

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

A

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

25
Q

What gets internalised and degraded when ihh binds to i hog

A

Patched- inhibitor of smoothered which usually sits on membrane

26
Q

Now that patched is degraded what happens

A

Smoothened moves to membrane

Causes blocking of proteolytic processing of cubitis interruptus

Can’t become a repressor

Instead is a conactivetor

27
Q

What does hedgehog cause the co activation of

A

Pthrp

28
Q

What type of receptor does pthrp bind

A

Gcpr

29
Q

Which tf needed for pthrp action

A

Sox9 from msc

30
Q

How is pthrp in a positive loop

A

Turns itself on and also the exp of more IHH

31
Q

What occurs in pthrp action

A

Chondrocyte proliferation and lack of terminal differentiation into osteoblasts

32
Q

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

A

Osteoid ecm from osteoblasts

Hydroxyapatite and collagen binds calcium and it gets calcified

Blocks osteoblast release

33
Q

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

A

The morphogen inductive signalling outwards for spatial development

34
Q

What produces more osteoblasts during endochondral ossification

A

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

35
Q

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

A

More diff, less proliferation, more death into bone