vitamins 3 Flashcards
what is the function of fat soluble vitamins
- cell growth
- maturation
- gene regulation
- vision
- bone formation
- antioxidants
- blood clotting
how are fat soluble vitamins absorbed
- absorbed with dietary fat
- transported away from small intestine in chylomicrons via blood and lymph
- liver either stores or repackages it to delivery for other cells
- excess vitamins accumulate in liver and adipose
what is vitamin A - retinol used for in the body
- synthesis of RNA
- vision
- reproduction
- embryonic development
- morphogenesis
- growth
- cellular differentiation
- apart from vision most are related to gene extrusion with vitamin A metabolites
what are the retinoids
- retinol - synthesised from retinal
- retinal - converted to retinoid acid
- retinoic acid
what are the carotenoids
- provitamin A carotenoids
- non-provitamin A carotenoids
how is most vitamin A stored
- in the liver in the form of retinyl esters
how is vitamin A and carotenoids regulated in the body
1) contained in chylomicrons
2) enter lymph
3) join blood at thoracic duct
4) delivered to adipose tissue, muscle and eye
5) what is not used is taken back to liver
6) carotenoids packaged into VLDLs
7) vitamin A attached to retinol binding proteins and transthyretin
what does lutein do
- may decrease growth of breast tumours
what does lycopene do
- related to lower risk of prostate caner
what does lutein and zeaxanthin do
- related to decreased risk of macular degeneration
what foods is beta-carotene found in
- carrots
- sweet potatoes
what foods is lycopene found in
- tomatoes
- pink grapefruit
- apricots
- watermelon
what foods is lutein found in
- dark green leafy vegetables
what is the symptoms of vitamin A deficiency disorder (VADD)
- increased risk of infection
- hyperkeratosis
- night blindness
- xerophthalmia - dry eyes
what is the form of vitamin A essential for vision
- 11-cis-rentinal
- essential component of rhodopsin
what is retinoic acid essential for
- compound in the retina that consists of the protein opsin and vitamin cis-retinal needed for night vision
- a protein that absorbs light in the retinal receptors
- supports the normal differentiation and functioning of the conjunctive membrane and cornea
that are the symptoms of hypervitaminosis A
- blurred vision
- liver abnormalities
- reduced bone strength
- birth defects
- increased risk of lung cancer
- hypercarotenemia
what is the therapeutic effect of vitamin A
11-cis-retinal oxidised to retinoic acid which is used inn hormonal signalling to epithelial cells
what os the functions of vitamin D - cholecalciferol
- synthesised in the skin
- regulates the absorption of phosphorus and calcium during bone growth
- enhances immune function
- improves muscle strength
how is vitamin D activated
- activated by parathyroid hormone (PTH)
- acts greatly increases the amount of calcium that the intestine can absorb from food
what is the name for a vitamin D deficiency
rickets
what is the use of vitamin E - tocopherol in the body
- maintenance of membrane integrity in virtually all cells of the body
- antioxidant
- non-antioxidant functions have also been proposed eg. modification of gene transcription and expression
where is vitamin E found and synthesises
- synthesised only in plants
- highest levels in fatty tissue
why is vitamin E an antioxidant
- reducing reagent that scavenges oxygen and free radicals
- helps protect polyunsaturated fatty acids in phospholipid membrane from oxidative damage
- picks up electrons from lipid free radical species
what happens with a vitamin K deficiency
- clotting disorders - prolonged bleeding and bruising
- decreased bone mineral density
- menorrhagia
