Lecture 18-endo 5 - Increases calcium reabsorption at the...

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The Endocrine System Dr. K. Banks V. Hormones of Calcium Balance Lecture 18 1 III. The Thyroid V. Hormones of Calcium Balance VII & VIII. Hormonal Regulation of Reproduction IV. The Adrenal Glands VI. Hormonal Regulation of Energy Metabolism 2 Calcium Regulation Three hormones control Ca 2+ levels Three target sites for control of Ca 2+ levels 3 Fig 6.8b Functions of Calcium Important component of bone and teeth Exocytosis of chemical messengers Stimulates muscle contraction Increases contractility of heart and blood vessels Essential for normal blood clotting 4
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99% of body calcium is in bone, stored as hydroxyapatite = Ca 10 (PO 4 )(OH) 2 Bone also contains cells: Osteoblasts: bone deposition Ca 2+ added to bone when [Ca 2+ ] high Osteoclasts: bone resorption Ca 2+ liberated from bone when [Ca 2+ ] low Body Reservoir of Calcium: Bone 5 PTH Actions Stimulates bone resorption
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Unformatted text preview: Increases calcium reabsorption at the kidneys Activates calcitriol to indirectly increase calcium levels (Direct action to increase absorption at digestive tract) 6 7 Fig. 19.21 Calcitriol Actions Increases calcium absorption at the digestive tract Increases calcium reabsorption at the kidneys 8 9 Fig. 19.22 Calcitonin Actions Stimulates bone deposition Increases excretion of calcium at the kidneys 10 Thyroid Gland Histology 11 Fig. 21.13a Reabsorption 1,25-(OH 2 )D3 stimulates ? 12 Fig. 19.20 Osteoporosis Decreased bone mass leading to bone fragility and increased fracture risk Risk factors: Post menopausal (estrogen deficiency) Lack of exercise (esp. weight bearing) Calcium, vitamin D deficient diet Current cigarette smoking 13 Bone Density Testing 14...
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This note was uploaded on 04/04/2011 for the course PSL 201 taught by Professor Wojtowicz during the Winter '08 term at University of Toronto- Toronto.

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Lecture 18-endo 5 - Increases calcium reabsorption at the...

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