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Vitamins
Biochem
15
Medical
Graduate
03/29/2013

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Cards

Term
Vit A (retinol)
Definition
Function - antixoidant; constitutent of visual pigments; essential for normal differentiation of epithelial cells into specialized tissue; prevents squamous metaplasia.
Used to treat measles and AML (M3)
Defic - night blindness, dry skin
Excess - arthralgias, fatigue, headaches, skin changes, sore throat, alopecia; teratogenic
Term
Vit B1 (thiamine)
Definition
Function - found in thiamine pyrophosphate (TPP), a cofactor for several enzymes in decarboxylation reactions: PDH, a-ketoglutarate dehydrogenase, transketolase, branched-chain amino acid dehydrogenase
Defic - impaired glucose breakdown; Wernicke-Korsakoff syndrome and beriberi; seen in malnutrition as well as alcoholism
Term
Vit B2 (riboflavin)
Definition
Function - cofactor in oxidation and reduction (FAD, FMN)
Defic - cheilosis, corneal vascularization
Term
Vit B3 (niacin)
Definition
Function - constituent of NAD+, NADP+; derived from tryptophan; synthesis requires B6
Defic - glossitis; severe defic leads to pellagra (diarrhea, dermatitis, dementia)
Excess - facial flushing
Term
Vit B5 (pantothenate)
Definition
Function - essential component of CoA and fatty acid synthase
Defic - dermatits, enteritis, alopecia, adrenal insuffiency
Term
Vit B6 (pyridoxine)
Definition
Function - converted to pyridoxal phosphate, a cofactor for transamination, decarboxylation reactions, glycogen phosphorylase; synthesis of cystathionine, heme, niacin, histamine, and neurotransmitters including serotonin, epinephrine, norepinephrine, and GABA
Defic - convulsions, hyperirritability, periph neuropathy, sideroblastic anemias
Term
Vit B7 (biotin)
Definition
Function - cofactor for carboxylation enzymes: pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase
Defic - dermatitis, alopecia, enteritis; caused by antibiotic use or excessive ingestion of raw eggs
Term
Vit B9 (folic acid)
Definition
Function - converted to THF, a coenzyme for 1-carbon transfer/methylation reactions; important for synthesis of nitrogenous bases in DNA/RNA
Defic - macrocytic, megaloblastic anemia; no neuro symptoms; most common vit defic in US; seen in alcoholism and pregnancy
Term
Vit B12 (cobalamin)
Definition
Function - cofactor for homocysteine methyltransferase and methylmalonyl-CoA mutase
Defic - macrocytic, megaloblastic anemia, hypersegmented PMNs, neurologic symptoms due to abnormal myelin; prolonged defic leads to irreversible nervous system damage
Term
S-adenosyl-methionine (SAM)
Definition
ATP + methionine
Function - transfers methyl units
Regeneration - dependent on B12 and folate
Term
Vit C (ascorbic acid)
Definition
Function - antioxidant; keeps iron in Fe+ reduced state to facilitate absorption; necessary for hydroxylation of proline and lysine in collagen synthesis; necessary for dopamine B-hydroxylase, which converts dopamine to NE
Defic - Scurvy - swollen gums, bruising, hemarthrosis, anemia, poor wound healing; weakened immune response
Excess - nausea, vom, diarrhea, fatigue, sleep problems
Term
Vit D
Definition
D2 - ingested from plants; D3 - consumed in milk, formed in sun exposure
25-OH D3 - storage form; 1,25-(OH2) D3 - active form
Function - inc intestinal abs of calcium and phosphate; inc bone mineralization
Defic - Rickets in children, osteomalacia in adults, hypocalcemic tetany
Excess - hypercalcemia, hypercalciuria, loss of appetite, stupor; seen in sarcoidosis
Term
Vit E
Definition
Function - antioxidant (protects erythrocytes and membranes from free-radical damage)
Defic - inc fragility of erythrocytes, muscle weakness, posterior column and spinocerebellar tract demyelination
Term
Vit K
Definition
Function - catalyzes gamma-carboxylation of glutamic acid residues on various proteins concerned with blood clottiing (II, IV, IX, X, prots C and S); synthesized by intestinal flora
Defic - neonatal hemorrhage with inc PT and inc aPTT but normal bleeding time; also after broad-spectrum antibiotic use
Term
Zinc
Definition
Function - essential for activity for 100+ enzymes; formation of zinc fingers Defic - delayed wound healing, hypogonadism, dec adult hair, dysgeusia, anosmia; may predispose to alcoholic cirrhosis
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