A brief about Bone

 Bone 

        A dynamic form of specialized connective tissue. Cells - 10 % ; Extracellular matrix (ECM)- 90 %.

        Cells - 1. Osteoblasts , Osteocytes, Osteoclasts

        ECM  -- 1. Organic - type I collagen 

                       2. Inorganic - Calcium Phosphate, Osteocalcium Phosphate.




 Functions

       1. movement

        2. support and protect internal organs

        3. produces RBCs/ WBCs

        4. storage for calcium and phosphte 

  Difference 

        Osteoblasts 

                    - derived from undifferentiated mesenchymal cells

                    - bone forming ,lay down Osteoid (type I collagen)

                    - contains RANK (receptor activator for nuclear factor kappa 

                   

          Osteoclasts 

                    - monocyte lineage multinucleated giant cells that resorb bone

                    - location - small pits called Lacunae,bone surfaces and lead cutting cones.

                    - ruffled brush border ,increase surface area ,create low ph to dissolve inorganic                                          compounds

                    - Enzymes release - Tartarate resistant acid phosphatase and proteases 

                    - breaks down organic matrix components

                    - inhibits Osteoprotegrin.

            Osteocytes

                    - Osteocytes that have become trapped in bone matrix 

                    - 90 % of cells in bone, important role in homeostasis of Ca and Phosphate

                    

Wolff's Law 

                German Anatomist/Surgeon Jullius Wolff . 

                If loading on bone increases , bone remodel itself over time to become stronger to resist load.



        


   

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