ECM

ECM

Part of tissue that:
1. Sequesters water – turgor for soft tissue
2. Sequesters minerals – rigidity for bone
3. Substrate for cell adhesion
4. Reservoir for growth factors – reg proliferation, movement, differentiation of cells within it
Tissue repair depends on growth factor activity and interaction between cells and ECM components
Interstitial matrix
1. Spaces between cells in CT, between EP – Between EP and supportive vascular and SM tissue
2. Forms 3D amorphous gel
3. Constituents
  1. Collagen (fibrilar/non-fibrilar
  2. Fibronectin
  3. Elastin
  4. Hyaluronan
Basement membrane
1. CT between EN and everything else below it
2. Highly organised around EP and EN = specialised BM
3. Synthesized by EP (above) and mesenchymal cells (below)
4. Constituents
  1. Collagen (non-fibrilar)
  2. Laminin
  3. Proteoglycan
Role
1. 1. Mechanical support – cell adhesion, migration
2. 2. Control cell growth – components regulate proliferation
3. 3. Maintain cell differentiation – ECM proteins affect degree of differentiation
4. 4. Scaffolding for tissue renewal – integrity of BM critical for organised tissue regeneration
5. IF ECM damaged > collagen deposition and scar formation
Components
1. Fibrous structural proteins
  1. Strength and recoil
  2. Collagen – Fibrilar (cross-linking giving tensile strength), Non-fibrilar (BM, IV discs)
  3. Elastin – recoil and return to base structure after stress (BV, uterus, skin, ligaments)
2. Water hydrated cells
  1. Turgor > resilience and lubrication
  2. Proteoglycans – hydrated compressible cells give resilience and lubrication (cartilage and joints)
  3. Hyaluronan – Able to bind water forming viscous gel-like matrix adding to compresability of tissue (reservoir for GF)
3. Adhesive glycoproteins
  1. Adhesion between Cell-Cell, Cell-ECM, ECM-Components
  2. Fibronectin – Binds to many ECM components, Tissue (aggregates at wound sites), Plasma (binds to fibrin during clot formation and for re-EP)
  3. Laminin – Cell to underlying components mediating attachment to BM
  4. Integrins – transmembrane glycoproteins, main receptors for ECM components connecting intra and extracellular environemnts
GENETIC DEFECTS
1. Osteogenesis imperfecta
  1. Collagen defect – Brittle bone disease
  2. Defective collagen gene leading to formation of abnormally fragile bones
  3. Defects in eyes d/t insufficient deposits (blue sclera)
  4. Lax ligaments – dislocations
  5. Teeth - weak and brittle
  6. Otosclerosis – tympanic membrane and earbones become hard and fused
2. Ehlers-Danlos syndrome
  1. Skin – very elastic with retraction, but not enough colagen to give strenth, vulnerable to trauma
  2. Genetic disorder affecting collagen in CT
  3. Joints – hypermobile, dislocate easily
  4. Corneal detachment – not enough collagen in cornea
  5. Diaphragmatic hernia
  6. Rupture of large arteries (aorta, femoral, carotid) and colon
3. Marfan syndrome
  1. Genetic defect of fibrillin resulting in structural loss of CT
  2. Tall growth with arachnodactily
  3. Indented breastbone (affects respiration/heart)
  4. Aorta – prolapsed valves, dissection, aneurism

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	Created by Lindie Metz about 8 years ago