Download MBBS Physiology Presentations 13 Hormonal Control of Calcium And Phosphate Metabolism Lecture Notes

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metabolism

Introduction

Calcium is an intracellular signaling

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molecule

1100 gms of calcium is present in the

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body

99% is in the skeleton
Plasma calcium = 10 mg/dl; is partly

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bound to proteins and partly diffusible

Phosphorus

Found in AT P, c AMP, 2,3-BPG,

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proteins

Total body phosphorus ? 500-800 gm
85-90 % is in the bones

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Plasma phosphorus ? 12 mg/dl
2/3 of it is organic form and rest in

inorganic form- phosphate, hydrogen

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phosphate and dihydrogen phosphate
Vitamin D

Increases calcium absorption from the

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intestine

Increases phosphate absorption

through intestine

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Decreases renal excretion of calcium

and phosphate
1,25- dihydroxycholecalciferol is also

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formed in placenta, keratinocytes in

skin and macrophages

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Levels are increased in pregnancy

Parathyroid hormone

Increases calcium and phosphate

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absorption from the intestine

Increases calcium and phosphate

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absorption from bones

Decreases renal excretion of calcium

and increases renal phosphate

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excretion
Calcitonin

It is proportional to plasma calcium

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levels

-adrenergic agonists, dopamine and

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estrogens stimulate calcitonin

secretion

Gastrin, CCK, glucagon and secretin

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also stimulate

Plasma calcitonin levels are high in

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Zollinger-Ellison syndrome and

pernicious anemia

Calcitonin lowers plasma calcium and

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phosphate levels

Inhibits bone resorption
Vitamin D Deficiency diseases

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Rickets
osteomalacia

Osteopetrosis:

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Increased bone density

Osteoporosis:
Decreased bone density
Fractures common

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