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non protein component of an enzyme |
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why aren't vitamins made by organisms? |
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requires energy for synthesis control of synthesis is metabolically expensive cheaper to get nutrients from diet |
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vitamin D, vitamin E, Vitamin A, vitamin K
absorption dependent on fat absorption pathway; fat malabsorption may cause deficience |
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thiamin, riboflavin, niacin, B-6, B-12 (cobalamin) biotin, pantothenic, folate, C (ascorbic acid), choline
dissolve in watery components of foods and the body, excreted in urine, most are not stored, generally nontoxic, have unique membrane transport proteins |
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fat soluble antioxidant, protects membrane unsaturated FA's alpha-tocopherol (in liver transported by high affinity binding alpha-TTP) deficiency results in HEMOLYTIC ANEMIA AND PERIPHERAL NEUROPATHY |
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most active form is Retinol and is a constituent of Retinal visual pigment one of the few caretenoids (beta carotene) that the body can convert to retinol in excess (polar bear liver consumption) can be lethally toxic deficiency can lead to night blindness (quickly use retinol and can't refocus in dim lighting) and dry skin (xeroderma) |
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sunshine vitamin intestinal Ca2+ absorption and regulation through dietary fat pathway 7-dehydrocholesterol-->D3-->25 hydroxycholecalciferol(calcidiol)--> 1,25-dihydroxycholecalciferol (active calcitriol
requires sunlight, liver and kidney processing calcium can be absorbed paracellularly or transcellularly with vitamin D synthesis of Calcium channels, pump and exchange; also induces formation of carrier--> calbindin in duodenum Vitamin D deficiency=rickets in children and osteomalacia in adults (soft and deformed bones) (maybe caused by diarrhea and vomiting) tetany: involuntary muscle contraction in excess = hypercalcemia, hypercalciuria, loss of appetite and stupor Liver disease or kidney disease may impair the conversion to calcitriol |
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cofactor of carboxylation of glutamic acid residues, synthesis of prothrombin and other blood coagulation factors absorbed in jejunum and ileum from plants, animals and intestinal bacteria (large intestine) deficiency= hemorrhagic disease (rat poison) and bleeding gums warfarin is a vitamin K antagonist (coronary artery disease) |
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disorders causing fat soluble vitamin deficiency |
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cystic fibrosis: decreased pancreatic enzymes celiac sprue: decreased absorptive surface area laxative abuse steatorrhea: excess fat in feces chronic liver disease disorders of fat metabolism disorders of bile secretion |
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often work together and are present together in many of the same foods |
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thiamin is a cofactor in glycolysis, TCA cycle, HMP shunt, and BCAAD in low concentrations it is actively transported, in high concentrations it is passively transported (jejunum and ileum) deficiency = beriberi (polyneuritis and muscle wasting) wernicke-korsakoff syndrome: degenerative brain disorder frequent in alcoholics korsakoff's: amnesia and memory problems |
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used in redox reactions (NAD, NADP) from tryptophan and requires B6 for synthesis deficiency: pellagra (4D's dermatitis, diarrhea, dementia, death) Hartnup's Disease: inability to absorb dietary tryptophan results in niacin deficiency |
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used to synthesize DNA, purines, and thymine PteGlu1 is absorbed by an apical folate-OH exchanger (small intestinal brush border peptidase) deficiency =megaloblastic anemia (RBC's don't split apart) neural tube defects: high AFP, spinal bones fail to enclose the spinal cord and spina bifida |
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deficiency: rare and may come from avidin which binds biotin and prevents absorption; dermatitis, alopecia, enteritis |
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absorption is a multistep process: salivary glands secrete R-binder protein; low gastric pH liberates protein-bound B12 and it is bound to R binder protein in stomach; IF is released from gastric parietal cells; pancreatic proteases release B12 from R-binder; B12 binds IF in duodenum, and it is absorbed in ileum deficiency: can occur with lack of IF or intestinal malabsorption; various symptoms= megaloblastic anemia, subacute combined degeneration of spinal cord tracts, irritability/personality change/depression macrocytosis anemia with hypersegmentatio nof polymorphonuclear cells |
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B12 deficiency due to lack of Intrinsic factor
antibodies commonly seen : anti IF antibodies and anti parietal cell antibodies |
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problems with synthesis of blood cells with B12 or folate deficiency |
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deficiency of hemoglobin production; iron deficiency or thalassaemia |
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>100 macrocytic anemia 80-100 normocytic anemia <80 microcytic anemia |
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subsequent early increase in homocysteine--> elevated risk of coronary artery disease
folate lowers homocysteine levels with B12 and B6
folate may mask B12 deficiency anemia; B12 is used to recycle folate so it can revers the anemia if folate is supplemented but there will still be neurological problems from the B12 deficiency |
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Vitamin C (ascorbic acid) |
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couples with vitamin E for antioxidant activity keeps iron in reduced state (more absorbable) necessary for collagen synthesis absorbed by sodium dependent transporters deficiency = scurvy (can't synthesize collagen properly, gum bleeding, poor wound healing, pinpoint hemorrhage) |
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antioxidant use; free radical is absorbed by vitamin E so that it doesn't damage bonds in cell membrane and the electron is transferred to vitamin C on the other side of the membrane |
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