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9 Cards in this Set
- Front
- Back
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Write out the full name(s) for Vitamin D
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1,25-dihydroxycholecaliferol
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How is VitD formed?
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UV light produces cholecalciferol
Liver adds a 25-hydroxyl group Kidney adds a 1-hydroxyl group Boom town |
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Describe the principle actions of Vitamin D
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Binds to VitD receptor and promotes gene transcription of certain proteins
TRPV6 and calbindin (gut) Maintains skeletal Ca balance by promoting absorption in gut, but also increases Oclast numbers and involved in PTH regulation |
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Any problems with XS intake?
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No, not realy. Can take 10,000 IU daily with no problem
200-800 IU RDA |
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Any problems with reduced intake?
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YES. Lots.
Osteomalacia - physis fused :::Impaired mineralisation of bone, accumulated unmineralised OSTEOID Rickets - physis present :::Newly formed bone at growth plate does not become mineralised so leads to abnormally wide, thick and irregular growth plates |
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What do we know about FGF23 and phosphate?
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FGF23 secreted by osteocytes in response to elevated (Vitamin D) calcitriol
Reduces absorption and promotes excretion of Phosphate in the renal tubules |
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Metabolic bone disorers can be malfunction in
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bone morpholgy or bone metabolism (function)
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Name diseases to match these situations:
Loss of mineralisation: Low bone mass: High bone mass: High bone turnover: Low Bone turnover |
Loss of mineralisation: Osteomalacia, rickets
Low bone mass: Osteoporosis, Osteogenesis Imperfecta High bone mass: Osteopetrosis High bone turnover: Pagets, hyperparathyroidism Low Bone turnover: Adynamic disease, hypophosphatasia |
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Tell me a little about Pagets
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High bone turnover (resorption and formation)
Disorganised structure Increased fragility/fracture risk |
