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BMS15 > Vitamins 1 > Flashcards

Vitamins 1 Flashcards

Intro and B vitamins

1
Q

What is a vitamin?

A

Complex organic substance required in diet in small amounts compared to other dietary components

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2
Q

Where are “fat-soluble factors” found and what vitamins do they contain?

A

Butter and egg yolk

A D E

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3
Q

Where are “heat-labile factors” found and what vitamins do they contain?

A

Wheat germ

B C

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4
Q

Which vitamins are water-soluble?

A

B

C

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5
Q

Which vitamins are fat-soluble?

A

A

D

E

K

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6
Q

Describe the differences between fat- and water-soluble vitamins.

A

Fat - stored (not absorbed and excreted easily) and deficiency symptoms show after a year; may be toxic in excess

Water - not stored extensively (lost in urine) and deficiency symptoms show after three months; generally not toxic in excess

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7
Q

What type of vitamin must be taken frequently?

A

Water-soluble (B, C)

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8
Q

What is a primary deficiency?

A

Deficiency caused by not taking enough of the vitamin (eg. in diet)

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9
Q

What is a secondary deficiency?

A

Deficiency caused by another factor preventing the absorption/activation/functioning of a vitamin

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10
Q

What is the general role of the B vitamins?

A

Act as coenzymes in metabolic pathways

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11
Q

What is the name of vitamin B1?

A

Thiamin

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12
Q

Which vitamin is thiamin?

A

B1

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13
Q

In what type of diets is beri-beri especially found?

A

Mainly carbohydrates (polished white rice)

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14
Q

Why may alcoholics have vitamin deficiencies? (3)

A

“Empty calories” from alcohol give adequate energy intake so do not eat a variety of foods and may be anorexic

GI tract malfunctions common = malabsorption

Cirrhotic liver affects storage, transport and metabolism of many vitamins (esp. A)

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15
Q

Why is “Wernicke-Korsakoff” syndrome mainly associated with alcoholism?

A

Vitamin B1/thiamin defiency

Alcohol inhibits B1 absorption in small intestine and inhibits the enzyme which converts B1 to its active form

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16
Q

What is another term for cerebral beri-beri?

A

Wernicke’s encephalopathy

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17
Q

What are the symptoms of Wernicke’s encephalopathy? (4)

A

Confusion

Ataxia

Polyneuropathy

Disorientation in space and time

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18
Q

If untreated, what does cerebral beri-beri progress to?

A

Korsakoff’s psychosis

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19
Q

What is the main characteristic of Korsakoff’s psychosis?

A

Loss of memory of recent events

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20
Q

What is the difference between dry and wet beri-beri?

A

Dry = no oedema

Wet = oedema

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21
Q

What are the symptoms of wet beri-beri?

A

Oedema

Heart failure

Enlarged heart and liver

Engorged neck veins

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22
Q

What are the symptoms of dry beri-beri? (4)

A

Symmetrical ascending peripheral neuropathy

Weakness and numbness

Ataxic gait

Painful extremities

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23
Q

What are good sources of thiamin? (6)

A

Whole grain

Pork

Poultry

Fish

Vegetables

Dairy produce

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24
Q

What foods are deficient in thiamin? (4)

A

Polished rice

Sugar

Fat

Refined and processed foods

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25
Q

What effect does eating raw fish have on thiamin?

A

Contains thiaminases

Breaks down B1

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26
Q

Are coffee and tea good sources of thiamin and why?

A

No

Contain anti-thiamin factors

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27
Q

Why is thiamin important?

A

Role as thiamin pyrophosphate in conversion of pyruvate to acetyl CoA

Lack = build up of lactate and fatigue

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28
Q

Which vitamin is riboflavin?

A

B2

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29
Q

What is the name of vitamin B2?

A

Riboflavin

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30
Q

What colour is riboflavin?

A

Bright yellow

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31
Q

Where is B2 found? (2)

A

Mainly in milk

Associated with protein

32
Q

Why is riboflavin important?

A

Role as FAD and FMN in redox reactions

33
Q

What population may have B2 deficiencies?

A

Alcoholics

34
Q

Why should you keep riboflavin out of sunlight?

A

UV sensitive

Keep out of sunlight for stability

35
Q

Which vitamin is niacin?

A

B3

36
Q

What is the name of B3?

A

Niacin/nicotinic acid

37
Q

What are vitamers?

A

Different structural forms of a vitamin

38
Q

What is the vitamer of B3?

A

Nicotinamide

39
Q

What are good sources of niacin? (2)

A

High protein diets (formed from tryptophan)

Present in cereals/maize in small amounts

40
Q

Why is niacin important in the body?

A

Role as NAD and NADP in redox reactions

Used to repair UV damage of DNA

41
Q

What is the name of the B3 deficiency?

A

Pellagra

42
Q

What is Pellagra?

A

Niacin/B3 deficiency

43
Q

What are the characteristics of Pellagra?

A

DDD:

  • Dermatitis photosensitive (Casal’s necklace)
  • Diarrhoea
  • Dementia
44
Q

What vitamin deficiency is Casal’s necklace associated with?

A

Niacin/B3 - Pellagra

45
Q

What is the name of vitamin B6?

A

Pyridoxine

46
Q

Which vitamin is pyridoxine?

A

B6

47
Q

Why is B6 important in the body?

A

Role as pyridoxal phosphate which is essential for amino acid metabolism and haem synthesis

48
Q

What is the common type of deficiency of pyridoxine?

A

Secondary/due to antagonists

49
Q

Why are vitamin B6 supplements given when treating some tuberculosis patients?

A

Isoniazid used in treatment of tuberculosis combines with pyridoxal phosphate and renders it unavailable

50
Q

What is a characteristic of pyridoxine deficiency?

A

Seizures

51
Q

What is considered an overdose of pyridoxine and what are the complications?

A

Self medication for premenstrual tension syndrome of 500-5000mg/day

Peripheral neuropathy within 1-3 years

52
Q

What vitamin is often associated with folate?

A

B12/cobalamin

53
Q

What is the name of vitamin B12?

A

Cobalamin

54
Q

Which vitamin is cobalamin?

A

B12

55
Q

What is the role of folate in the body?

A

Carrier of 1C groups as tetrahydrofolate

56
Q

What is the role of cobalamin in the body?

A

Carrier of methyl groups in mammalian metabolism

Allows THF to be freed from non-interconvertible methyl

57
Q

What enzyme is important in the maintenance of THF?

A

Dihydrofolate reductase

58
Q

What is the best source of folate and B12?

A

Liver

59
Q

Where is folate found? (3)

A

Green vegetables

Liver

Whole grains

60
Q

Where is cobalamin found?

A

Animal tissues only

61
Q

What must be present for the absorption of cobalamin in the small intestine?

A

Intrinsic factor

62
Q

How are folate and cobalamin used in the body?

A

Folate converted to tetrahydrofolate and enters pool of 1C-THF derivatives

B12 takes methyl (from THF) to combine with homocysteine to form methionine with B12-dependent methionine synthetase

1C derivatives required in formation of nucleotides and amino acids

63
Q

What is the “B12 trap” and its symptoms? (3)

A

Deficiency in B12 affects folate of normal levels in diet - functional THF deficiency resulting in large immature erythrocytes

Megaloblastosis (giant germ cells)

Haematopoietic cells die in bone marrow

64
Q

What does methotrexate do and what is it used to treat?

A

Inhibits DHF reductase so no THF and no nucleotides formed = no cell division

Treats tumours

65
Q

How does a B12 deficiency affect the nervous system?

A

Causes inadequate myelin synthesis:

  • Numbness
  • Tingling hands and feet
  • Loss of position sense
  • Unsteadiness, ataxia, confusion, moodiness, depression
  • Spinal cord, brain and peripheral nerve lesions
66
Q

How does a folate deficiency affect a foetus?

A

Neural tube defects - anencephaly, spinabifida, encephalocele

67
Q

Which vitamin is pantothenic acid?

A

B5

68
Q

What is the name of vitamin B5?

A

Pantothenic acid

69
Q

Are pantothenic acid deficiencies common and why?

A

No

Found in most foods

70
Q

Why is vitamin B5 important?

A

Component of coenzyme A in metabolism and transfer of carbon

71
Q

Which vitamin is biotin?

A

B7

72
Q

What is the name of vitamin B7?

A

Biotin

73
Q

Why is biotin important?

A

Prosthetic group for carboxylations (eg. pyruvate to oxaloacetate; acetyl CoA to malonyl CoA)

74
Q

What is the main source of vitamin B7?

A

Intestinal bacteria synthesis

75
Q

When do you get biotin deficiencies and why? (2)

A

Eating raw egg whites - contains substances which bind biotin

Long-term antibiotic therapy (1+ years) - sterilisation of abdominal tract

BMS15 (4 decks)

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