Lectures 10 and 11 - Iron Flashcards

1
Q

what is the most important factor effecting bioavailability or iron

A

iron status

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2
Q

how does pregnancy affect iron absorption

A

increases

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3
Q

how does recent iron intake affect iron absorption

A

the mucosal iron block = large amount of iron will decrease absorption of iron you consume after this

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4
Q

what is the relative absorption of haem iron

A

~25-30%

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5
Q

what is the relative absorption of non heam iron

A

~5-15%

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6
Q

what are the enhancers of iron absorption

A

vitamin C and flesh meats (meat, fish, poultry factor)

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7
Q

what are inhibitors of iron absorption

A

phytate, tannins and oxalic acid

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8
Q

how is heme iron absorbed and what happens when it is in the enterocyte

A

heme iron is transported through heme transporter into enterocyte

heme oxygenase reacts with the heme and removes the iron ion from the heme molecule

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9
Q

how is non heme iron absorbed and what happens prior to this

A

non heme iron in the diet is in the Fe3+ form (ferric form)

duodenal cytochrome B reduces the non heme iron from the ferric form (Fe3+) to the ferris form (Fe2+)

the ferris form is the absorbed through the transport of DMT1

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10
Q

some iron will be stored as ……… and this will be lost by ….

A

some iron will be stored as ferratin in the mucosa, which will be lost by shedding of epithelial cells

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11
Q

what will transport iron out of the enterocyte

A

ferroportin

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12
Q

ferris form of iron is really reactive so you do not want this floating around in the body, what converts it to Fe3+ before it goes to the rest of the body

A

hephaestin

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13
Q

during high iron intake, what will diferric transferrin bind to in the liver and what will this cause the release of

A

TfR1 = will then release HFE

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14
Q

HFE released from TfR1 will bind to what and what will the stimulate

A

HFE binds to TfR2 stimulating hepcidin synthesis

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15
Q

what does hepcidin bind to and what does this cause

A

ferroportin on enterocytes and macrophages

  • causes hepcidin-ferroportin complex to internalise and be degraded

meaning Fe trapped inside the enterocyte and cant be absorbed into the body

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16
Q

~67% body Fe is in the form of

A

haemoglobin

17
Q

~4% of body Fe is in the form of

A

myoglobin

18
Q

~0.2% of body Fe is for enzymes involved in ….

A
  • energy metabolism
  • neurotransmitter formation
  • bacterial killing leukocytes
19
Q

what are the two forms of storage Fe (which is the efficient way and what is not as effective)

A
  • ferritin = most effective way of storage
  • haemosiderin
20
Q

how is iron excretion controlled in the body

A

there is no controlled excretion of iron from the body

21
Q

what are the ways the body loses iron

A

epithelial cells

fluids

22
Q

formation of erythrocytes requires how much iron

A

~30mg Fe/day

23
Q

how does majority of iron reutilisation occur

A

majority from breakdown old red blood cells by macrophages in spleen and liver

24
Q

what is the difference of iron deficiency anaemia and depletion of iron stores

A

iron deficiency anaemia affects the haemoglobin levels

25
Q

symptoms of iron deficiency anaemia

A
  • decreased growth
  • behavioural disturbance
  • decreased cognitive function
  • fatigue

etc

26
Q
  • how are pre term infants at risk of iron deficiency
A

haven’t had enough time to accrue their iron stores

27
Q

how are infants are risk of iron deficiency

A

high growth rate and pretty small appetite

28
Q

what adults are at risk of iron deficiency

A
  • menstruating women
  • pregnant women
  • blood donors
29
Q

types of iron supplements to help iron deficiency

A

ferrous sulphate tablet or liquid

30
Q

diet is affective in help non anaemia iron deficiency but not as effective as

A

supplements

31
Q

what is acute iron toxicity

A

unintentional overdose iron tablets

32
Q

what is hereditary haemochromatosis and what does this lead to

A

genetic condition = mutation to the HFE gene

poor control of iron absorption = iron accumulates in liver, pancreas, heart muscle …..

33
Q

“african” iron overload was thought it was to do with intake of beer from cast iron drums but what was it really from

A

unidentified gene responsible

34
Q

what is the RDI or adult men and women

A

RDI men : 8mg/day

RDI women : 18mg/day