Connective Tissue Flashcards
(13 cards)
What is extracellular matrix?
Macromolecules secreted by cells - strength & hold cells together & in right position - regulate development, mitotic development & survival of cells - protein fibres & ground substance
What is ground substance?
Colourless viscous gel-like fluid between cells - delays spread of infection
What are 3 components of ground substance?
Glycosaminoglycans (GAGs), Proteoglycans, Cell-Adhesive Glycoproteins
What are glycosaminoglycans?
Long negatively charged polysaccharides containing glucosamine - unbranched - charge attracts sodium ions which in turn attracts fluid - resist each other (“slippery”) - covalently linked to protein to form proteoglycans - most are sulphated (Keratin sulphate, heparin sulphate, dermatin sulphate, chondroitin-4-sulphate, condroitin-6-sulphate) - non-sulphated = hyaluronic acid
What are proteoglycans?
GAGs covalently bonded to protein - make ECM firmer - binds to water (gelatinous texture) - facilitate normal cell movement - molecular filter with basal lamina
What are cell-adhesive glycoproteins?
Adhere cells to cells & surroundings - binds to integrins (cell surface proteins), protein fibres (collagen) & proteoglycans - fibronectin, laminin, intactin, teanascins, chondronectin, osteonectin
How many fibre types are there?
2 - collagen & elastin (reticular fibres are now known to be a form of collagen)
What is the most abundant protein in the body?
Collagen - 20-25%
How many types of collagen is there?
35 - various morphology & amino acid sequences
What can types of collagen be subdivided into?
Fibre forming, mesh/network forming, & cell membrane associated proteins
What is the main function of collagen?
Provides tensile strength
Where is collagen made?
Fibroblasts in connective tissue secrete tropocollagen monomers ( 3 alpha polypeptide chains - 300nm long, 1.5nm in diameter) - polymerise to form collagen fibrils - cross linked by lysl oxidase
