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CMBM exam 3 > Micronutrients II - Vitamins > Flashcards

Micronutrients II - Vitamins Flashcards

0
Q

Which vitamins are most utilized in energy metabolism?

A

B vitamins

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1
Q

Vitamins

A

typically cofactors for enzymes
organic compounds required for diet in only small amounts to maintain fundamental cell functions
not catabolized
Organic

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2
Q

how many water soluble vitamins?

A

9

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3
Q

how many lipid soluble vitamins?

A

4

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4
Q

Vitamin-like compounds

A

Inositol
Choline
Lipoic Acid
PQQ-Pyrroloquinoline quinone

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5
Q

Inositol

A

phospholipids

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6
Q

Choline

A

in phospholipids, methyl donor

choline free diet could lead to liver damage

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7
Q

Lipoic Acid

A

not a vitamin but required for pyruvate decarboxylase

animals can make this

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8
Q

PQQ-pyrroloquinoline quinone

A

methoxatin
redox cofactor for quinoproteins
ex: flavoproteins - dehydrogenases

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9
Q

Vitamin D only needed when

A

sunlight is absent

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10
Q

Primary deficiency

A

lack of adequate intake in diet

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11
Q

causes of Primary deficiency

A

poor nutrition/food habits, poverty, ignorance of nutrition needs, insufficient food, lack of proper vitamin rich foods, food fads, food taboos, vitamin destruction, anorexia

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12
Q

Secondary deficiency

A

poor availability or utilization of a vitamin due to environmental or physiological conditions

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13
Q

Causes of secondary deficiency

A 
poor digestions (achlorhydria-low gastric acid) 
malabsorption (diarrhea, infections) 
impaired utilization (drug therapy)
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14
Q

Vitamin deficiencies significant in

A

any pt with digestion/malabsorption problems
chronic substance abuse (alcohol) bad diet & inhibits uptake of vit
recent surgery, total parenteral nutrition
elderly, pregnant/breastfeeding, smokers, alcoholics, diabetics
risk thiamine deficiency with high CHO diet

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15
Q

What aids in fat soluble vitamin absorption?

A

Bile

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16
Q

digestive enzymes from pancreas help uptake

A

vitamin K

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17
Q

Bacteria in the gut make small amount of

A

vitamin K, B12, and biotin

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18
Q

Fat soluble vitamins are absorbed with

A

dietary fat

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19
Q

where are fat soluble vitamins stored?

A

liver and nonspecifically adipose tissue

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20
Q

Risk of toxicity with what vitamin?

A

B vitamins

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21
Q

Vitamin A

A

mixture of Retinoids
role in gene regulation - reproduction, embryogenesis, development, cell differentiation and proliferation) vision, maintenance of brain function and skin

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22
Q

Vitamin A deficiency

A

night blindness

hyperkeratosis

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23
Q

Vitamin A Excess

A

birth defects, (tetratogenic), blurred vision, liver damage

Osteoporosis, hypercalcemia

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24
Q

Vitamin A is derived from

A

carotenoids
plant pigments
b-carotene
-three forms - alcohol, aldehyde and acid

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25
Q

Find Vitamin A in

A

green, leafy vegetables
colored veggies
organ meat - liver

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26
Q

Why is beta carotene a safer source?

A

conversion to Vit A in gut decreases as dose increases

Absorption depends on type of food and how much fat is also in diet

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27
Q

How is Vitamin A taken up?

A

Retinol and carotenoids bound in enterocyte to Carotene binding proteins
carried in blood by chylomicrons or albumin

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28
Q

How is vitamin A important for vision?

A

combines with opsin to form rhodoposin in rod and cone cells
impt for the shape and structure of the conjunctiva and the cornea as well
functions in cellular differentiation - RXR and RAR receptors

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29
Q

Xerophthalmia

A

damage to cornea

can occur with vitamin A deficiency

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30
Q

Accutane

A

oral vitamin A treatment for acne
not for pts who can get pregnant
causes birth defects

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31
Q

Excess Vitamin A

A 
headache 
nausea 
skin irritation 
pain in joints 
Osteoporosis
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32
Q

RAE

A

retinol activity units

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33
Q

Vitamin A RDA

A

men - 900ug/day

women - 700ug/day

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34
Q

what are some world wide problems seen with Vitamin A deficiencies?

A

increased susceptibility to infection
blinds nearly 500,000 preschool aged children
worsens iron status, causing anemia
accompanies protein and Zinc malnutrition
chronic fat malabsorption, low fat intake

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35
Q

Rickets

A

in children
severe bone deforming disease from lack of Vitamin D
cured with sunlight/fish oil

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36
Q

Vitamin D

A

mixture of ergocalciferol (D2) and cholecalciferol (D3)

derived from cholesterol - synthesized in the skin

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37
Q

What is active form?

A

Calcitrol (1,25-dihyroxyvitamin D
liver converts D3 to 25-hydroxyvitamin D
then kidneys converts to 1,25-dihyroxyvitamin D

38
Q

Function of Vitamin D

A

regulates Ca levels in body
increases Ca uptake from diet, decreases Ca loss in uring , facilitates release of Ca from bones
may also modulate inflammation/immune responses

39
Q

Osteomalacia

A

Vit D deficiency in adults

40
Q

Vitamin D RDA

A

10ug/day (about 2 liters of vit D fortified milk

41
Q

Vitamin D excess

A

large excess can be lethal
leads to hypercalcemia - deposition of Ca in soft tissues)
there can be local tissue intoxication

42
Q

Vitamin D deficiencies linked to

A

Type II diabetes, autoimmune disease and other chronic diseases - cardiovascular, cancer

43
Q

Serum level of Vit D deficiency

A

less than 20 ng/mL

44
Q

Vitamin K

A

group of 3 molecules
phylloquinones
k1 - phllyoquinone in green leafy veggies
k2 - menaquinone, made by bacteria in intestines
k3 - menadione, artificial

45
Q

Functions of Vitamin K

A

required for post-translational modification of many proteins which bind Ca++ including blood coagulating proteins
cofactor for carboxylases which add gamma-carboxy group onto glutamates

46
Q

vitamin K inhibitors

A

coumarin/warfarin

inhibit clotting

47
Q

Coumarin

A

in low doses inhibits vitamin k epoxide reductase and vit K reductase
so depletes Vit K and inhibits enzymes requiring vit K
all these inhibited activities lead to blood clotting

49
Q

Name the B vitamins

A 
Thiamine (b1) 
Riboflavin (b2) 
Niacin (b3)
Pantothenic acid (B5) 
Pyridoxine (pyridoxal, pyridoxamine) (b6) 
Biotin (vitamin H) 
Cobalamin (b12) 
Folic acid
50
Q

Thiamine functions

A

helps form/break C-C bonds

  1. Oxidative decarboxylation - pyruvate and a-ketoglutarate DH
  2. Transketolase in PPP - converts glucose to ribose for DNA synthesis
51
Q

Thiamine deficiency

A 
Beriberi
Insufficient ATP production, decreased synthesis of DNA, RNA, proteins, fatty acids 
muscle tissue wasting 
cardiovascular damage 
CNS damage - confusion, loss of reflex 
Edema 
seen in chronic alcoholism 
usually see in skin first
52
Q

Wernicke syndrome

A

Thiamine deficiency
associated with chronic alcoholism
known as dry beriberi becomes wet when develop cardiac dilated hypermyopathy (loss of energy, fluid build up)

53
Q

Severe Thiamine deficiency leads to

A

involves CNS
called Korsakoff encephalopathy (Wernicke-korsakoff syndrome) - leads to short term memory loss
irreversible

54
Q

What predisposes people to WK syndrome when diet is thiamine deficient ?

A

mutation in transketolase

55
Q

Riboflavin

A 
heat stable but light sensitive 
intense yellow-green fluorescence 
Coenzyme in TCA cycle - FAD/FADH 
cofactor for other enzymes, oxygenases, oxidoreductases 
can carry 2 electrons 
can store about 1-2 weeks worth
56
Q

what inhibits Thiamine uptake?

A

Alcohol

57
Q

Riboflavin deficiency

A

prolonged can lead to cracked lips, dark red tongue, dermatitis, normocytic anemia, confusion

58
Q

Excess Riboflavin

A

no real effect

lost rapidly

59
Q

Forms of Niacin

A 
nicotinic acid (precursor to NAD and NADP) and nicotinamide 
Active form is NAD (bound to ribose and ADP)
60
Q

Niacin deficiency

A

Pellagra -fragile skin called Casal’s necklace
corn is low in niacin and Trp
fatigue, headache, apathy, depression, memory loss, dementia, pigmented skin rash after sun exposure, vomiting, diarrhea

61
Q

Trp metabolite in urine suggests deficiency in

A

Niacin

62
Q

Niacin Equivalents NE

A

1 mg pure niacin or 60 mg trytophan
Men 16 mg NE/day
women 14

63
Q

Hartnup disease

A

impairs Trp absorption can lead to niacin deficiency

64
Q

Excess Niacin

A

Flushing, buring of face, arms and chest, stomach irritation
long term - liver damage, irreversible liver failure

65
Q

Excess of what vitamin could be cholesterol lowering ?

A

Niacin
must be watched carefully though
acts via G protein coupled receptor, reduces lipolysis, free fatty acids, VLDLs

66
Q

Pantothenic acid

A

component of CoA and acyl carrier protein
No RDA, no deficiencies, excess seen
hard to differentiate Pantothenate deficiency from other vit B deficiencies - skin problems, burning feet, digestive problems, dizziness

67
Q

Pyridoxine

A

involved in transamination, decarboxylation

required for function of glycogen phosphorylase, synthesis of heme, y-aminobutyric acid

68
Q

Pyridoxal Phosphate (PLP)

A

derived from B6
deficiency leads to dermatitis and disorders of protein metabolism
group for enzymes catalyzing reactions involving amino acid metabolism

69
Q

Pyridoxine deficiencies

A

microcytic anemia, EEG abnormalites, epileptic seizures, depression, confusion, seborrheic dermatitis, maybe also platelet and clotting problems

70
Q

Drugs that can create a PLP deficiency

A

penicillinamine or isozianid

71
Q

Pyridoxine excess

A

peripheral neuropathy, derm lesions

72
Q

Biotin

A

synthesized by gut bacteria
tightly binds to egg protein (avidin)
functions in carboxylase reactions in FA synthesis, essential for lipid metabolism, amino acid breakdown

73
Q

Biotin deficiency

A

impaired glucose tolerance, mental dysfunction, nausea, anorexia, dermatitis
some anticonvulsants inhibit uptake

74
Q

Cyanocobalamin - vit B12

A

conenzymes: methylcobalamin, adenosylcobalamin
most potent - 3ug/day
contains corrin ring system and a cobalt
only synthesized by some bacteria
participates in enzyme catalyzed molecular rearrangements, ribonucleotide reductase and methyl group transfers
regenerates FH4 from methyl folate, prevents folate deficiency

75
Q

Vitamin B12 deficiency

A
  • can cause long tern, permanent damage to myelin sheath, peripheral neuropathy
  • Pernicious anemia - megaloblastic anemia due to lack of intrinsic factor secretion
  • lead to elevated homocysteine levels which are linked to CVD due to interference with collagen maturation
76
Q

B12 and folate

A

intimate interaction with folate
levels fall with folate
anemia, temporarily respond to folate tx masking the deficiency but has neuro consequences

77
Q

B12 deficiency most common in

A

wealthier countries, among elderly, most prevalent in poorer populations

78
Q

Metformin

A

impairs B12 uptake

79
Q

Diagnosis of B12 deficiency

A

serum or plasma ~200 pg/ml

80
Q

Excess B12

A

doesnt hurt

81
Q

what deficiencies increase serum tHcy

A 
folate 
riboflavin 
vitamin B6 
B12
THF
82
Q

Homocysteine

A

remove terminal Ch3 from methionine

83
Q

conversion of homocysteine to Methionine

A

Tetrahydrofolate and B12

84
Q

conversion of homocysteine to Cys

A

B6

85
Q

Intrinsic Factor

A

secreted from parietal cells in response to hormone
B12 ONLY absorbed in intestines when complexed to IF
binds to specific receptor in the ileum

86
Q

Pernicious anemia

A

megaloblastic anemia due to lack of intrinsic factor secretion
atrophy of mucosa, loss of secretion of gastric acid and IF

87
Q

Liver stores B12 can last

A

6-10years

88
Q

Folate

A

FH4 made from folate
major carrier of single carbon units
takes 1C from Ser, Gly, His, formaldehyde and formate
1C transferred to pyrimidine dUMP to form dTMP - vital for DNA synthesis
cooking destroys 90% in food

89
Q

Folate deficiency

A

affects rapidly dividing cells - RBC, intestinal epithelium, fetal tissues
Fetal - neural tube defects

90
Q

Megaloblastic anemia

A

caused by both folate and cobalamine deficiencies
due to thymidylate synthase deficiency
causes enlarged red and white blood cells - abnormal nuclear maturation - NOT enough DNA

91
Q

oral contraceptives and anticonvulsants

A

impair absorption or increase the breakdown of folate

92
Q

Single carbon transfers

A

THF transfers CH3 to B12 which adds that too Homocysteine to make methionine

93
Q

Vitamins stored in the liver

A

B12

Folate

CMBM exam 3 (24 decks)

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