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Basic Science

Basic bone Structure


Functions of bones are:

  1. Support
  2. Protect (vital organs)
  3. Leverage
  4. Reservoir of minerals (Calcium)
  5. Hematopoietic

Mature bone devided in to cortical and cancellous


Basic structural unit of bone is osteon (shown below).


Organic (40%) Inorganic (60%)
Collagin type I Calcium hydroxyapetite
Proteio glygen Osteo calcium phosphate
Non collagen matrix protein
  1. Osteo calcium
Growth factor
  1. BMP
  2. TGFb
  3. IGF
  4. PDGF
  1. Osteoblast
  2. Osteocytes
  3. Osteoclast


Table: Regulation of calcium and phosphate metabolism




Kidney: conversion of vit D, Bone: resorption, Net(Ca ↑, PO4↓)


Intestine ↑ absorption, Kidney x, Bone resorption, Net (Ca↑, PO4↑)

Calcitonin: Bone resorption inhibition, Net (Ca ↓)


Other Bone Regulators
  1. Magnasium: Efficient secreation and action of PTH.
  2. Estogen: Via RANK / RANK L / OPG system
  3. Androgen: Retards bone resoption
  4. Thyrixoine: Increased bone turnover (Osteoprosis)
  5. Temprature / oxigen tension: Increases bone formation
  6. Acidity: Increases bone resorption
  7. Fluride: Increases osteoblastic activity (without increasing tensile strength)
  8. Pyrophosphate: Inhibits bone resobption.
  9. Growth hormone: Positive calcium balance
  10. Corticosteroids: Increases bone loss
Marker of bone formation:
  1. Osteocalcium (Urine / Serum)
  2. Alkaline phosphotase
Marker of bone resorption
  1. Hydroproline
  2. Pyridinium
  3. Telopeptide
  4. Serum TRAP (Tatrate resistent acid phosphatase)

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