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M104 T1 > M104 T1 L9 > Flashcards

M104 T1 L9 Flashcards

1
Q

What are all vitamins derived from?

A

plants - they are organic molecules

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2
Q

What is the generalised role of vitamins and organic molecules in the body?

A

to act as co-enzymes in metabolic pathways

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3
Q

What are most minerals and trace elements sourced from?

A

food - bc where food is grown and how it is processed

they are inorganic molecules

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4
Q

Which trace element is scarce in UK grown plants?

A

selenium

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5
Q

How many vitamins are required by humans in total?

A

13 vitamins

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6
Q

What are the two main types of vitamins and how many are there of each?

A 
fat soluble (4 - ADEK)
water soluble (9 - C & 8xBs)
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7
Q

What are the names of the water soluble vitamin Bs?

A 
B1 - thiamine 
B2 - riboflavin 
B3 - niacin 
B5 - pantothenic acid 
vitamin B6
B9- folate
vitamin B12
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8
Q

What are the water soluble vitamin Bs numbered?

A

1235, 6912

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9
Q

In what group is iron-deficiency anaemia common in?

A

adult women and older girls

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10
Q

In what groups is low vitamin D common in?

A

in adults and older children, both male and female

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11
Q

In what groups is a functional riboflavin (B2) deficiency common in?

A

adults and older children

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12
Q

What are the micronutrients that are consumed at a low level at a population level? (Di-fR)

A

vitamin D
iron
functional riboflavin (B2)

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13
Q

What is the effect of low vitamin D?

A

reduced bone health < increased risk of Rickets and Osteomalacia

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14
Q

What are the health implications of a B2 deficiency?

A

the health implications are not known

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15
Q

Why are females more susceptible to iron deficiency anaemia?

A

due to the menstrual cycle and the associated loss of blood, women tend to have lower iron stores

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16
Q

What is the name of vitamin B1?

A

thiamine

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17
Q

What is the name of vitamin B2?

A

riboflavin

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18
Q

What is the name of vitamin B3?

A

niacin

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19
Q

What is the name of vitamin B5?

A

pantothenic acid

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20
Q

What is the name of vitamin B9?

A

folate

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21
Q

What vitamins do alcoholics tend to be deficient in?

A

B1 and vitamin D

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22
Q

What conditions do alcoholics tend to have?

A

alcohol liver disease

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23
Q

What deficiencies are associated with IBD?

A

selenium, iron, zinc
vitamins B1, 6, 9, 12
vitamin D & K

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24
Q

What deficiencies are associated with obesity?

A

vitamin D

copper and zinc

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25
Q

Why does IBS cause deficiencies?

A

bc a large portion of the SI can be damaged - this can include damage to the main site full of micronutrients

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26
Q

What are the absorption sites for vitamin C?

A

Buccal mucosa
Stomach
SI

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27
Q

How is vitamin C absorbed into the body?

A

via the buccal cavity - passive diffusion

via the GI tract - a carrier-mediated transport system

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28
Q

When the mucosal concentration is less than 6mmol/L, if 20mg or less of vitamin C is ingested, what percentage is absorbed?

A

98%

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29
Q

When the mucosal concentration is less than 6mmol/L, if 100mg or more of vitamin C is ingested, what percentage is absorbed?

A

6%

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30
Q

What condition is a vitamin C deficiency usually associated with?

A

scurvy

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31
Q

How many cases of scurvy are there in the UK / year about?

A

1 or 2

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32
Q

What groups of people usually suffer from scurvy?

A

older people or homeless people

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33
Q

What are the symptoms of scurvy

A

bleeding gums and bleeding mucosal tissue

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34
Q

What is the dietary source of vitamin B1?

A

it is common in all food

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35
Q

What is the dietary source of vitamin B2?

A

it is common in most foods in co-enzyme form

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36
Q

What are the dietary sources of vitamin B12?

A

meat, fish, milk, cheese, eggs

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37
Q

What are the absorption sites for vitamin B1?

A

Jejunum and Ileum

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38
Q

What is the absorption site for vitamin B2?

A

the SI

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39
Q

What is the absorption site for vitamin B12?

A

the distal portion of the ileum

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40
Q

How is vitamin B1 absorbed into the body at low concentrations?

A

by the active Na+ dependent processes

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41
Q

How is vitamin B1 absorbed into the body at high concentrations?

A

by passive diffusion

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42
Q

What counts as a high concentration of vitamin B1

A

> 8mg in single dose

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43
Q

What is Wernicke-Korsakoff syndrome caused by?

A

B1 deficiency

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44
Q

How is vitamin B2 absorbed into the body?

A

first it is released by proteolytic proteins

it is then hydrolysed by brush border enzymes

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45
Q

How is vitamin B12 absorbed into the body?

A

it is released from proteins by pepsin and HCL
the B12 binds with R Factor
B12 is released from TC in the jejunum and binds to IF
the B12 –IF complex binds with receptors at distal ileum and B12 is slowly absorbed

46
Q

What is transcorrin otherwise known as?

A

R Factor

TC

47
Q

From what sites is R Factor located?

A

salivary glands

in bile, gastric and pancreatic secretions

48
Q

From where is IF released?

A

from the stomach

49
Q

What is pernicious anaemia caused by?

A

the immune system to attack the cells in your stomach that produces IF
vitamin B12 is needed to make RBCs
IF binds vitamin B12 so that it can be absorbed in the intestines

50
Q

How do patients with pernicious anaemia feel?

A

very week

51
Q

What groups suffer from pernicious anaemia?

A

in older people

in people who can’t absorb vitamin V12 bc of damage to the SI

52
Q

Why do older people tend to get pernicious anaemia?

A

bc with age, people release less HCl and IF
both of these are required for the effective transport and then subsequent absorption of vitamin B12 with swollen the test.

53
Q

What do vitamins act like?

A

co-enzymes

54
Q

How is vitamin B12 absorbed in the duodenum?

A

the B12-IF complex binds with IF receptors in the presence of Ca2+
B12 is then absorbed into the plasma

55
Q

How is vitamin B12 absorbed in the stomach?

A

it combines with R factor in the presence of HCl

56
Q

How is vitamin B12 absorbed in the jejunum?

A

the new B12-R complex is degraded

free B12 combines with IF

57
Q

Why is Vitamin B12 and folate often associated with eachother?

A

bc they share a common metabolic cycle

58
Q

What is the effect of vitamin B12?

A

it can block the effect of folate deficiency

59
Q

What is vitamin A associated with?

A

good night vision (B&W)

60
Q

What is the dietary source of vitamin A?

A

animals

61
Q

What is the structure of vitamin A like?

A

a long chain FA

62
Q

What is the precursor of vitamin A?

A

beta carotenoid found in plants

63
Q

What is the absorption site for vitamin A?

A

the SI

64
Q

How is vitamin A absorbed?

A

the Protein-Retinol complex is hydrolysed by pepsin in the stomach
then by other proteolytic enzymes in SI
then they’re absorbed

65
Q

What is the absorption site for beta carotenoids?

A

the duodenum and jejunum

66
Q

How are beta carotenoids absorbed?

A

they are solubilised into micelles, absorbed through membrane and converted to retinol

67
Q

What is the dietary source of vitamin D?

A

some animal food, e.g. milk

it is synthesised in human skin from UV light

68
Q

What is the absorption site for vitamin D?

A

only about 50% is absorbed
Dietary Vitamin D2
UV light Vitamin D3

69
Q

How is vitamin D absorbed into the intestinal mucosal cell?

A

via passive diffusion from mixed micelles

70
Q

What is the route by which vitamin D is activated?

A

vitaminD2 and D3 (+ 25-hydroxylase) < 25(OH)D < 1, 25(OH)D

71
Q

What does 25(OH)D stand for?

A

25hydroxy-vitaminD

72
Q

What is the active form of vitamin D vitamin?

A

vitamin 1,25-dihydroxyvitamin D

73
Q

What is the main circulating form of vitamin D vitamin?

A

25(OH)D

74
Q

What converts 25(OH)D into 1, 25(OH)D?

A

the kidney and other tissues

75
Q

What are the two forms of vitamin D?

A

D2 - the dietary form

D3 - the ultraviolet form

76
Q

Where are the 25-hydroxylase enzymes located?

A

in the liver

77
Q

What are the risk factors for vitamin D deficiency?

A 
Pigmented skin 
Lack of sunlight exposure
Skin concealing garments or strict sunscreen use
Multiple, short interval pregnancies
Elderly or housebound
Vegan / vegetarian or high phytate consumption
Malabsorption 
Use of anticonvulsants
78
Q

What are examples of anticonvulsants?

A

rifampicin
cholestyramine
anti-retrovirals

79
Q

What conditions can lead to malabsorption?

A

IBD, coeliac disease, pancreatic insufficiency

80
Q

What are the specific effects of vitamin D on the immune system?

A

it increases the differentiation of macrophages
it increases bacterial killing
it lowers cytokine production
it lowers antigen presentation

81
Q

What are the overall effects of vitamin D on immunity?

A

it improves the ability to scavenge infective agents of bacteria and viruses
it improves the ability to ensure that bacteria are scavenged then destroyed

82
Q

What is the effect of vitamin D on T cells?

A

it reduces the production of TH1 cytokines

it increases the production of TH2 cytokines

83
Q

What is the effect of a reduced population of TH1 cytokines in the body?

A

it reduces the risk of autoimmune disorders or allergies

84
Q

What is the effect of a reduced cytokine production in the body?

A

reduces inflammation

85
Q

What are the dietary sources of calcium?

A

dairy and plant products

86
Q

What are the absorption sites for vitamin C?

A 
Buccal mucosa
Stomach
the primarily Duodenum
the jejunum
colon for the fermentation of plant products
87
Q

What percentage of vitamin C is absorbed in an acid medium?

A

20-30%

88
Q

How is vitamin D absorbed into the body in the duodenum?

A

via a vitamin D-dependent Ca2+ transport system

89
Q

Where in the SI is vitamin D intake low and requirement high?

A

the duodenum

90
Q

Where in the SI is vitamin D intake high?

A

the jejunum

91
Q

How is vitamin D absorbed into the body in the jejunum?

A

via a passive process

92
Q

What is the dietary source of iron?

A

animal food - haem iron

plant food - non-haem iron

93
Q

What is the absorption site for iron?

A

mostly from the proximal SI

94
Q

In what form is haem iron absorbed?

A

intact porphyrin complex

95
Q

In what form is non-haem iron absorbed?

A

in ferrous form after being ionized from ferrous to ferric form

96
Q

What percentage of iron is absorbed when stores are low?

A

35%

97
Q

What percentage of iron is absorbed when stores are normal?

A

5%

98
Q

Which iron complex is it easier to absorb iron from?

A

the haem iron complex bc the body has a wider variety of enzymes help to release it from its transport

99
Q

How do iron tablets affect anaemic patients and why?

A

causes black tarry stools

this is bc most of the iron being taken in is not being absorbed

100
Q

How should iron tablets be taken?

A

always on an empty stomach, never with food

mostly with just water

101
Q

What can iron tablets be taken with to improve iron absorption and why?

A

vitamin C bc it changes the iron from its ferrick to its ferrous form

102
Q

What is another name for vitamin C?

A

ascorbic acid

103
Q

What percentage of iron will be absorbed by anaemic patients on tablets?

A

between 6 - 8%

104
Q

calcium signalling

A

second messenger

105
Q

What processes in the developmental stage is calcium signalling involved in?

A

the activation of eggs
the early embryonic development
the right left partitioning of the body
organ development

106
Q

What adult physiological processes is calcium signalling involved in?

A

bone formation
blood clotting cells
cardiac contractions

107
Q

Why do blood clotting cells require calcium signalling?

A

the clotting cascade requires Ca2+ for brain function and neurotransmission

108
Q

What are the roles of iron in the body?

A 
is an oxygen binding site in Hb and myoglobin
helps synthesise many proteins
helps synthesise DNA
helps produce NTs
boosts immunity
109
Q

How does selenium work as an antioxidant?

A

by preventing damage to cells from external environmental particles

110
Q

What are some of the liver manifestations of alcohol overconsumption?

A

fatty liver, alcoholic hepatitis, and chronic hepatitis with liver fibrosis / cirrhosis

M104 T1 (15 decks)

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