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32 Cards in this Set
- Front
- Back
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what is a vitamin
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- An organic substance required in small amounts for normal metabolism, but which cannot be synthesized by the body in sufficient quantities
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what are the water solubles ?
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B, C
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what are the fat solubles
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ADEK
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name 2 factors which increase availability of vitamins
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provitamins
eg beta carotene, tryptophan - Colonic bacteria: Required for vitamin K, B12, folate |
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name 2 factors which decrease availability of vitamins
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biliary dysfunction - decrease vit K
binding: eg nicotinic acid bound to maize |
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where is vitamin C stored?
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pituitary gland
plasma skeletal muscle leucocytes |
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how long do stores last?
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3-6 months
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where is vit A and D stored
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liver and alminetary tract
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where is vitamin B12 stored?
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liver
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what are the functions of water soluble vitamins?
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1) intermediary metabolism
2) anaemia preventing 3) antioxidants |
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what are the funcitons of B1
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thiamine: dehydrogenase enzyems
- pyruvate - a-ketogluterate - isocitrate |
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what is the function of nictoninc acid
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NAD
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where is thiamin found?
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plant seed, cereals, rice
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how does deficiency occur?
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eat too much raw fish; contains thiaminases
eat polished rice chronic alcoholism |
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what is deficiency and what happens?
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beri beri
wet and dry neuropathy dry encephalopathy wet cardiomegaly and odema wet |
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where is nicotinic acid found
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fish, liver, cereals - tryptophan a precursor
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what is deficiency and what is it characterised by?
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pellagra
dementia: neurolgocial disease digestive problem; disease, underweight dermatitis: rough skin, dermatitis, photosensitive, erythema |
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how does it happen?
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through diet eg eating maize
chronic alcoholism |
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what is the name for B12
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folate
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where is B12 found?
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foliage - green veg
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what happens in folate deficiency?
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anaemia
neural tube defects |
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how is b12 absorbed?
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requires intrinsic factor, prdouced in stomach, acts in duodenum
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what is the affect of B12 deficiency?
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megaloblastic anaemia
neuropathy due to decreased myelin production |
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how are B12 and B9 related
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B9 produced when homocysteine methylated to methionine.
B12 dependant reaction |
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vitamin A is found in...
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animal products only!
precursor B carotene in carrots / veg but slow to convert, also affected by dietary factors i.e. increased intake = decreased absorption |
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actions of vitamins A?
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needed for rhodopsin: vision in dim light/ peripheral vision
epithelial maintenance - regulates keratin maintains health of mucous membrane gene expression: binds to RAR and RXR |
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deficiency:
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night blindness
xerophtamia keratomalacia |
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can it be toxic?
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yes - chronic causes
CSF pressure increase hepatomegaly teratogenesis and birth defects |
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sources of vitamin D?
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D3 in FEB, fish oils, egg yolk, butter
as dehydrocholesterol in animal fats and plant sterols - turned to D3 by uv light |
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how is it metabolised?
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first by liver to form calcidiol: then hydroxylated again by kidney to form calcitriol -active form
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deficiency?
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rickets in children
osteomalacia in adults |
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toxicity?
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yes
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