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

Aspects of the Bone ECM? - Answer-Organic and Inorganic What is found in the organic part of ECM? - Answer-Flexibility, Type I collagen and proteoglycan. There are also osteoectin, osteocalcin, and bone sialoprotein What do osteonectin, osteocalcin, and bone sialoprotein do respectively? What are they? - AnswerMembrane to matrix, Ca to matrix, and cells to matrix. Glycoproteins Inorganic part of ECM has what? What is special here? Where is the collagen in relation to special structure? - Answer-Minerals, strength part. Has hydroxyapatite crystals of CaPO4, these have hydration shells around them. Half of collagen is in them, half out Give the two types of bone which have type I collagen that is densely packed. How are the collagen arranged specifically? - Answer-Classified by arrangement of Collagen Woven Bone/Immature Bone/ Primary Bone Bundles of collagen in all directions Lamellar Bone/Secondary Bone/ Mature Bone Alternating layers of collagen fibers running in parallel. Can only be seen with polarized light Collagen layers called lamellae For the deposition of calcium, what are the two theories ? - Answer-Cellular Nucleation Theory and Macromolecular Nucleation Theory Describe the Cellular Nucleation Theory - Answer-This allows for calcification, so matrix vesicles pinch of the cytoplasm and contain alkaline phosphatase, which inhibits pyrophosphate, which in turn rases the CaPO4 levels Inhibitors of calcification have these 4 things - Answer-PPi, Nucleotides, citrates, or MgExplain the Macromolecular Nucleation theory, each of the 4 major players - Answer-Collagen fibers Gap between tropocollagens initiates calcification Half of hydroxyapatite is found here Osteocalcin Bone Glycoprotein Binds Ca to begin calc. Coumadin Interferes with carboxyl. of Glutamate Prevents osteocalcin syn. Used as anticoagulant Prevents Ca deposition Tracks osteoblastic activity Chondrocalcin Cartilage glycoprotein Binds Ca Sulfated proteoglycans Sequesters CaPO4 Explain the 2 classes of mineralization - Answer-Primary Mineralization First 3-4 days Majority of mineralization Controlled by osteoblasts and osteocytes Secondary Mineralization Several months long Examples of Long bone - Answer-HUmerus, femur, tibia, and fibula Examples of Short bones - Answer-Carpal and tarsalsExamples of irregular bones - Answer-Spine, hip, and face Example of flat bone - Answer-Skull, diploe (trabecular bone)