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Biochem 2 - PCC
Fat soluble vitamins
| Question | Answer |
|---|---|
| What are the fat soluble vitamins? | A D E K |
| How are they transported? | In chylomicrons |
| Are they able to be stored? | Yes, liver and adipose tissue |
| Are they toxic in large amounts? | Yes |
| Oxidation of vitamin A | 1. Retinol 2. Retinal 3. Retinoic acid |
| Retinol | Reproduction and growth |
| Retinal | Eyes, vision |
| Retenoic Acid | Cell differentiation |
| Where can you find preformed vitamin A? | In animal products and Retinol Esters (RA) |
| Where can you find proformed vitamin A? | In plant products (red, orange, yellow) |
| What can be oxidized if your vitamin A content is too low? | Retinal |
| Vitamin a deficiency leads to what? | Vision problems but rare in developped nations |
| What happens if you take too much vitamin A ? (toxicity) | 1. Can lead to defects in pregnant woman 2. Months of overconsuming caretenoids can lead to orange skin 3. Supplements of any kinds should not be taken by smokers |
| What are caretenoids and RE bound to in food? | Fatty acid and protein |
| What strips the protein part from the vitamin A? | Pepsin in the stomach and protease in the small intestin |
| What strips the fatty acid from the vitamin A? | Prancreatic RE hydrolayse or esterase in the brush border |
| What is the role of bile in vitamin A? | Makes it soluble |
| Where do the retinol and carotenoids incorporate themselves in order to be digested? | In the micelles |
| How is vitamin A a brought into the duodemnum and jejunum? | Through passive diffusion |
| Where is the retinol reesterified and by what? | In the enterocytes by lecithin: retinol acyl transferase (LRAT) |
| In vitamin A absorption, what are the RE incorporated into? | Chylomicrons |
| What happens if retinol intake is low? | Carotenois are metabolized to 2 retinals: 1. Bound by CRBP, reduced to retinol, esterified via LRAT and incroporated into chylomicrons or 2. oxidized to retinoic acid and travels to the liver bound to albumin |
| What does vitamin D work with in order to regulate blood calcium? | Parathyroid hormone |
| What is the name of active vitamin D? | Calcitrol |
| What happens in relation to vitamin D when calcium is too low? | 1. Increased absorption of calcium and phosphorus in small intestine 2. Decreases calcium excreation in kidneys 3. Removes calcium and phosphorus from bone to increase concentration in blood. |
| What is synthesized when blood calcium is low? | Calcitrol |
| What does calcitrol affect? | 1. Cell differentiation 2. Cell growth 3. Cell proliferation |
| What is topical calcitrol used for? | Psoriasis |
| Why are obese patients sometimes lacking in vitamin D? | Because adipose tissue acts as a sink for vitamin D. |
| Vitamin D deficientcy can lead to what? | Rickets, type 1 diabetes, MS, RA and Crohn's disease |
| What type of digestion is associated with vitamin D? | No digestion necessary |
| How is Vitamin D absorbed? | It is incorporated into micells and absorbed via passive diffusion in the small intestine |
| How is vitamin D transported? | 40% chylomicrons 60% is bound to vitamin D-binding protein (DBP) and transported into the blood |
| Where is vitamin D3 made? | In the skin |
| Once vitamin D3 is bound to DBP where does it go? | To the liver but it may be picjed up by muscle or adipose tissue before reaching the liver |
| What happens to vitamin D3 once it reaches the liver? | It is hydroxylated and released back into the blood |
| What happens to the vitamin D that reaches the kidneys? | It is hydroxylated again to form calcitrol |
| What are the functions of vitamin E? | 1. Membrane integrity 2. Helps stop reactions involving free radicals 3. May decrease LDL oxidation |
| What is the diffrence between vitamin E supplement and dietary vitamin E? | It is not nearly as active |
| What does large doses of vitamin E interfere with? | Other fat soluble vitamins |
| Vitamin E transport | hg |
| hgtrf | htyf |
| Vitamin K functions | 1. Blood clotting 2. Bone formation |
| What is vitamin k dependant on in relation to blood clotting and bone formation? | Carboxylation of glutamic acid |
| What can alter the vitamin K pathway? | Anticoagulants such as coumadin |
| Digestion of vitamin K | No digestion necessary |
| How is vitamin K incorporated into the micelles? | With the help of bile |
| Where is vitamin K abosorbed? | 1. Small intestine 2. Ileum 3. Colon |
| How is vitamin K transported? | It is packaged in chylomicrons |
| Vitamin A deficientcy leads to what? | 1. Vision problems 2. Decrease immune function |
| Excess vitamin A can cause what? | 1. Birth defects 2. Yellow/orange skin 3. Decreased acne (retenoic acid) |
| Function of vitamin D | 1. Increase in Ca and P absoption in SI 2. Decrease calcium excreation in kidneys 3. Removes Ca from bone to increase the Ca concentration in blood 4. Stimulates cell differentiation |
| Vitamin E Functions | Antioxydant : 1. Membrane intergrity 2. Hinders free radicals 3. Decreases LDL oxidation |
| Functions of vitamin K | 1. Blood clotting 2. Bone formation (glutamic acid) |
| Where is endogenous vitamin K produced and what is its name? | Made by bacteria in large intestine and named menaquinone |
| Exogenous vitamin K is called what and found where? | Phylloquinone and found in plants |
| Vitamin B12 digestion: 3 steps | 1. Protein releases by HCL and pepsin in stomach 2. B12 binds to R Protein. R Protein is removed by proteases. 3. B12 binds to intrinsic factor which is secreted by the parietal cells |
| Vitamin B12 is absorbed as what and where? | It is absorbed by B12-IF complex by receptor mediated endocytosis in illeum |
| Can vitamins be stored in the body? | Yes, fat soluble vitamins can as well as B12 |
| What makes vitamin A soluble? | Bile : Proteases in the stomach |
| Through what mechanism is vitamin A absorbed? | Passive diffusion |
| Where is preformed vitamin A found? | 1. Animal products 2. Retinol esters |
| Where is proformed vitamin A found? | In orange, yellow and red plant products |
| In what instance does our body use carotenoids instead of retinol for vitamin A? | If it is low but it is much slower |
| In the enterocytes, vitamin A is bound to what and reesterified by what? | Bound to CRBP and reesterified by LRAT |
| Proformed vitamin A is oxidized to form what? | Retinal |
| If vitamin A levels are low, it is reduced to what? | Retinol |
| If vitamin A levels are low, it is reduced to retinol and esterified by what? | LRAT |
| Retinal is oxidized to what? | Retinoic acid |
| What is the function of retinol? | Reproduction and growth |
| What is the function of retinal | Vision |
| What is the function of retinoic acid? | Cell differentiation |
| What is the active form of vitamin D? | Cacitrol |
| Natural tocopherols require what kind of digestion? | None |
| Synthetic tolopherols require what kind of digestion? | Esterases |
| Tocotrienols require what kind of digestion? | Esterases |
| What is precursor to vitamin D? | Cholesterol (dehydrocholesterol) |
| Obese patients may be lacking in what vitamin? | D |
| Is there any digestion required for vitamin D? | No! |
| How is vitamin D absorbed? | Passive diffusion as vitamin D3 (inactive) |
| Vitamin D is absorbed in what form? | D3 - Inactive |
| Vitamin D binding protein (DBP) transports vitamin D to where? | Kidneys and Liver |
| Are vitamin E supplements as active s dietary vitamin E? | No |
| Vitamin A and E are both what? | Esterified |
| What does esterified mean? | Bound to a fatty acid |
| How are vitamin A and E packed? | Chylomicrons |
| What kind of digestion for vitamin K? | None |
| What helps absorbe vitamin K? | Bile |
| Vitamin K in packed into what for transport? | Chylomicrons |
| Digestion of vitamin A | Proteases in stomach and SI... esterase removes FA |
| Absorption of vitamin A | Passive diffusion in SI and reesterified in enterocytes |
| Transport for vitamin A | RE and carotenoids are packed in chylomicrons where retinoic acid is packed in albumin |
| Absoprtion for vitamin D | Passive diffusion in micelles |
| Transport of vitamin D | 40% chylomicrons and 60% DBP (calcitrol) |
| Digestion of synthetic vitamin E | Esterase |
| Aboprtion of phyloguinone | Passive diffusion into micells |
| Absorption of menquinone | Passive diffusion into ileum and LI |
| Transport of vitamin E | Cylomicrons |
| Is digestion needed for vitamin C? | No, Ascorbic acid is oxidized into dehydroascorbic acid |
| How is ascorbic acid absorbed? | Active transport: SVCT1 and SVCT2 |
| How is dehydroascorbic acid absorbed? | Facilitated diffusion: it is quickly reduced back to ascorbic |
| Absorption of vitamin C increases or decreases with consumption? | Decreases |
| What also decreases absorption of vitamin C? | Glucose, Large doses of iron |
| Vitamin C is transported via what? | Free ascorbic acid in plasma |
| What is the natural form of folate? | Folate |
| What is the synthetic form of folate? | Folic acid |
| What type of digestion for folic acid? | None |
| What type of digestion for folate? | Residue need to be removed with conjugase in brush border. Glutamate is removed by conjugase in SI. |
| Folate is absorbed by what? | By active transport (foods) or by passive diffusion (pharmacological doses) in the SI. Whithin the enterocyte folate is reduced to tetrahydrofolate and methylated to 5-methyl THF |
| What are the carriers for folate? | Folate binding protein (FBP) and reduced folate transporter (RFT) |
| How is 5-methyl tetrahydrofolate transported? | It is transported as free in the plasma |
| B12 is transported via what in blood? | Trancobalamins |
| Ca is absorbed via what carrier? | Calbindin 9K |
| How is calcium transported? | It can be transported freely as calcium or bound to albumin or prealbumin |
| What is and example of a sphingophosphatide and where is it found? | Spingomyelin and it is found in plasma membranes of animal cells and in the myelin sheaths of the nerves |
| Name 2 sphingolipids but that are not sphingophospatides | 1. Cerebroside 2. Ganlioside |
| How are gangliosides diffrent than cerebrosides? | Cerbreoside is a ceramide + glucose or galactose and a ganglioside is a ceramide + oligosaccharide |
| Tay-sachs | Ganliosides |
| Neimann-pick | Spingomyelin |
| Sandhoof's | Gangliosides |
| Gaucher's | Glucocerebroside |
| Farber | Ceramide |
| Krabbe | Galactocerebroside |
| What is important for determing blood type? | Gangliosides |
| Ceramides are composed of what? | Sphingosine + Fatty acid |
| What is the function of gangliosides? | Cell signaling |
Created by:
LrB
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