Connective tissue Flashcards
How is collagen made?
Pro-collagen –> tropocollagen –> collagen fibrils –> collagen fibres
What makes collagen and elastic?
Fibroblasts
What is tropocollagen?
- A single collagen molecule
- Triple helix
What forms cartilage?
Aggrecan aggregates
What is pro-collagen?
Precursor of collagen
What is needed for collagen synthesis?
Vitamin C
What are the 4 types of GAG?
1) Hyaluronic acid
2) Dermatan sulphate
3) Heparan sulphate
4) Kerartin sulphate
What are the functions of connective tissue?
Storage Support Repair Transport Protection
What are GAGs?
- Glycosaminoglycans
- Main substance in the matrix of connective tissue
- Spacefilling
- Unbranched polysaccharides
- Made of disaccharide repeate units
How do GAGs allow cushioning?
- Have a negative charge due to n-acetylglucosamine
- Retain positive ions (Na+)
- Osmotically active
- Swell as water moves in
- Turgid
Where is connective tissue derived from?
Mesoderm
What are the features of elastic?
- White
- Branched
- Thin
- Stretch and recoil
What are the features of collagen?
- Yellow
- Unbranched
- Thick
- Strength and support
What is collagen rich in?
- Glycine
- Proline
- Hydroxyproline
What are fibrocytes?
- Inactive fibroblasts
- Called tendinocytes in the tendons
- Don’t produce fibres
What are proteoglycans?
- At least one side chain is a GAG
- GAG covalently bonded to serine in a core protein via a tetrasaccharide linkage unit
What are aggrecan aggregates?
- Many proteoglycans (aggrecan) attached to a hyluronan chain
How do GAGs allow signal biding and filtering?
- Have a negative charge due to n-acetylglucosamine
- Capture and immobilise positive molecules (esp. Na+ )
- Keep in place long enough for receptors to bind
What is the different between brown fat and white fat?
Brown fat
- Common in childhood
- Lots of fat vesicles
- Burn fat to produce heat
- Lots of mitochondria
White fat
- Fat vesicles have formed fat droplets
- Has receptors for insulin, growth hormone, thyroid
- Good blood and nervous system
What are the disaccharide repeat units of GAG polysaccharides?
Amino sugar and uronic acid
What is the structure of collagen?
- 2 types of short segment repeated
- Hydrophobic protein
- Bound with fibrillin
- Interwoven with inelastic collagen fibres to limit stretches
Where is type VII collagen found?
- Anchoring fibrils in the basement membrane
Where is type IV collagen found?
- In the basal lamina
- Forms sheets
What type of collagen is the most common?
Type 1
- Large, branched fibres
- Skin, tendons and bone
Why do fibroblasts have lots of RER?
Active, produces fibres
Euchromatic nucleus
Where are proteoglycans formed?
In the golgi
What enzyme breaks down aggregates?
Hyluronidase
