M104 T1 L9 Flashcards
(110 cards)
1
Q
What are all vitamins derived from?
A
plants - they are organic molecules
2
Q
What is the generalised role of vitamins and organic molecules in the body?
A
to act as co-enzymes in metabolic pathways
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
4
Q
Which trace element is scarce in UK grown plants?
A
selenium
5
Q
How many vitamins are required by humans in total?
A
13 vitamins
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)
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
8
Q
What are the water soluble vitamin Bs numbered?
A
1235, 6912
9
Q
In what group is iron-deficiency anaemia common in?
A
adult women and older girls
10
Q
In what groups is low vitamin D common in?
A
in adults and older children, both male and female
11
Q
In what groups is a functional riboflavin (B2) deficiency common in?
A
adults and older children
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)
13
Q
What is the effect of low vitamin D?
A
reduced bone health < increased risk of Rickets and Osteomalacia
14
Q
What are the health implications of a B2 deficiency?
A
the health implications are not known
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
16
Q
What is the name of vitamin B1?
A
thiamine
17
Q
What is the name of vitamin B2?
A
riboflavin
18
Q
What is the name of vitamin B3?
A
niacin
19
Q
What is the name of vitamin B5?
A
pantothenic acid
20
Q
What is the name of vitamin B9?
A
folate
21
Q
What vitamins do alcoholics tend to be deficient in?
A
B1 and vitamin D
22
Q
What conditions do alcoholics tend to have?
A
alcohol liver disease
23
Q
What deficiencies are associated with IBD?
A
selenium, iron, zinc
vitamins B1, 6, 9, 12
vitamin D & K
24
Q
What deficiencies are associated with obesity?
A
vitamin D
copper and zinc
25
Why does IBS cause deficiencies?
bc a large portion of the SI can be damaged - this can include damage to the main site full of micronutrients
26
What are the absorption sites for vitamin C?
Buccal mucosa
Stomach
SI
27
How is vitamin C absorbed into the body?
via the buccal cavity - passive diffusion
| via the GI tract - a carrier-mediated transport system
28
When the mucosal concentration is less than 6mmol/L, if 20mg or less of vitamin C is ingested, what percentage is absorbed?
98%
29
When the mucosal concentration is less than 6mmol/L, if 100mg or more of vitamin C is ingested, what percentage is absorbed?
6%
30
What condition is a vitamin C deficiency usually associated with?
scurvy
31
How many cases of scurvy are there in the UK / year about?
1 or 2
32
What groups of people usually suffer from scurvy?
older people or homeless people
33
What are the symptoms of scurvy
bleeding gums and bleeding mucosal tissue
34
What is the dietary source of vitamin B1?
it is common in all food
35
What is the dietary source of vitamin B2?
it is common in most foods in co-enzyme form
36
What are the dietary sources of vitamin B12?
meat, fish, milk, cheese, eggs
37
What are the absorption sites for vitamin B1?
Jejunum and Ileum
38
What is the absorption site for vitamin B2?
the SI
39
What is the absorption site for vitamin B12?
the distal portion of the ileum
40
How is vitamin B1 absorbed into the body at low concentrations?
by the active Na+ dependent processes
41
How is vitamin B1 absorbed into the body at high concentrations?
by passive diffusion
42
What counts as a high concentration of vitamin B1
>8mg in single dose
43
What is Wernicke-Korsakoff syndrome caused by?
B1 deficiency
44
How is vitamin B2 absorbed into the body?
first it is released by proteolytic proteins
| it is then hydrolysed by brush border enzymes
45
How is vitamin B12 absorbed into the body?
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
What is transcorrin otherwise known as?
R Factor
| TC
47
From what sites is R Factor located?
salivary glands
| in bile, gastric and pancreatic secretions
48
From where is IF released?
from the stomach
49
What is pernicious anaemia caused by?
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
How do patients with pernicious anaemia feel?
very week
51
What groups suffer from pernicious anaemia?
in older people
| in people who can't absorb vitamin V12 bc of damage to the SI
52
Why do older people tend to get pernicious anaemia?
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
What do vitamins act like?
co-enzymes
54
How is vitamin B12 absorbed in the duodenum?
the B12-IF complex binds with IF receptors in the presence of Ca2+
B12 is then absorbed into the plasma
55
How is vitamin B12 absorbed in the stomach?
it combines with R factor in the presence of HCl
56
How is vitamin B12 absorbed in the jejunum?
the new B12-R complex is degraded
| free B12 combines with IF
57
Why is Vitamin B12 and folate often associated with eachother?
bc they share a common metabolic cycle
58
What is the effect of vitamin B12?
it can block the effect of folate deficiency
59
What is vitamin A associated with?
good night vision (B&W)
60
What is the dietary source of vitamin A?
animals
61
What is the structure of vitamin A like?
a long chain FA
62
What is the precursor of vitamin A?
beta carotenoid found in plants
63
What is the absorption site for vitamin A?
the SI
64
How is vitamin A absorbed?
the Protein-Retinol complex is hydrolysed by pepsin in the stomach
then by other proteolytic enzymes in SI
then they're absorbed
65
What is the absorption site for beta carotenoids?
the duodenum and jejunum
66
How are beta carotenoids absorbed?
they are solubilised into micelles, absorbed through membrane and converted to retinol
67
What is the dietary source of vitamin D?
some animal food, e.g. milk
| it is synthesised in human skin from UV light
68
What is the absorption site for vitamin D?
only about 50% is absorbed
Dietary Vitamin D2
UV light Vitamin D3
69
How is vitamin D absorbed into the intestinal mucosal cell?
via passive diffusion from mixed micelles
70
What is the route by which vitamin D is activated?
vitamin D2 and D3 (+ 25-hydroxylase) < 25(OH)D < 1, 25(OH)D
71
What does 25(OH)D stand for?
25 hydroxy-vitamin D
72
What is the active form of vitamin D vitamin?
vitamin 1,25-dihydroxyvitamin D
73
What is the main circulating form of vitamin D vitamin?
25(OH)D
74
What converts 25(OH)D into 1, 25(OH)D?
the kidney and other tissues
75
What are the two forms of vitamin D?
D2 - the dietary form
| D3 - the ultraviolet form
76
Where are the 25-hydroxylase enzymes located?
in the liver
77
What are the risk factors for vitamin D deficiency?
```
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
What are examples of anticonvulsants?
rifampicin
cholestyramine
anti-retrovirals
79
What conditions can lead to malabsorption?
IBD, coeliac disease, pancreatic insufficiency
80
What are the specific effects of vitamin D on the immune system?
it increases the differentiation of macrophages
it increases bacterial killing
it lowers cytokine production
it lowers antigen presentation
81
What are the overall effects of vitamin D on immunity?
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
What is the effect of vitamin D on T cells?
it reduces the production of TH1 cytokines
| it increases the production of TH2 cytokines
83
What is the effect of a reduced population of TH1 cytokines in the body?
it reduces the risk of autoimmune disorders or allergies
84
What is the effect of a reduced cytokine production in the body?
reduces inflammation
85
What are the dietary sources of calcium?
dairy and plant products
86
What are the absorption sites for vitamin C?
```
Buccal mucosa
Stomach
the primarily Duodenum
the jejunum
colon for the fermentation of plant products
```
87
What percentage of vitamin C is absorbed in an acid medium?
20-30%
88
How is vitamin D absorbed into the body in the duodenum?
via a vitamin D-dependent Ca2+ transport system
89
Where in the SI is vitamin D intake low and requirement high?
the duodenum
90
Where in the SI is vitamin D intake high?
the jejunum
91
How is vitamin D absorbed into the body in the jejunum?
via a passive process
92
What is the dietary source of iron?
animal food - haem iron
| plant food - non-haem iron
93
What is the absorption site for iron?
mostly from the proximal SI
94
In what form is haem iron absorbed?
intact porphyrin complex
95
In what form is non-haem iron absorbed?
in ferrous form after being ionized from ferrous to ferric form
96
What percentage of iron is absorbed when stores are low?
35%
97
What percentage of iron is absorbed when stores are normal?
5%
98
Which iron complex is it easier to absorb iron from?
the haem iron complex bc the body has a wider variety of enzymes help to release it from its transport
99
How do iron tablets affect anaemic patients and why?
causes black tarry stools
| this is bc most of the iron being taken in is not being absorbed
100
How should iron tablets be taken?
always on an empty stomach, never with food
| mostly with just water
101
What can iron tablets be taken with to improve iron absorption and why?
vitamin C bc it changes the iron from its ferrick to its ferrous form
102
What is another name for vitamin C?
ascorbic acid
103
What percentage of iron will be absorbed by anaemic patients on tablets?
between 6 - 8%
104
calcium signalling
second messenger
105
What processes in the developmental stage is calcium signalling involved in?
the activation of eggs
the early embryonic development
the right left partitioning of the body
organ development
106
What adult physiological processes is calcium signalling involved in?
bone formation
blood clotting cells
cardiac contractions
107
Why do blood clotting cells require calcium signalling?
the clotting cascade requires Ca2+ for brain function and neurotransmission
108
What are the roles of iron in the body?
```
is an oxygen binding site in Hb and myoglobin
helps synthesise many proteins
helps synthesise DNA
helps produce NTs
boosts immunity
```
109
How does selenium work as an antioxidant?
by preventing damage to cells from external environmental particles
110
What are some of the liver manifestations of alcohol overconsumption?
fatty liver, alcoholic hepatitis, and chronic hepatitis with liver fibrosis / cirrhosis
