calcium homeostasis
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kidney. bone. calcium deposition. calcium resorption. 1000 g Ca++ stored in bone. Ca++ absorbed into blood. Ca++ lost in urine. Calcium in the diet. calcium lost in feces. small intestine. Calcium homeostasis. Blood Ca++. storage. kidney. calcium deposition. calcium resorption.

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Presentation Transcript
calcium homeostasis

kidney

bone

calcium deposition

calcium resorption

1000 g Ca++ stored in bone

Ca++ absorbed into blood

Ca++

lost in urine

Calcium in the diet

calcium lost in feces

small intestine

Calcium homeostasis

Blood

Ca++

slide2

storage

kidney

calcium deposition

calcium resorption

intake

Ca++ absorbed into blood

Ca++

lost in urine

excretion

Calcium in the diet

calcium lost in feces

small intestine

Calcium homeostasis

bone

Blood

Ca++

1000 g Ca++ stored in bone

calcium cycling in bone tissue
Calcium cycling in bone tissue
  • Bone formation
    • Osteoblasts
      • Synthesize a collagen matrix that holds Calcium Phospate in crystallized form
      • Once surrounded by bone, become osteocyte
  • Bone resorption
    • Osteoclasts
      • Change local pH, causing Ca++ and phosphate to dissolve from crystals into extracellular fluids
slide4

kidney

bone

calcium deposition

calcium resorption

Ca++ absorbed into blood

Ca++

lost in urine

Calcium in the diet

calcium lost in feces

small intestine

Calcium homeostasis

Blood

Ca++

hormonal regulators
Hormonal Regulators
  • Calcitonin (CT)
  • Parathormone (PTH)
  • 1,25 Vitamin D3
calcitonin ct
Calcitonin (CT)
  • Secreted from the C cells in the thyroid
  • Lowers Ca++ in blood
  • Promotes deposition of Ca++ into bone (inhibits osteoclasts)
  • Control of secretion from c-cells:

CT

hormonal regulators1
Hormonal Regulators
  • Calcitonin (CT)
    • Lowers Ca++ in the blood
    • Inhibits osteoclasts
  • Parathormone (PTH)
  • 1,25 Vitamin D3
parathormone pth
Parathormone (PTH)
  • Increases Ca++ in blood
  • Increases Ca++ resorption from the bone
    • Stimulates osteoclasts
    • Increases number of osteoclasts
  • Increases Ca++ resorption from nephron
  • Control of secretion:
  • Necessary for fine control of Ca++ plasma levels
hormonal regulators2
Hormonal Regulators
  • Calcitonin (CT)
    • Lowers Ca++ in the blood
    • Inhibits osteoclasts
  • Parathormone (PTH)
    • Increases Ca++ in the blood
    • Stimulates osteoclasts
  • 1,25 Vitamin D3
1 25 vitamin d3

UV

Cholesterol precursor

7-dehydrocholesterol

Vitamin D3

25 Vitamin D3

1,25 Vitamin D3

Low plasma Ca++ increase kidney enzymes

1,25 Vitamin D3
  • Increases Ca++ uptake from the gut
    • Increase transcription and translation of Ca++ transport proteins in gut epithelium
  • Minor roll: also stimulates osteoclasts
    • Increase Ca++ resorption from the bone
hormonal regulators3
Hormonal Regulators
  • Calcitonin (CT)
    • Lowers Ca++ in the blood
    • Inhibits osteoclasts
  • Parathormone (PTH)
    • Increases Ca++ in the blood
    • Stimulates osteoclasts
  • 1,25 Vitamin D3
    • Increases Ca++ in the blood
    • Increase Ca++ uptake from the gut
    • Stimulates osteoclasts
slide12

kidney

bone

1,25 Vit. D3 (+)

Parathormone (+)

PTH

Ca++

Ca++

1,25 Vit D3

Ca++

Ca++

small intestine

Calcium homeostasis

Blood

Ca++

Calcitonin (-)

resorption

deposition

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