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Hormones Involved In Bone By Yapa Wijeratne
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Hormones Involved In Bone By Yapa Wijeratne

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This presentation explains how the number of hormones are involve in bone metabolism in human body.

This presentation explains how the number of hormones are involve in bone metabolism in human body.

Published in: Health & Medicine

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    • 1. Hormones involved in bone metabolism
      by Yapa Wijeratne
      Faculty of Medicine
      University of Peradeniya
      Sri Lanka
    • 2. PTH
      Calcitriol
      Calcitonin
      Oestrogen
      Cortisol ( glucocorticoids)
      Thyroid hormones
      Insulin
      GH
      IGF
    • 3. 1.PTH
      Secreted by Chief cells of the parathyroid gland
      84 amino acid(AA)
      ↓ [Ca+2]ECF (+) secretion
      ↑ [PO4-3]serum
      PTH active PTH(amino terminal fragment)
      1-841-34
      carboxy terminal fragment
      35-84
    • 4. PTH
      Act directly on bones –
      ↑osteoclast (OC) activity to ↑bone resorption -> ↑mobilize [Ca+2] -> ↑[Ca+2]serum
      ↓Reabsorption of [PO4-3]in PCT
      ↑Reabsorption of [Ca+2] in DCT
      ↑ formation of 1,25 DHCC & this ↑ [Ca+2] absorption from the intestine.
    • 5. 2.Calcitriol
      ↑Transcription of calbinding D protein in the intestine.
      ↑Intestinal Ca+2 absorption by facilitating Ca+2 transport.
      Facilitates Ca+2 reabsorption in the kidney.
      ↑The synthetic activity of osteoblast (OB) & is necessary for normal calcification of matrix
    • 6. 3.Calcitonin
      By Parafollicular cells of thyroid gland.
      32 AA
      Secretion is regulated by serum[Ca+2].
      Inhibit OC bone resorption
      ↑Ca+2 Excretion in the urine
    • 7. 4.Estrogen
      ↑OB functions
      ↓OC functions
      ↓Renal excretion of Ca+2 & PO4-3
      ↓intestinal excretion of Ca+2 & PTH function
    • 8. 5. Cortisol ( glucocorticoids)
      lower plasma Ca2+ levels by inhibiting osteoclast formation and activity.
      Over long periods they cause osteoporosis by ↓bone formation & ↑bone resorption.
      ↓bone formation by inhibiting protein synthesis in OB.
      ↓Absorption of Ca+2 & PO4-3 from the intestine
      ↑Renal excretion of Ca+2 & PO4-3
    • 9. 6. Thyroid hormones
      Promote normal growth and skeletal development.
      May cause hypercalcemia, hypercalciuria, and, in some instances, osteoporosis.
    • 10. 7. Insulin
      ↑Bone formation (via OB activity)
      DM -> ↓insulin -> Significant bone loss in untreated DM.
    • 11. 8.GH
      Anabolic effect on bone
      Promotes the growth of the skeleton
      These effects in are believed to be mediated by IGF I & II acting on cells of the OB.
      ↑urinary excretion of Ca+2 & hydroxyproline
      ↑Intestinal absorption of Ca+2
      NET EFFECT (+) Ca+2 balance
      ↓urinary excretion of PO4-3
    • 12. 9.IGF -I
      Long arm of chromosome 12 & produces a 70 AA polypeptide.
      Receptor (®) IGF-I = insulin
      ® -> stimulates Tyr kinase activity & autophosporylation of the Tyr residue in ® -> cell differentiation & division
    • 13. IGF-I
      Stimulate Growth without GH
      Stimulate Protein synthesis in bone
      Has stimulatory effect on
      Hematopoiesis
      Ovarian steroidogenesis
      Myoblast proliferation
      Differentiation of lens
    • 14. IGF-II
      67 AA peptide
      Short arm of chromosome 11
      [IGF II]plasma vary with
      Age
      Physiological condition (peak during puberty)
      Neonates children puberty adult
    • 15. IGF-BPS
      IGF molecules in the circulation are mostly bound to variety.
      IGF-BPS I (-) action of IGF I
      It is present in ↑ [ ] in fetal serum & amniotic fluid.