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20 Cards in this Set
- Front
- Back
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Deficiencies in vitamin A cause what clinical outcomes?
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Blindness, abortion, defects in epithelium
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What are some sources of vitamin D?
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milk, UV-B radiation, eggs, fish oils
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What is deficiency of vitamin E associated with, clinically?
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Infertility
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Where can vitamin K be found (sources, not storage)? What is another name for vit K?
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gut flora, dark green leafy vegs, vegetable oils. phylloquinone.
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Other names for A, D, E?
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Retinol (A), calciferol (D), tocopherol (E)
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What is the chromophore of rhodopsin?
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11-cis-retinal (form of vitamin A), active form
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What condition is caused by over-absorption of vitamin A? What are the symptoms?
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hypervitamintosis A - loss of appetite, abnormal skin pigmentation, loss of hair and dryness of skin
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What protein is retinol bound to within the intestinal epithelia? in cells?
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CRBP type II (cellular retinol binding protein); type I in other cells
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How does retinol function in cellular differentiation? Which genes targeted in embryogenesis?
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By functioning as a steroid-like hormone, regulating transcription. all-trans or 9-cis will bind to RAR/RXR, thereby activating (or inhibiting) transcription; Hox (homeobox) genes.
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What metabolite of vitamin D increases calcium absorption in the gut?
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calcitriol
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What factors +/- levels of 1, 25-OH-D?
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Phosphorus, calcium, 1,25-OH-D (through negative feedback), FGF-23, PTH
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What hormone controls the interaction between calcitriol and serum calcium? How?
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PTH. When serum Ca is low, PTH increases, which activates 1,25-OH-D (calcitriol) production in the kidney. 1, 25-OH-D3 binds to osteoblast RANKL (receptor activator of nuclear factor B ligand), which induces osteoclast maturation. Mature osteoclasts remove calcium and phosphorus from bone, maintaining Ca/Phosporus levels in circulation
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What form of vitamin D is given to patients with chronic renal failure?
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1, 25-OH-D3
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What is the antioxidant role of vitamin E? (Where in the cell is it located?)
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Protects membrane against oxidation; located within phospholipid bilayer (head sticks out to donate H groups to passing radicals)
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Tocopherol (vitamin E) is carried by what two macrostructures in circulation? What proteins carry E in plasma?
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micelles (gut) and chylomicrons (intestinal mucosal cells); lipoproteins VLDL, LDL; erythrocytes
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Major sources of vitamin E?
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vegetable oils. Also dairy products, fruit, eggs.
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Supplements of vit E may reduce what disease?
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CHD
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How does vitamin K increase calcium binding?
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vitamin K is a coenzyme for a carboxylase that adds a carboxyl group to factors 2, 7, 9, and 10, which increase calcium binding necessary for the formation of a clot
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What is are the major dietary and nondietary sources of vitamin K?
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Dietary - phylloquinone (dark green leafy vegetables). Non dietary - intestinal bacteria producing vitamin K.
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Vitamin K is absorbed along with dietary fats in what structure? Where does it eventually go?
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chylomicra, liver
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