Difference between revisions of "Bone Response to Damage"

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**Regulated by androgens
 
**Regulated by androgens
 
*If growth teporarily stops -> layer of bone seals the growth plate -> moves into metaphysis when growth resumes -> forms '''Harris lines'''
 
*If growth teporarily stops -> layer of bone seals the growth plate -> moves into metaphysis when growth resumes -> forms '''Harris lines'''
 
===Bone resorption===
 
 
*Mediated by two [[Parathyroid Pathology#Hormonal Control|hormones]]:
 
**'''Parathyroid hormone (PTH)'''
 
***Produced by <u>chief cells in the parathyroid glands</u> in response to <u>decreased</u> serum calcium
 
***In response, osteoclasts increase in number and resorb mineralised matrix - increase Ca in blood
 
**'''Calcitonin'''
 
***Produced by <u>C-cells in the thyroid glands</u> in response to <u>increased</u> serum calcium
 
***Inhibits osteoclasts
 

Revision as of 10:34, 18 July 2008

BACK TO BONES



Normal structure

    • Damage to periosteum:
      • Invokes a hyperplastic reaction of the inner layer
      • Is painful
      • Exostoses can remodel or remain
    • Lifting of periosteum causes new bone formation below
    • Circumferential incision (e.g. during fracture)
      • Longitudinal bone growth results
      • May be only on one side where periosteum is damaged


Physis (Growth plate)

  • Site of many congenital or nutritional bone diseases in the growing animal
  • Open in neonates and growing animals
    • Chondrocyte proliferation balances cell maturation and death
  • Closes and ossifies at maturity
    • Regulated by androgens
  • If growth teporarily stops -> layer of bone seals the growth plate -> moves into metaphysis when growth resumes -> forms Harris lines