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19 Cards in this Set
- Front
- Back
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What 2 things are regulated by Vit D?
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1. Gene transcription
2. Ca2+/Phosphorus metabolism |
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What are the 2 dietary forms of Vitamin D?
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1. Cholecalciferol (D3)
2. Ergocalciferol (D2) |
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What does the body use to synthesize Vitamin D?
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7-dehydrocholesterol
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What converts 7-dehydrocholesterol to cholecalciferol?
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UV light in skin
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Where does Cholecalciferol go after conversion from cholesterol?
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To the liver
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What happens to Vit D in the liver?
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Conversion to active form
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What is the active form of Vit D?
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1,25-dihydroxy vitamin D
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Where exactly does the activation of Vit D occur?
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Hydroxylation #1: Liver (25)
Hydroxylation #2: Kidney (1) |
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What are the enzymes that hydroxylate Vit D during activation?
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P450 cytochromes
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What controls the synthesis of 1,25-dihydroxy Vit D in the kidney?
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-PTH
-PO4 levels |
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What is the function of activated Vitamin D?
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1. Binds VDR (receptor)
2. Heterodimerizes with RXR |
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What is RXR bound when it binds VDR?
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9-cis-retinoic acid
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What results from Vit D deficiency?
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-Rickets in kids
-Osteomalacia in adults |
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What results from excess Vit D?
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-Diarrhea, dermatitis,
-Headache, Bone Decalcifctn, -Kidney/heart damage -Retarded growth -Kidney stones. |
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What do Vit D and PTH regulate?
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Plasma calcium
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What causes increased synthesis of active Vit D?
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-Low plasma Calcium
-Increased PTH |
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What is Vit D used to treat?
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Calcium deficiency and osteoporosis
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How does Phosphate levels regulate Vit D synth?
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When PO4 is low, it DECREASES PTH and increases Vit D
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So what is Vit D involved in? (3 things)
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1. Reg of genes for Ca/PO4
2. Reg of genes for immune system and epithel cell functn 3. Reg of hormone levels |
