Extracellular Matrix Flashcards
What is the extracellular matrix made up of?
Connective tissue - fibres, fibroblasts and ground substance.
What is collagen?
A fibrous, rope-like molecule that provides tensile strength to all tissues in the body.
Example of collagen l distribution
In skin, tendons, ligaments, cornea, internal organs
Example of collagen ll distribution
Cartilage, notochord
What is the structure of collagen?
A long, stiff triple helix structure where 3 collagen molecules twist around each other to form a superhelix. Triple helices combine to form collagen fibrils, and then fork collagen fibres.
How are collagens covalently cross linked?
Via lysyl hydroxylase and prolyl hydroxylase. Both require iron and vitamin C.
Which cell produces collagen normally/in bone?
Normally - fibroblasts.
In bone - osteoblasts.
Which cell is involved in scar formation?
Fibroblasts
What is the precursor of collagen?
Procollagen.
Why is collagen made as a precursor first?
Produced as procollagen inside the cell, which has additional peptides so will not be assembled into fibrils inside the cell. Only extracellular enzymes (procollagen proteinases) can cut off these peptides to allow assembly of collagen fibres.
What is Ehlers-Darlos syndrome?
Mutation of procollagen proteinases, so collagen fibres don’t assembly properly in skin and other tissues.
How can cells degrade the extracellular matrix?
Matrix metalloproteinases degrade ECM so macrophages can invade tissue during infection.
How do cells attach to the ECM?
As cells attach poorly to bare collagen, they attach to fibronectin instead via transmembrane receptors called integrins. Integrins attach to actin cytoskeleton to give tensile strength.
How does the ECM resist compression?
Using glycosaminoglycans, which resist compression and fill space
What do glycosaminoglycans form?
They form gels that make up the ground substance
