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Vitamins
identification, deficiencies, doses correlating with toxicity
| Question | Answer |
|---|---|
| Vitamin A | retinol, B-carotenes |
| Energy Releasing | Thiamine, Riboflavin, Niacin, Biotin, Pantothenic Acid |
| Functions of thiamine | formation or degradation of a-ketols by transketolase, oxidative decarboxylation of a-ketoacids: a-ketoglutarate to succinyl CoA, pyruvate to acetyl CoA |
| B2 | Riboflavin |
| B3 | Niacin |
| B6 | Pyridoxine |
| Hematopoietic | Folic acid, Vitamin B12 |
| Non B-Complex | Ascorbic acid (Vitamin C) |
| RDA of Vitamin D | 5 mg of cholecalciferol or 200 IU |
| K1, present in __ | phylloquinone, plants |
| Vitamin E | tocopherols |
| Fat soluble vitamin that serves as a coenzyme | Vitamin K |
| Consumption of Vitamins _ and _ in excess of RDA can lead to toxicity | A and D |
| Function of folic acid | receives 1 carbon fragments from donors and transfers them to intermediates in teh synthesis of amino acids, purines, and TMP |
| microcytic anemia (<80) | deficiency in: iron, copper, pyridoxine |
| normocytic anemia (80-100) | protein-calorie malnutrition |
| macrocyctic anemic (>100) | deficiency in Vitamin B12, folate |
| Megaloblastic anemia is caused by a | folate free diet |
| dihydrofolate reductase inhibitor | methotrexate |
| B12 | Cobalamin |
| Cobalamin functions | remethylation of homocysteine to methionine, isomerization of methylmalonyl CoA (rearrangement of carbons) |
| Cobalamin deficiency | abnormal fatty acids accumulate in cell membranes, including CNS |
| Form of cobalamin in homocysteine methylation | Methylcobalamin |
| Form of cobalamin in methylmalonyl CoA isomerization | Deoxyadenosyl-cobalamin |
| Corrin ring system seen in | cyanocobalamin |
| cobalamin is synthesized by | microorganisms, natural bacterial flora |
| Failure to absorb B12 from the intestine results in __ | pernicious anemia, commonly resulting from the autoimmune destruction of gastric parietal cells responsible for the synthesis of intrinsic factor |
| Function of Vitamin C | reducing agent in several different reactions, coenzyme in hydroxylation reactions, maintenance of normal connective tissue and wound healing, facilitates absorption of dietary iron from the intestine |
| Pyridoxine occurs primarily in __ | plants |
| Pyridoxal and pyridoxamine found in foods from ___ | animals |
| Pyridoxine is a precursor for coenzyme ___ | pyridoxal phosphate |
| Drug that induces Vitamin B6 deficiency | Isoniazid |
| Toxic dose of B6 | Greater than 2g/day |
| B6 reactions | transamination (OAA->Asp), deamination (Ser-> pyr + NH3), decarboxylation (histidine -> histamine + CO2), condensation |
| Biologically active form of B1 | thiamine pyrophosphate |
| Thiamine deficiency causes | decreased production of ATP and impaired cellular function |
| Thiamine deficiency diseases | Beriberi, Wernicke-Korsakoff |
| Beriberi | infants: tachycardia, vomiting, convulsions, death; adults: dry skin, irritability, disorderly thinking progressive paralysis |
| Wernicke-Korsakoff | dietary insufficiency of thiamine/impaired intestinal absorption of B1; apathy, memory loss, nystagmus (eyeball motion) |
| Function of niacin | REDOX reactions |
| Niacin's biologically active coenzyme forms | NAD+, NADP |
| NADPH function | electron donor for reductive biosynthesis |
| NADH function | generation of ATP |
| Niacin defiency causes | pellagra: dermatitis, diarrhea, dementia, death |
| Niacin is used in the treatment of __. Doses of ___ or 100 times the RDA ____ | hyperlipidemia (inhibits lipolysis in adipose tissue); 1.5g/day |
| Functions of Riboflavin | reversibly accepts 2 H atoms, bound tightly to flavoenzymes that catalyze the oxidation or reduction of a substrate |
| Riboflavin deficiency symptoms | dermatitis, cheilosis (fissuring at the corners of mouth), glossitis |
| Riboflavin is a ___ | prosthetic group |
| Functions of biotin | coenzyme in carboxylation reactions, carrier of activated CO2 |
| Source of biotin | intestinal bacteria |
| Pantothenic Acid is a component of ___ | CoA |
| contains a thiol group that carries acyl compounds as activated thiol esters | pantothenic acid |
| component of fatty acid synthase | pantothenic acid |
| Vitamin A deficiency | decreased growth rate and bone development in children |
| Vitamin A in reproduction | retinol and retinal support spermatogenesis in the male and prevent fetal resorption in the female |
| Retinoic acid promotes __ | growth and differentiation of epithelial cells |
| Vitamin A requirement | 1000 RAE for males, 800 RAE for females |
| 1 RAE = _mg of retinol, _ mg of B-carotene, _ mg of other carotenoids | retinol activity equivalent; 1, 12, 24 |
| Vitamin A toxicity | Greater than 7.5 mg/day of retinol |
| Vitamin A and Vitamin D cellular action | binds to intraceullular receptor proteins and interacts with DNA in the nucleus of target cells |
| Functions of Vitamin D | selectively stimulates gene expression or specifically repress gene transcription, regulates plasma levels of calcium and phosphorous |
| D2 | ergocalciferol; plants |
| D3 | cholecalciferol; animals |
| Vitamin D: ___ uptake of Ca by the __ and minimizes loss of Ca by the ___ | intestine; kidney |
| sources of pantothenic acid | eggs, liver, and yeast |
| Vitamin D deficiency causes | rickets |
| Nutritional Rickets | demineralization of bone |
| Renal Rickets caused by | inability to form active form of Vitamin D |
| hypoparathyroidism caused by __; results in ___ and __; treated with ___ and ____ hormone | Vitamin D deficiency; hypocalcemia and hyperphosphatemia; Vitamin D and parathyroid hormone |
| Toxicity of Vitamin D; causes | 100,000 IU for weeks or months; can cause loss of appetite, nausea, thirst, and stupor; hypercalcemia |
| Role of Vitamin K | posttranslational modification of various blood clotting factors |
| Vitamin K-dependent carboxylation of glutamic acid forms __; required in ___ | carboxygluatamate; hepatic synthesis of the inactive precursor molecules prothrombin and blood clotting factors II, VII, IX, and X |
| Dicumarol | anticoagulant naturally occuring in warfarin that inhibits formation of Gla |
| AI for Vitamin K | 70 to 140 mg/day |
| Vitamin K synthesis | intestinal bacterial flora |
| Hypoprothrombinemia | caused by 2nd generation cephalosporins; requires supplementation with Vitamin K |
| Prolonged administration of large doses of Vitamin K can produce ___ and ___ in infants | hemolytic anemia; jaundice |
| Active form of Vitamin E | a-tocopherol |
| Role of Vitamin E | antioxidant in prevention of the nonezymic oxidation of polyunsaturated fatty acids by O2 and free radicals |
| RDA of Vitamin E | 10 mg for men; 8 mg for women |
| Vitamin E Deficiency restricted to ____; associated with _____ in _____ | premature infants; defective lipid absorption or transport in adults |
| sources of preformed vitamin A | liver, kidney, cream, butter, egg yolk |
| 7-dehydrocholesterol -> cholecalciferol -> 25-hydroxycholecalciferol -> 1,25 - hydroxycholecalciferol | UV light, liver 25-hydroxylase, kidney 1-hydroxylase |
| carboxylation | biotin, Vitamin K |
| sources of cobalamin | dairy, eggs, pork, chicken |
| top sources of Vitamin C | papaya, red bell peppers, broccoli, brussel sprouts, strawberries |
| sources of niacin | milk, lean meats, especially liver |
| sources of carotenes | yellow/dark green fruits and vegetables |
| Vitamin A deficiency symptoms | night blindness, xerophthalmia, pathologic dryness of conjunctiva and cornea |
| K2, present in intestinal flora | menaquinones |
| sources of Vitamin K | green leafy vegetables, bright colored vegetables |
| sources of Vitamin E | vegetable oils, liver, and eggs |
| All of the following are essential fatty acids except? | palmitate acid |
Created by:
sreeja
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