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USMLE
Biochem Nutrition
Question | Answer |
---|---|
Fat soluble vitamins | A D E K |
Where are fat soluble vitamins absorbed? | ileum, but also depends on pancreas |
B-vitamins | B1=thiamine B2=riboflavin B3=niacin B5=pantothenic acid B6=pyridoxine B12=cobalamin |
Vit A: Function? Deficiency? Source? Excess? | aka Retinol Function: constituent of visual pigment Deficiency: night blindness, dry skin Source: leafy greens, carrots (as a precursor B-carotene) Excess: Arthralgias, fatigue, HA, sore throat, alopecia |
Vit B1: Function? Deficiency? Source? | aka thiamine Function: cofactor for oxidative decarboxylation (TCA cycle: a-ketoglutarate->succinyl CoA), pyruvate dehydrogenase, and HMP shunt and branched AA dehydrogenase Deficiency: early lose appetite, peripheral neuropathy, later wernicke-korsak |
Vit B2: Function? Deficiency? | aka riboflavin (becomes FAD or FMN) Function: cofactor for red/ox of FAHDH2 (its converterd into FAD or FMN) Deficiency: cheliosis (angular stomatitis), corneal vascularization "think 2C's" |
Vit B3: Function? Deficiency? Source? | aka niacin Function: converted into NAD or NADP Deficiency:Pellagras: Diarrhea, Dermatitis, Dementia Source: from diet or converted into B3 from tryptophan (with the help of B6) "think 3D's" comment: tends to only occur in places that rely corn (low |
Vit B5: Function? | aka pantothenoic acid Function: constituent of CoA and Fatty Acid synthase |
Vit B6: Function? Deficiency? | aka pyrixodine Function: cofactor for transammination, decarboxylation, heme synth, & conversion of tryptophan into Vit B3 Deficiency: Sideroblastic anemia (microcytic) convulsions, irritability, peripheral neuropathy. Def induced by INH & OCPs |
Vit B12: Function? Deficiency? Source? | aka cobalamin Functions: 1)converts methyl-THF into THF which is needed for nucleotide synthesis. 2) converts homocysteine into methionine 3) allows odd chain fatty acids to enter the TCA cycle (as succinyl CoA) Deficiency: megaloblastic/macrocytic an |
Biotin: Function? Deficiency? | Cofactor conversion of acetyl coA into fatty acid deficiency: causes dermatitis and enteritis |
Vit C: Function? Deficiency? | aka ascorbic acid Function: collagen synth, iron absorption, conversion of dopamine into NE Deficiency: causes Scurvy (swollen gums, bruising, anemia, poor wound healing) |
Vit D: Function? Deficiency? Source? Forms? | Function: increases intestinal absorption of Ca and PO4 Deficiency: causes rickets (kids), osteomalacia (adults), and hypocalcemia (tetany) Source: D2 from fortified milk D3 from sunlight conversion in skin Forms: 25-OH D3 = storage form, 1,25(OH)2 D |
Vit E: Function? Deficiency? Excess? | Function: antioxidant (esp protects RBCs) Deficiency: neurolodysfunction and hemolytic anemia (due to incr fragility of erythrocytes) Excess: can interfere w/Vit K |
Vit K: Function? Deficiency? Source? | Function: Catalyzes gamma-carboxylation of glutamic acid residues. needed for clotting factors 2, 7, 9, 10, proteins C & S Deficiency: causes clotting defects (bleeding, bruising, increased PT time) Source: Intestinal flora |
Zinc: Function? Deficiency? | Function: cofactor for many metalloenzymes deficiency: causes delayed wound healing, hypogonadism (less adult hair, etc), may presdispose to alcoholic cirrhosis |
Kwashiorkor | protein deficient "MEAL". Clinical pic is small child w/swollen belly M=malnutrition E=edema A=anemia L=liver (fatty) |
Maramus | Energy malnutrition (not enough calories) causes depletion of subcutaneous fat and muscle wasting. "typical starvation" |