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BMS15 > Vitamins 2 > Flashcards

Vitamins 2 Flashcards

Not including B vitamins

1
Q

What is the name of vitamin C?

A

Ascorbic acid

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2
Q

Which vitamin is ascorbic acid?

A

C

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3
Q

What are the biochemical roles of vitamin C? (2)

A

Antioxidant - protect vitamins A, E and K from oxidation

Required to maintain reduced Fe (II) form for proline and lysine hydroxylase activity in collagen formation

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4
Q

What is scurvy and its symptoms?

A

Vitamin C deficiency

Impaired wound healing, haemorrhages, anaemia, poor collagen, joint pain

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5
Q

How long will the store of vitamin C in a well-fed human last?

A

6 months but scurvy symptoms will appear after 3 months

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6
Q

What population groups have low levels of vitamin C?

A

Elderly

Alcoholics

Adolescents on ‘junk’ food

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7
Q

What is the normal daily recommending intake of vitamin C?

A

40mg/day

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8
Q

How much vitamin C do smokers need compared to normal people and why?

A

Twice as much (80mg/day)

Turnover is greatly increased by smoking

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9
Q

What are the risks of megadoses of vitamin C? (3)

A

Oxalate kidney stones

Diarrhoea

Systemic conditioning which increases likelihood of deficiency

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10
Q

What type of deficiency is more common with fat-soluble vitamins?

A

Primary

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11
Q

Why do developed countries have more secondary deficiencies of fat-soluble vitamins?

A

Low fat diets

Fat malabsorption

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12
Q

Which vitamin is retinol?

A

A

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13
Q

What are the sources of retinol? (4)

A

Animal Liver

Fish liver oil

Whole milk

Egg yolk

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14
Q

What are the sources of plant carotenoids?

A

Green, yellow, orange vegetables and fruit

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15
Q

Which (inactive) form of vitamin A is more important/efficient?

A

Retinol

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16
Q

How much more carotenoid must be eaten to get the equivalent of one retinol?

A

Six times

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17
Q

What is 1RE?

A

1 retinol equivalent - expresses potency (1ug of retinol)

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18
Q

What are the active forms of vitamin A?

A

Retinoic acid

Retinal

β-carotene

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19
Q

What is the function of retinoic acid?

A

Acts similarly to steroid hormones to affect protein synthesis in growth and differentiation

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20
Q

What is retinoic acid used to treat?

A

Acne

21
Q

What is the function of retinal?

A

At low light intensity (scotopic vision), 11-cis retinal participates in conversion of light energy to impulses in optic nerve in rod cells of retina

22
Q

What is the function of β-carotene?

A

Antioxidant

23
Q

How is vitamin A transported?

A

In chylomicrons from gut to liver

From liver to tissues bound to specific retinol-binding proteins and prealbumin

24
Q

What is the usual cause of retinol deficiency and why?

A

Inadequate protein diets

Affects synthesis of retinol-binding proteins and therefore transport to tissues

25
Q

How will a vitamin A deficiency affect vision? (3)

A

Night blindness

Followed by progressive keratinisation of cornea/xerophthalmia

Finally keratomalacia and irreversible blindness (role in epithelial cell function and mucopolysaccharide synthesis)

26
Q

What are the symptoms of too much vitamin A? (4)

A

Dermatitis

Hair loss

Hepatic dysfunction

Thinning and fracture of long bones

27
Q

Which vitamin can be absorbed through the skin?

A

Vitamin E

28
Q

What are the sources of vitamin E? (3)

A

Vegetable oils (esp. wheat germ oil)

Green vegetables

Nuts

29
Q

What is the most potent tocopherol?

A

α-tocopherol

30
Q

What type of vitamin includes the tocopherol family?

A

E

31
Q

What is a safe dose of vitamin E?

A

Up to 1g/day

32
Q

What is the function of vitamin E? (4)

A

Prevents oxidation of unsaturated/polyunsaturated fatty acids in cell membranes and circulating lipoproteins by free radical attack

Reaction of free radicals with vitamin E/antioxidant terminates chain reactions

Maintains cell membrane structure and cell integrity

Some PUFAs are prostaglandin precursors

33
Q

What would be formed from a reaction between a fatty acid radical and oxygen?

A

Peroxyl radical

34
Q

How does a vitamin E deficiency affect animals (not humans)?

A

Sterility

Muscular dystrophy

35
Q

How does a vitamin E deficiency affect humans?

A

Unknown except in premature, low birth weight babies - haemolytic anaemia

36
Q

Which vitamins do not cross the placenta easily?

A

E

K

37
Q

What are the two D vitamins?

A

Cholecalciferol D3

Ergocalciferol D2

38
Q

How is cholecalciferol formed?

A

Reaction of UV light and 7-dehydrocholestrol

39
Q

What type of hormone does cholecalciferol act similarly to?

A

Steroid hormones

40
Q

What are the sources of cholecalciferol? (3)

A

Milk, dairy products

Eggs

Fortified margarine

41
Q

How is ergocalciferol formed?

A

Derived industrially from ergosterol in plants, fungi and moulds

42
Q

What is the function of vitamin D?

A

Maintain correct level of calcium and phosphate in blood to ensure proper bone mineralisation

43
Q

What does a vitamin D deficiency cause?

A

Rickets in children

Osteomalacia in adults

44
Q

What are the symptoms of rickets? (2)

A

Decreased mineral to matrix ratio in bone = bending of long bones and kyphosis

Delayed tooth eruption

45
Q

What are the symptoms of osteomalacia? (3)

A

Muscle weakness

Bone pain

Decalcification of long bones

46
Q

What intake of vitamin D is toxic?

A

10xRNI (100ug)

47
Q

What does vitamin D overdose cause? (3)

A

Hypercalcaemia

GI tract disturbances

Calcification of soft tissues

48
Q

What are the sources of vitamin K? (3)

A

Green leafy vegetables

Bacteria flora of jejunum and ileum

Small amounts in milk, eggs and cereals

49
Q

What does a vitamin K deficiency cause? (2)

A

Defective blood clotting

Haemorrhagic disease of newborns - may have intracranial haemorrhages

BMS15 (4 decks)

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