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Biochem > vitamins/nutrition > Flashcards

vitamins/nutrition Flashcards

1
Q

fat soluble vitamins

A

DEAK.

absorption depends on gut (ILEUM) and pancreas.

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2
Q

why is toxicity with fat soluble vitamins MORE COMMON than for water-soluble vitamins?

A

DEAK accumulate in fat

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3
Q

what causes fat soluble vitamin deficiencies?

A
  1. malabsorption syndromes with steatorrhea (CF, sprue).

2. mineral oil intake.

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4
Q

water soluble vitamins

A 
B1 thiamine.
B2 riboflavin.
B3 niacin.
B5 pantothenic acid.
B6 pyridoxine.
B12 cobalamin.
C ascorbic acid.
biotin.
folate.
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5
Q

all water soluble vitamins wash out EASILY from body EXCEPT??

A

B12 and folate - stored in LIVER

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6
Q

B complex deficiencies often result in?

A

dermatitis.
glossitis.
diarrhea.

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7
Q

vitamin A (retinol)

A
  1. antioxidant.
  2. visual pigments (retinal).
  3. normal differentiation of epith cells into specialized tissue (pancreatic. mucus-secreting.)
  4. prevent squamous metaplasia.
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8
Q

vitamin A is used as TX for…

A
  1. measles.

2. AML, subtype M3.

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9
Q

vitamin A found in…

A

liver and leafy vegetables (carotene)

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10
Q

vitamin A deficiency

A
  1. night blindness (nyctalopia).
  2. dry skin.
  3. infx (esp measles).
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11
Q

vitamin A excess

A
  1. arthralgias.
  2. fatigue.
  3. headache.
  4. skin changes
  5. alopecia.
  6. sore throat.
  7. teratogenic.
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12
Q

vitamin A teratogenicity

A

cleft palate, cardiac abn.

preg test must be done before isotretinoin prescribed for severe acne.

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13
Q

vitamin B1 (thiamine)

A

part of thiamine pyrophosphate (TPP), a cofactor for decarboxylation rxns:

  1. Pyruvate dehydrogenase (glycolysis).
  2. Alpha-ketoglutarate dehydrogenase (TCA).
  3. Transketolase (HMP).
  4. branched chain AA dehydrogenase.

“A, T, P needed for ATP synth”

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14
Q

vitamin B1 deficiency

A

impaired glucose breakdown = ATP depletion.

  1. Wernicke-Korsakoff syndrome.
  2. beriberi.
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15
Q

what can worsen vitamin B1 deficiency?

A

glucose infusion (already ATP-depleted)

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16
Q

which organs are affected first by vitamin B1 deficiency

A

highly aerobic tissues - BRAIN, HEART

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17
Q

vitamin B1 deficiency is seen in?

A
  1. malnutrition.

2. alcoholism (second to malnutrition and malabsorption).

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18
Q

Wernicke-Korsakoff

A

TRIAD:

  1. confusion.
  2. ophthalmoplegia.
  3. ataxia.

+ confabulation, personality change, memory loss (permanent)

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19
Q

brain damage in Wernicke-Korsakoff

A

medial dorsal nucleus of thalamus

and mammillary bodies

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20
Q

dry beriberi

A

polyneuritis.

symmetrical muscle wasting.

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21
Q

wet beriberi

A

high-output cardiac failure (dilated CM).
edema.
neuropathy.

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22
Q

vitamin B2 (riboflavin)

A

cofactor in oxidation and reduction (FAD, FMN)

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23
Q

vitamin B2: FAD

A

electron carrier/donor involved in electron transport chain

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24
Q

vitamin B2: FMN

A

part of complex I in ETC

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25
Q

vitamin B2 deficiency

A

Cheilosis: inflamm of lips, scaling and fissures at corners of mouth.

Corneal vascularization.

“2 C’s of B2”

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26
Q

vitamin B3 (niacin)

A

constituent of NAD+ and NADP+ used in redox runs.

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27
Q

what is vitamin B3 derived from?

A

tryptophan

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28
Q

what does synth of vitamin B3 require?

A

vitamin B6

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29
Q

vitamin B3 deficiency

A

glossitis

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30
Q

SEVERE vitamin B3 deficiency

A

PELLAGRA:
Diarrhea,
Dermatitis,
Dementia

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31
Q

causes of pellagra

A
  1. Hartnup disease: decreased tryptophan absorp.
  2. malignant carcinoid syndrome: increased tryptophan metab.
  3. isoniazid tx: decrease vit B6.
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32
Q

vitamin B3 excess

A

facial flushing - due to pharmacologic doses for tx of hyperlipidemia

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33
Q

vitamin B5 (pantothenate)

A

essential component of:

  1. coenzyme A (cofactor for acyl transfers)
  2. fatty acid synthase
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34
Q

vitamin B5 deficiency

A 
dermatitis.
enteritis.
alopecia.
adrenal insuff.
burning feet syndrome.
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35
Q

vitamin B6 (pyridoxine)

A

converted to pyridoxal phosphate: cofactor in transamination, decarboxylation, glycogen phosphorylase

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36
Q

vitamin B6 needed in synth of ….?

A 
cystathione.
heme.
niacin.
GABA.
histamine.
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37
Q

vitamin B6 deficiency

A

convulsions.
hyperirritability.
peripheral neuropathy.
sideroblastic anemias*

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38
Q

what drugs can induce vitamin B6 deficiency?

A

isoniazid (B6 analog).

oral contraceptives.

39
Q

pathogenesis of sideroblastic anemia in vitamin B6 deficiency

A

due to impaired Hb synth and Fe excess

40
Q

vitamin B12 (cobalamin)

A

cofactor for:
1. homocysteine methyltransferase: transfer CH3 group as methylcobalamin.

  1. methylmalonyl-CoA mutase.
41
Q

source of vitamin B12

A

animal products.

can be synthesized only by microorganisms.

42
Q

vitamin B12 deficiency

A

macrocytic megaloblastic anemia.
hypersegmented PMNs.

neuro sx: paresthesias. subacute combined degeneration. *due to abn myelin

43
Q

prolonged vitamin B12 deficiency leads to…?

A

IRREVERSIBLE nervous system damage

44
Q

why does vitamin B12 deficiency takes YEARS to develop?

A

very large reserve pool stored in LIVER

45
Q

causes of vitamin B12 def

A
  1. malabsorption: sprue, enteritis, pancreatic insuff, Diphyllobothrium latum.
  2. lack of intrinsic factor: pernicious anemia, gastric bypass.
  3. absence of terminal ileum: Crohn’s dz.
46
Q

etiology of vitamin B12 def determined with..?

A

Schilling test

47
Q

normal urinary (radiolabeled) B12 excretion in Schilling test indicates?

A

dietary deficiency

48
Q

low excretion in Schilling test needs to be followed with?

A

repeat test with addition of intrinsic factor- if excretion is then corrected, deficiency is due to pernicious anema/atrophic gastritis.

if excretion still low- deficiency due to malabsorption.

49
Q

where is B12 normally absorbed?

A 
terminal ileum 
(binds IF in duodenum)
50
Q

TX of B12 def

A

parental B12

*oral only effective in dietary def

51
Q

folic acid

A

converted to THF, a coenzyme for 1-carbon transfer/methylation rxns.

important for synth of nitrogenous bases in DNA and RNA.

52
Q

source of folic acid

A

green leaves

53
Q

folic acid storage

A

small reserve pool stored in liver.

lasts 3-4 months beyond dietary def.

54
Q

folic acid def

A

macrocytic megaloblastic anemia.

NO NEURO SX.

55
Q

what is the most common vit deficiency in US?

A

folic acid

56
Q

folic acid def common in what conditions?

A

alcoholism.

pregnancy.

57
Q

supplemental folic acid in preg reduces…?

A

neural tube defects

58
Q

drugs that cause folic acid def

A

phenytoin.
sulfonamide.
MTX.
etc.

59
Q

what drugs inhibit conversion of folic acid to THF?

A

via inhibition of DHFR:
trimethoprim.
MTX.
pyrimethamine.

60
Q

S-adenosyl-methionine (SAM)

A

formed from ATP + methionine.

transfers methyl groups.

61
Q

regeneration of SAM is dependent on ?

A

vit B12 and folate - (regeneration of methionine)

62
Q

SAM is required for?

A

conversion of NE to epinephrine

63
Q

biotin

A

cofactor for carboxylation enzymes, which add 1-carbon group.

  1. pyruvate carboxylase.
  2. acetyl CoA carboxylase.
  3. propionyl CoA carboxylase.
  4. beta-methylcrotonyl CoA carboxylase.
64
Q

biotin deficiency

A

relatively rare.
caused by Abx or excessive ingestion of raw egg whites.

dermatitis.
enteritis.
alopecia.

65
Q

vitamin C (ascorbic acid)

A
  1. antioxidant.
  2. keeps iron in Fe2+ reduced state for absorption.
  3. hydroxylation of proline and lysine in collagen synth.
  4. dopamine beta-hydroxylase (dopamine to NE).
66
Q

source of vitamin C

A

fruits and vegetables

67
Q

vitamin C def

A 
SCURVY: 
swollen gums.
bruising.
hemarthrosis.
anemia.
poor wound healing.

weakened imm response.

68
Q

pathogenesis of scurvy

A

vit C def causes collagen synth defect

69
Q

vitamin C excess

A 
nausea.
vomiting.
diarrhea.
fatigue.
sleep problems.
70
Q

vitamin C excess increases risk of iron toxicity in…?

A

predisposed individuals - transfusions, hereditary hemochromatosis

71
Q

vitamin D2

A

ergocalciferol: ingested from plants

72
Q

vitamin D3

A

cholecalciferol: consumed in milk, formed in sun-exposed skin

73
Q

storage form of vitamin D

A

25-OH D3

74
Q

active form of vitamin D

A

1,25-(OH2) D3 aka calcitriol

75
Q

vitamin D is different from all other vitamins because…?

A

it can be made in human body

76
Q

vitamin D function

A
  1. increase intestinal absorption of calcium and phosphate.

2. increase bone mineralization.

77
Q

vitamin D def

A

kids: rickets (bending bones).
adults: osteomalacia (soft bones).

hypocalcemic tetany.
skeletal deformities.
bone pain.
muscle weakness.

78
Q

vitamin D in breast milk

A

not adequate.

supplement in dark-skinned pts.

79
Q

vitamin D excess

A

hypercalcemia.
hypercalciuria.
loss of appetite.
stupor.

80
Q

what systemic disease is assoc with vitamin D excess?

A

sarcoidosis:
increased activation of vitamin D by epithelioid macrophages.

*seen in other granulomatous diseases too

81
Q

vitamin E (tocopherols)

A

ANTIOXIDANT: protects Erythrocytes and membranes from free radical damage.

*RBCs and neurons

82
Q

vitamin E def

A

increase RBC fragility - hemolytic anemia.

muscle weakness.
dorsal (posterior) column
and spinocerebellar tract demyelination
(aka subacute combined degeneration of SC).
SX: loss of proprioception, vibration. ataxia.

83
Q

vitamin K

A

catalyzes gamma-carboxylation of glutamic acid residues on certain proteins concerned with BLOOD CLOTTING

84
Q

vitamin K synthesized by?

A

intestinal flora

85
Q

which clotting factors require vitamin K?

A

II, VII, IX, X.

proteins C and S.

86
Q

what drug is a vitamin K antagonist?

A

warfarin

87
Q

vitamin K def

A

neonatal hemorrhage with increased PT and increased PTT but NORMAL bleeding time.

SX: tendency to bleed.
skin, umbilicus, viscera, brain.

88
Q

why are neonates prone to vitamin K def?

A

sterile intestines - unable to synthesize vitamin K

89
Q

causes of vitamin K def in adults

A

prolonged use of broad-spectrum Abx.
malabsorption syndromes.
generalized liver disease.

90
Q

where do neonates get vitamin K when born?

A

injection given at birth to prevent hemorrhage.

vitamin K not present in breast milk.

91
Q

zinc

A

essential for activity of 100+ enzymes.

part of zinc fingers (transcription factor motif).

92
Q

zinc def

A 
delayed wound healing.
hypogonadism.
decreased adult hair.
anosmia (lack of smell).
dysgeusia (abn taste).
93
Q

zinc def may predispose to ?

A

alcoholic cirrhosis

94
Q

which vitamins are antioxidants?

A

A, C, E

Biochem (7 decks)

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