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step 1 > biochem: nutrition > Flashcards

biochem: nutrition Flashcards

1
Q

fat soluble vitamins

A

ADEK. absorption depends on gut and pancreas. toxicity more common b/c they accumulate in fat. malabsorption w/steatorrhea e.g. CF, sprue, mineral oil intake

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2
Q

water soluble vitamins

A

all Bs, C. all wash out easily except B12 and folate, which are stored in liver. B-deficiencies -> dermatitis, glossitis, diarrhea

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3
Q

vitamin A

A

= retinol, like retin-A, used topically for wrinkles and acne. found in liver and leafy veggies

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4
Q

vit A fxn

A

antioxidant, part of visual pigments, essential for differentiation into specialized tissue, prevents squamous cell metaplasia, Tx for measles and AML subtype M3

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5
Q

vit A deficiency

A

night blindness, dry, scaly skin, corneal degeneration, bitot spots on conjunctiva, immunosuppression

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6
Q

vit A excess

A

acute tox: nausea, vomiting, vertigo, blurred vision. chronic tox: alopecia, dry skin, hepatic toxicity/enlargement, arthralgias, pseudotumor cerebri. teratogenic: cleft palate, cardiac abnormalities.

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7
Q

vit B1

A

= thiamine. mnemonic: ATP: Alpha-ketoflutarate dehydrogenase, Transketolase, and Pyruvate dehydrogenase.

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8
Q

vit B1 fxn

A

cofactor for dehydrogenase rxns as part of TPP (e.g. links glycolysis to TCA cycle, part of TCA cycle, HMP shunt, and branched-chain ketoacid dehydrogenase

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9
Q

vit B1 deficiency

A

impaired glucose breakdown -> ATP depletion worsened by glucose infusion; highly aerobic tissues affected 1st (brain, heart). Wernicke-korsakoff syndrome and beriberi. seen in malnutrition and alcoholism. Dx by inc. in RBC transketolase activity following B1 administration

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10
Q

wernicke-korsakoff syndrome

A

confusion, opthalmoplegia, atatxia (classic triad), + confabulation, personality change, memory loss. damage to medial dorsal nucleus of thalamus and mammillary bodies

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11
Q

dry beriberi

A

polyneuritis, symmetrical muscle wasting. Ber1Ber1

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12
Q

wet beriberi

A

high-output cardiac failure (dilated cardiomyopathy), edema. Ber1Ber1

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13
Q

vit B2

A

= riboflavin

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14
Q

vit B2 fxn

A

component of flavins FAD and FMN, used as cofactors in redox rxns (e.g. succinate dehydrogenase rxn in TCA cycle).

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15
Q

vit B2 deficiency

A

2Cs = Cheilosis (inflammation of lips, scaling and fissures at mouth corners), Corneal vascularization

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16
Q

vit B3

A

= niacin

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17
Q

vit B3 fxn

A

constituent of NAD+, NADP+. derived from tryptophan. synthesis requires B2 and B6. used to treat dyslipidemia; lowers VLDL and raises HDL. N(AD) derived from Niacin

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18
Q

vit B3 deficiency

A

3 Ds: Diarrhea, Dementia (+ hallucinations), and Dermatitis (C3/C4 dermatome: broad collar rash and hyperpigmentation of sun-exposed limbs. Also glossitis and severe -> pellagra. can be caused by hartnup dz (dec. tryptophan absorption), malignant carcinoid syndrome (inc. tryptophan metabolism) and isoniazid (dec. B6).

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19
Q

vit B3 excess

A

facial flushing (induced by prostaglandin, can avoid by taking aspirin with niacin), hyperglycemia, hyperuricemia

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20
Q

vit B5 fxn

A

= panto(“pento”)thenic acid = essential component of CoA, the cofactor for acyl transfers, and fatty acid synthase

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21
Q

vit B5 deficiency

A

dermatitis, enteritis, alopecia, adrenal insufficiency

22
Q

vit B6 fxn

A

= pyridozine. converted to PLP, a cofactor in transamination (e.g. AST, ALT), decarboxylation rxns, glycogen phosphorylase. necessary for synthesis of cystathionine, heme, niacin, histamine, 5HT, epinephrine, NE, DA, and GABA

23
Q

vit B6 deficiency

A

convulsions, hyperirritability, peripheral neuropathy (inducible by isoniazid and OCPs), sideroblastic anemia

24
Q

vit B7 fxn

A

= biotin = cofactor for carboxylation enzymes (add 1 C group): pyruvate carboxylase (pyruvate -> oxaloacetate), acetyl-CoA carboxylase (acetyl-CoA -> malonyl Co-A), and propionyl-CoA carboxylase (propionyl-CoA -> methylmalonyl-CoA

25
Q

vit B7 deficiency

A

= rare. dermatitis, alopecia, enteritis. caused by Abx use or excessive ingestion of raw egg whites

26
Q

vit B9

A

= folate. found in leafy greens. absorbed in jejunum. small reserve stored in the liver.

27
Q

vit B9 fxn

A

converted to THF, a coenzyme for 1-C transfer/methylation rxns. important for synthesis of bases in DNA and RNA.

28
Q

vit B9 deficiency

A

macrocytic, megaloblastic anemia, hypersegmented PMNs, glossitis, NO neuro symptoms. labs: inc. homocysteine, normal methylmalonic acid. most common deficiency in US. seen in EtOHics and pregnancy. also caused by phenytoin, sulfas, methotrexate. take folate to reduce risk of neural tube defects

29
Q

vit B12

A

= cobalamin. found in animal products. synthesized only by microorganisms. large reserve pool (several years) stored in liver. absorbed w/intrinsic factor in terminal ileum

30
Q

vit B12 fxn

A

cofactor for homocysteine methyltransferase and methylmalonyl-CoA mutase

31
Q

vit B12 deficiency

A

macrocytic, megaloblastic anemia, hypersegmented PMNs, paresthesias, subacute combined degeneration (abnormal myelin). inc. serum homocysteine and methylmalonic acid levels. prolonged deficiency -> irreversible nerve damage. caused by veganism, malabsorption, lack of intrinsic factor, or lack of terminal ileum

32
Q

pernicious anemia

A

anti-intrinsic factor Abs

33
Q

vit C fxn

A

= ascorbic acid. antioxidant. facilitates Fe absorption by reducing it to Fe2+ state. necessary for hydroxylation of proline and lysine in collagen synthesis. necessary for DA conversion to NE via beta-hydroxylase. Tx for methemoglobinemia b/c it reduces Fe.

34
Q

vit C deficiency

A

sCurvy due to Collagen synthesis defect. swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, “corkscrew” hair. weakened immune response

35
Q

vit C excess

A

nausea, vomiting, diarrhea, fatigue, Ca oxalate nephrolithiasis. can inc. risk of Fe toxicity (e.g. people w/chronic blood Tx)

36
Q

vit D

A

D2 = ergocalciferol, found in plants. D3 = cholecalciferol, consumed in milk, formed in sun-exposed skin (stratum basale). 25-OH D3 = storage form. 1,25-(OH)2D3 = cacitriol = active form.

37
Q

vit D fxn

A

inc. intestinal absorption of Ca and phosphate, inc. bone mineralization.

38
Q

vit D deficiency

A

rickets (bone pain and deformity) in children, osteomalacia (bone pain and muscle weakness) in adults. hypocalcemic tetany. deficiency exacerbated by no sun, skin pigment, and prematurity.

39
Q

vit D excess

A

hypercalcemia, hypercalciuria, dec. appetite, stupor. seen in granulomatous dz (inc. activation of vit D by epithelioid macrophages)

40
Q

vit E fxn

A

= tocopherol/tocotrienol. antioxidant, protecting RBCs and membranes from free radical damage. can enhance anticoagulant effects of warfarin

41
Q

vit E deficiency

A

hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar demyelination.looks like B12 deficiency but w/o megaloblastic anemia, hypersegmented PMNs, or inc. serum methylmalonic acid.

42
Q

vit K fxn

A

= phytomenadione, phylloquinone, phytonadione. cofactor for gamma-carboxylation of glutamic acid residues on various clotting factors - II, VII, IX, X, proteins C and S. made by intestinal flora. K = Koagulation. warfarin = vit K antagonist

43
Q

vit K deficiency

A

neonatal hemorrhage with inc. PT and aPTT but normal bleeding time. neonates have sterile intestines. can also be caused by prolonged use of broad spectrum Abx. not in breast milk so neonates are given an injection at birth

44
Q

zinc fxn

A

essential for 100+ enzymes. zinc fingers = transcription factor motif

45
Q

zinc deficiency

A

delayed wound healing, hypogonadism, dec. adult hair, dysgeusia, anosmia, acrodermatitis enteropathica. may predispose to alcoholic cirrhosis

46
Q

kwashiorkor

A

from a protein-deficient MEAL: Malnutrition Edema Anemia, Liver (fatty). = protein malnutrition -> skin lesions, edema (dec. oncotic pressure), liver malfunction (fatty change from dec. apolipoprotein synthesis). small child w/swollen abd.

47
Q

marasmus

A

Marasmus -> Muscle wasting. = total calorie malnutrition -> tissue and muscle wasting, loss of subQ fat, and variable edema

48
Q

fomepizole

A

inhibits EtOH dehydrogenase and is antidote for methanol or ethylene glycol poisoning

49
Q

disulfiram

A

inhibits acetaldehyde dehydrogenase -> accumulation of acetaldehyde -> hangover Sx

50
Q

NAD+

A

= limiting reagent in EtOH metabolism

51
Q

EtOH dehydrogenase…

A

operates via zero-order kinetics (enzyme = saturated, rate is not proportional to reagent [ ] )

52
Q

EtOH metabolism -> inc. NADH/NAD+ ratio in liver causing:

A

pyruvate -> lactate (lactic acidosis
oxaloacetate -> malate (prevents gluconeogenesis -> fasting hypoglycemia)
dihydroxyacetone phosphate -> glycerol-3-phosphate (combines w/fatty acids to make triglycerides -> hepatosteatosis)
–> clinical picture of chronic alcoholism.
also disfavors TCA production of NADH -> ketoacidosis and lipogenesis (-> hepatosteatosis)

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