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USMLE 1 > Biochemistry- Nutrition > Flashcards

Biochemistry- Nutrition Flashcards

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USMLE® Step 1 flashcards
1
Q

Vitamins: fat soluble

A

A, D, E, K. Absorption dependent on gut and

pancreas.

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2
Q

B-complex deficiencies often result in…

A

dermatitis, glossitis, and diarrhea.

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3
Q

Wich Vitamins: water soluble wash out easily from body

A

All except B12 and B9 (folate). B12 stored in liver for ~ 3–4 years. B9 stored in liver for ~ 3–4 months

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4
Q

Vitamins: water

soluble

A 
B1 (thiamine: TPP)
B2 (riboflavin: FAD, FMN)
B3 (niacin: NAD+)
B5 (pantothenic acid: CoA)
B6 (pyridoxine: PLP)
B7 (biotin)
B9 (folate)
B12 (cobalamin)
C (ascorbic acid)
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5
Q

Vitamin A (retinol) FUNCTION

A
  • constituent of visual pigments
  • essential for normal differentiation of epithelial cells into specialized tissue.
  • prevents squamous metaplasia.
  • Used to treat measles and acute promyelocytic leukemia (APL).
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6
Q

Use oral isotretinoin to treat..

Use all-trans retinoic acid …

A
  1. severe cystic acne.

2. to treat acute promyelocytic leukemia

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7
Q

Vitamin A (retinol) DEFICIENCY

A

(nyctalopia) ; (xerosis cutis); corneal degeneration

(keratomalacia) ; Bitot spots on conjunctiva; immunosuppression

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8
Q

Vitamin A (retinol) EXCESS

A

Acute toxicity—nausea, vomiting, vertigo, and blurred vision.

Chronic toxicity—alopecia, dry skin (eg, scaliness), hepatic toxicity and enlargement, arthralgias, and pseudotumor cerebri.

Isotretinoin is teratogenic.

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9
Q

Vitamin B1 (thiamine)FUNCTION

A

Think ATP: α-ketoglutarate dehydrogenase,

Transketolase, and Pyruvate dehydrogenase.

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10
Q

Vitamin B1 (thiamine) DEFICIENCY

A

Spell beriberi as Ber1Ber1 to remember
vitamin B1

Wernicke-Korsakoff syndrome—confusion,
ophthalmoplegia, ataxia (classic triad)

Dry beriberi—polyneuritis, symmetrical muscle
wasting.

Wet beriberi—high-output cardiac failure
(dilated cardiomyopathy), edema.

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11
Q 
Vitamin B2 (riboflavin)
FUNCTION
A

FAD and FMN are derived from riboFlavin
(B2 ≈ 2 ATP).

Component of flavins FAD and FMN, used as
cofactors in redox reactions.

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12
Q 
Vitamin B2 (riboflavin)
DEFICIENCY
A

The 2 C’s of B2.

Cheilosis (inflammation of lips, scaling and
fissures at the corners of the mouth), Corneal
vascularization.

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13
Q 
Vitamin B3 (niacin)
FUNCTION
A

NAD derived from Niacin (B3 ≈ 3 ATP).

Derived from tryptophan. Synthesis requires vitamins B2 and B6. Used to treat dyslipidemia.

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14
Q 
Vitamin B3 (niacin)
DEFICIENCY
A

The 3 D’s of B3.

Symptoms of pellagra: Diarrhea, Dementia , Dermatitis (C3/C4 dermatome circumferential “broad collar” rash).

Can be caused by Hartnup disease, malignant carcinoid syndrome (􀁱 tryptophan metabolism), and isoniazid (􀁲 vitamin B6).

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15
Q

Vitamin B3 (niacin)

A

Facial flushing, hyperglycemia, hyperuricemia.

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16
Q

Hartnup disease

A

disease—autosomal recessive. Deficiency of neutral amino acid (eg, tryptophan).
Pellagra-like symptoms. Treat with highprotein diet and nicotinic acid.

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17
Q

Vitamin B5 (pantothenic acid)FUNCTION

A

B5 is “pento”thenic acid.

Essential component of coenzyme A (CoA, a cofactor for acyl transfers) and fatty acid synthase.

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18
Q

Vitamin B5 (pantothenic acid) DEFICIENCY

A

Dermatitis, enteritis, alopecia, adrenal

insufficiency.

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19
Q

Vitamin B6 (pyridoxine) FUNCTION

A

Cofactor used in transamination (eg, ALT and AST),
decarboxylation reactions, glycogen phosphorylase.

Synthesis of cystathionine, heme, niacin, histamine, and neurotransmitters including serotonin, epinephrine, norepinephrine (NE), dopamine, and GABA.

20
Q

Vitamin B6 (pyridoxine) DEFICIENCY

A

Convulsions, hyperirritability, peripheral neuropathy (deficiency inducible by isoniazid and oral contraceptives), sideroblastic anemias due to impaired hemoglobin synthesis and iron excess.

21
Q

Vitamin B7 (biotin)FUNCTION

A

Cofactor for carboxylation enzymes:
􀂃 Pyruvate carboxylase
􀂃 Acetyl-CoA carboxylase
􀂃 Propionyl-CoA carboxylase

22
Q

Vitamin B7 (biotin) DEFICIENCY

A

Rare. Dermatitis, alopecia, enteritis. Caused by antibiotic use

23
Q

Vitamin B9 (folate) FUNCTION

A

Important for the synthesis of nitrogenous bases
in DNA and RNA.

Absorbed in jejunum.

24
Q

Vitamin B9 (folate)DEFICIENCY

A
  • Macrocytic, megaloblastic anemia; hypersegmented
    (PMNs); glossitis; no neurologic symptoms (as opposed to vitamin B12 deficiency).
  • Labs: 􀁱 homocysteine, normal methylmalonic acid
    levels.
  • Seen in alcoholism and pregnancy.
25
Q

Vitamin B12 (cobalamin) FUNCTION

A

Cofactor for methionine synthase and methylmalonyl-CoA mutase. Important for DNA synthesis.

26
Q

Vitamin B12 (cobalamin) DEFICIENCY

A

Macrocytic, megaloblastic anemia; hypersegmented PMNs; paresthesias and subacute combined degeneration due to abnormal myelin.

27
Q 
Vitamin C (ascorbic acid)
FUNCTION
A

Antioxidant; facilitates iron absorption by reducing it to Fe2+ state. Hydroxylation of proline and lysine in collagen synthesis. Necessary for dopamine β-hydroxylase, which converts dopamine to NE.

Ancillary treatment for methemoglobinemia by
reducing Fe3+ to Fe2+.

28
Q 
Vitamin C (ascorbic acid)
DEFICIENCY
A

Vitamin C deficiency causes sCurvy due to a

Collagen synthesis defect.

29
Q

Vitamin C (ascorbic acid) EXCESS

A

Nausea, vomiting, diarrhea, fatigue, calcium oxalate nephrolithiasis.

30
Q

Scurvy

A

Swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages, “corkscrew” hair.

31
Q

Vitamin D FUNCTION

A

intestinal absorption of calcium and phosphate, 􀁱 bone mineralization at low levels, 􀁱 bone resorption at higher levels.

32
Q

Vitamin D DEFICIENCY

A

Rickets in children, osteomalacia in adults, hypocalcemic tetany.

33
Q

Vitamin D EXCESS

A

Hypercalcemia, hypercalciuria, loss of appetite, stupor. Seen in granulomatous disease

34
Q

Vitamin E (tocopherol/tocotrienol) FUNCTION

A

Antioxidant. High-dose supplementation may alter

metabolism of vitamin K 􀁰 enhanced anticoagulant effects of warfarin.

35
Q

Vitamin E (tocopherol/tocotrienol) DEFICIENCY

A

Hemolytic anemia, acanthocytosis, muscle weakness, posterior column and spinocerebellar tract
demyelination.
Aumented serum methylmalonic acid levels.

36
Q

Vitamin K (phytomenadione, phylloquinone, phytonadione) FUNCTION

A

cofactor for the γ-carboxylation of glutamic acid residues. Maturation of clotting factors II, VII, IX,
X, and proteins C and S.

37
Q

Vitamin K (phytomenadione, phylloquinone, phytonadione) DEFICIENCY

A

Neonatal hemorrhage with 􀁱 PT and 􀁱 aPTT but normal bleeding time.

38
Q

Zinc FUNCTION

A

Mineral essential for the activity of 100+ enzymes. Important in the formation of zinc fingers

39
Q

Zinc DEFICIENCY

A

Delayed wound healing, hypogonadism, 􀁲 adult hair (axillary, facial, pubic), dysgeusia, anosmia, acrodermatitis enteropathica.

40
Q

Protein-energy malnutrition

A

Protein malnutrition

41
Q

Kwashiorkor

A

Protein malnutrition

MEALS:
Malnutrition
Edema
Anemia
Liver (fatty)
Skin lesions (hyperkeratosis/ hyperpigmentation)
42
Q

Marasmus

A

Malnutrition not causing edema. Diet is deficient in calories but no nutrients are entirely absent.

43
Q

Fomepizole

A

FOMEpizole—inhibits alcohol dehydrogenase and is an antidote For Overdoses of Methanol or Ethylene glycol.

44
Q

Disulfiram

A

inhibits acetaldehyde dehydrogenase (acetaldehyde accumulates, contributing to hangover symptoms), discouraging drinking.

45
Q

Ethanol metabolism increase NADH/NAD+ ratio in

liver, causing:

A
  • Pyruvate to lactate (lactic acidosis)
  • Oxaloacetate to malate (prevents gluconeogenesis 􀁰 fasting hypoglycemia).
  • Dihydroxyacetone phosphate to glycerol- 3-phosphate (combines with fatty acids to make triglycerides 􀁰 hepatosteatosis).
  • NADH leads to aumented utilization of acetyl-CoA for ketogenesis (􀁰 ketoacidosis) and lipogenesis (􀁰 hepatosteatosis)..

USMLE 1 (73 decks)

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