Extracellular Matrix Proteins Questions and Answers(A+ Solution guide)

Extracellular Matrix (ECM) - -relatively stable structural material that lies under epithelia & that surrounds connective tissue cells -can be divided into 2 structural components: fibers & amorphous ground substance Fibers - -an aggregate of fibrils -1-10 um diameter (largest) -can be divided into collagen & elastic -each is comprised of specific types of proteins -can assemble into bundles Fibrils - -an aggregate of filaments (filaments put together = fibrils) -20-500nm diameter -collagen fibrils usually < 100nm -can assemble info fibers Filament - -a threadlike structure -2-20nm in diameter -typically a single molecule or linear chain of molecules Ground Substance - -a complex of glycoproteins, glycoaminoglycans (GAG), proteoglycans -participates in binding cells to fibers of connective tissue -viscous transparent material -fills space btw cells & fibers in connective tissues Glycoprotein - -protein w/ one or more attached sugarsGlycosaminoglycan - -family of heteropolysaccharides -very hydrated -very negatively charged Proteoglycans - -comprised of a protein core with many glycosaminoglycan chains attached Basement Membrane - -"structureless" connective tissue immediately subjacent to basal surface of epithelia, kidney glomerulus, lung alveoli -several 100nm thick -sheet like structure that appears early in development Basal Lamina - -immediately adjacent to cell membrane -50-100nm thick -3-4nm filaments in amorphous matrix (ground substance) Reticular Lamina - -underneath basal lamina -usually contain fine collagen fibrils Connective Tissue (CT) - -high ratio of ECM to cells (high ratio of many things to the cell) -matrix serves structural function, provides architectural framework -composition of matrix (fibers & ground substance) Mineralized Tissues - -bone, enamel, dentin, cementum formed by mineralization of specialized ECMs Function of the ECM - -support or cells & cell layers -anchors cells to underlying stromal CT -Impedes the passage of cells -passive-selective molecular sieve btw tissue compartments-solid phase regulator of cell attachment, growth & differentiation -modulates the mineralization process Cell Types - -Fibroblasts: most connective tissues -Chondroblasts: cartilage -Osteoblasts: bone -Odontoblasts: dentin -Ameloblasts: enamel -Epithelia, Muscle fat, Schwann cells: basement membran