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Flashcards in vitamins/nutrition Deck (94):
1

fat soluble vitamins

DEAK.
absorption depends on gut (ILEUM) and pancreas.

2

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

DEAK accumulate in fat

3

what causes fat soluble vitamin deficiencies?

1. malabsorption syndromes with steatorrhea (CF, sprue).
2. mineral oil intake.

4

water soluble vitamins

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

5

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

B12 and folate - stored in LIVER

6

B complex deficiencies often result in?

dermatitis.
glossitis.
diarrhea.

7

vitamin A (retinol)

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

8

vitamin A is used as TX for...

1. measles.
2. AML, subtype M3.

9

vitamin A found in...

liver and leafy vegetables (carotene)

10

vitamin A deficiency

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

11

vitamin A excess

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

12

vitamin A teratogenicity

cleft palate, cardiac abn.

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

13

vitamin B1 (thiamine)

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"

14

vitamin B1 deficiency

impaired glucose breakdown = ATP depletion.

1. Wernicke-Korsakoff syndrome.
2. beriberi.

15

what can worsen vitamin B1 deficiency?

glucose infusion (already ATP-depleted)

16

which organs are affected first by vitamin B1 deficiency

highly aerobic tissues - BRAIN, HEART

17

vitamin B1 deficiency is seen in?

1. malnutrition.
2. alcoholism (second to malnutrition and malabsorption).

18

Wernicke-Korsakoff

TRIAD:
1. confusion.
2. ophthalmoplegia.
3. ataxia.

+ confabulation, personality change, memory loss (permanent)

19

brain damage in Wernicke-Korsakoff

medial dorsal nucleus of thalamus
and mammillary bodies

20

dry beriberi

polyneuritis.
symmetrical muscle wasting.

21

wet beriberi

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

22

vitamin B2 (riboflavin)

cofactor in oxidation and reduction (FAD, FMN)

23

vitamin B2: FAD

electron carrier/donor involved in electron transport chain

24

vitamin B2: FMN

part of complex I in ETC

25

vitamin B2 deficiency

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

Corneal vascularization.

"2 C's of B2"

26

vitamin B3 (niacin)

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

27

what is vitamin B3 derived from?

tryptophan

28

what does synth of vitamin B3 require?

vitamin B6

29

vitamin B3 deficiency

glossitis

30

SEVERE vitamin B3 deficiency

PELLAGRA:
Diarrhea,
Dermatitis,
Dementia

31

causes of pellagra

1. Hartnup disease: decreased tryptophan absorp.

2. malignant carcinoid syndrome: increased tryptophan metab.

3. isoniazid tx: decrease vit B6.

32

vitamin B3 excess

facial flushing - due to pharmacologic doses for tx of hyperlipidemia

33

vitamin B5 (pantothenate)

essential component of:
1. coenzyme A (cofactor for acyl transfers)
2. fatty acid synthase

34

vitamin B5 deficiency

dermatitis.
enteritis.
alopecia.
adrenal insuff.
burning feet syndrome.

35

vitamin B6 (pyridoxine)

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

36

vitamin B6 needed in synth of ....?

cystathione.
heme.
niacin.
GABA.
histamine.

37

vitamin B6 deficiency

convulsions.
hyperirritability.
peripheral neuropathy.
sideroblastic anemias*

38

what drugs can induce vitamin B6 deficiency?

isoniazid (B6 analog).
oral contraceptives.

39

pathogenesis of sideroblastic anemia in vitamin B6 deficiency

due to impaired Hb synth and Fe excess

40

vitamin B12 (cobalamin)

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

2. methylmalonyl-CoA mutase.

41

source of vitamin B12

animal products.
can be synthesized only by microorganisms.

42

vitamin B12 deficiency

macrocytic megaloblastic anemia.
hypersegmented PMNs.

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

43

prolonged vitamin B12 deficiency leads to...?

IRREVERSIBLE nervous system damage

44

why does vitamin B12 deficiency takes YEARS to develop?

very large reserve pool stored in LIVER

45

causes of vitamin B12 def

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

etiology of vitamin B12 def determined with..?

Schilling test

47

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

dietary deficiency

48

low excretion in Schilling test needs to be followed with?

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

where is B12 normally absorbed?

terminal ileum
(binds IF in duodenum)

50

TX of B12 def

parental B12
*oral only effective in dietary def

51

folic acid

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

important for synth of nitrogenous bases in DNA and RNA.

52

source of folic acid

green leaves

53

folic acid storage

small reserve pool stored in liver.
lasts 3-4 months beyond dietary def.

54

folic acid def

macrocytic megaloblastic anemia.
NO NEURO SX.

55

what is the most common vit deficiency in US?

folic acid

56

folic acid def common in what conditions?

alcoholism.
pregnancy.

57

supplemental folic acid in preg reduces...?

neural tube defects

58

drugs that cause folic acid def

phenytoin.
sulfonamide.
MTX.
etc.

59

what drugs inhibit conversion of folic acid to THF?

via inhibition of DHFR:
trimethoprim.
MTX.
pyrimethamine.

60

S-adenosyl-methionine (SAM)

formed from ATP + methionine.
transfers methyl groups.

61

regeneration of SAM is dependent on ?

vit B12 and folate - (regeneration of methionine)

62

SAM is required for?

conversion of NE to epinephrine

63

biotin

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

biotin deficiency

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

dermatitis.
enteritis.
alopecia.

65

vitamin C (ascorbic acid)

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

source of vitamin C

fruits and vegetables

67

vitamin C def

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

weakened imm response.

68

pathogenesis of scurvy

vit C def causes collagen synth defect

69

vitamin C excess

nausea.
vomiting.
diarrhea.
fatigue.
sleep problems.

70

vitamin C excess increases risk of iron toxicity in...?

predisposed individuals - transfusions, hereditary hemochromatosis

71

vitamin D2

ergocalciferol: ingested from plants

72

vitamin D3

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

73

storage form of vitamin D

25-OH D3

74

active form of vitamin D

1,25-(OH2) D3 aka calcitriol

75

vitamin D is different from all other vitamins because...?

it can be made in human body

76

vitamin D function

1. increase intestinal absorption of calcium and phosphate.

2. increase bone mineralization.

77

vitamin D def

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

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

78

vitamin D in breast milk

not adequate.
supplement in dark-skinned pts.

79

vitamin D excess

hypercalcemia.
hypercalciuria.
loss of appetite.
stupor.

80

what systemic disease is assoc with vitamin D excess?

sarcoidosis:
increased activation of vitamin D by epithelioid macrophages.

*seen in other granulomatous diseases too

81

vitamin E (tocopherols)

ANTIOXIDANT: protects Erythrocytes and membranes from free radical damage.

*RBCs and neurons

82

vitamin E def

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

vitamin K

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

84

vitamin K synthesized by?

intestinal flora

85

which clotting factors require vitamin K?

II, VII, IX, X.
proteins C and S.

86

what drug is a vitamin K antagonist?

warfarin

87

vitamin K def

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

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

88

why are neonates prone to vitamin K def?

sterile intestines - unable to synthesize vitamin K

89

causes of vitamin K def in adults

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

90

where do neonates get vitamin K when born?

injection given at birth to prevent hemorrhage.

vitamin K not present in breast milk.

91

zinc

essential for activity of 100+ enzymes.

part of zinc fingers (transcription factor motif).

92

zinc def

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

93

zinc def may predispose to ?

alcoholic cirrhosis

94

which vitamins are antioxidants?

A, C, E