Bone tissue composition - ECM Flashcards
What is the ECM of bones?
Structural and biochemical substrate of cells
What cellular processes happen within the ECM?
Adhesion
Communication
Differentiation
What are the two main components of ECM?
Organic component - proteinaceous
Inorganic component - bone mineral
Definition of proteinaceous
Of, relating to, resembling or being protein
What percentage of dry weight do the organic components of the ECM make up?
35%
What is the main structural protein in the organic components of the ECM?
Collagen type I
What are associated bone matrix proteins of the organic components of the ECM?
Osteocalcin
Osteonectin
Osteopontin
Bone sialoprotein
Fibronectin
What is the role of the organic component of the ECM?
Resist tensile forces
Via formation of structures
Fibrils of different diameters are organised in different ways in different tissues
How is the skin organic matrix adapted to its function?
Fibers are woven in a wickerwork pattern
Resist tensile stress in multiple directions
How is the organic matrix of tendons adapted to their function?
Collagen fibrils are organised in parallel bundles
Alignes along the major axis of collagen type I
What is the major component of inorganic matrix?
Hydroxyapaptite
Ca10(PO4)6(OH)2
What is the role of the inorganic matrix?
Main mediator of compressive strength
What percentage of the dry weight does the inorganic matrix comprise?
70%
What cells synthesise the inorganic matrix?
Osteoblasts
Secretes phosphate and calcium ions
These precipitate onto collagen as hydroxyapaptite ions in controlled environment at critical concentration
What are nucleation core complexes?
Matrix vesicles that are secreted and contain ALP
Provide isolated environments where mineralisation is initiated
Localised increases of calcium though active transport and phosphate initiate mineralisation
