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Haematology > Iron > Flashcards

Iron Flashcards

1
Q

What are the functions of iron in the body?

A

Oxygen transport and storage

Role in enzyme function

  • energy metabolism
  • collagen formation
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2
Q

What are the different forms of available iron?

A

Haemoglobin

Myoglobin

Tissue iron

Transported iron - serum iron

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3
Q

What is myoglobin?

A

Oxygen-storing protein in muscle

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4
Q

What is tissue iron?

A

Iron in enzymes

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5
Q

What are the different forms of stored iron?

A

Ferritin

Haemosiderin

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6
Q

What is haemosiderin?

A

Iron in macrophages

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7
Q

How does ferritin react to water?

A

Soluble in water

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8
Q

How does haemosiderin react to water?

A

Insoluble in water

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9
Q

How does the requirement of iron change during pregnancy?

A

Iron requirement increases

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10
Q

Where does most iron in the body come from?

A

Recycling iron already within the body

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11
Q

How is iron stored in the liver?

A

Most of it as ferritin in hepatocytes

Small amount as haemosiderin in kupffer cells

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12
Q

Is iron excreted from the body?

A

No

no mechanism to excrete iron

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13
Q

How is iron lost from the body?

A

Small amount in

  • skin
  • gut cells
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14
Q

How much iron enters and leaves the body per day?

A

1-2mg

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15
Q

What are the different forms of iron in the diet?

A

Haem iron

Non-haem iron

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16
Q

What is haem iron?

A

Haem containing iron

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17
Q

What is the state of iron in haem iron?

A

Ferrous state - Fe2+

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18
Q

What foods contain haem iron?

A

Red meat

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19
Q

What is non-haem iron?

A

Iron on its own

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20
Q

What is the state of iron in non-haem iron?

A

Mainly ferric form - Fe3+

21
Q

What foods contain non-haem iron?

A

Nuts

Grains

Eggs

22
Q

How much iron is required in the diet?

A

10-15mg per day

23
Q

What happens to non-haem iron in the stomach? What type of reaction is this?

A

Fe3+ —–> Fe2+

reduction

24
Q

What facilitates the reduction of Fe3+ in the stomach?

A

Acid of stomach

H+

25
Q

Where does iron absorption occur in the GI tract?

A

Duodenum

Upper jejunum

26
Q

How does iron enter epithelial cells in the small intestine?

A

DMT1 transporter moves Fe2+ from intestinal lumen

into epithelial cell

27
Q

Where is the DMT1 transporter located in the epithelial cell?

A

Apical domain

28
Q

What happens to non-haem iron inside the epithelial cells?

A

Some is stored as ferritin

Rest is exported into the blood

29
Q

How is iron moved from the epithelial cell to the blood?

A

Ferroportin transporter

30
Q

Where is the ferroportin transporter located in the epithelial cell?

A

Basolateral domain

31
Q

What do fetal enterocytes have additional receptors for?

A

Lactoferrin

32
Q

What is the primary source of iron in babies-young children?

A

Lactoferrin

33
Q

How does iron travel in the blood?

A

Bound to transferrin protein

34
Q

How is iron taken up into body cells?

A

Iron-transferrin complex binds to transferrin receptor on cell
iron taken up into cell

35
Q

Which body cell has the highest number of transferrin receptors? How does this affect their iron uptake?

A

Erythroid cells

take up most iron

36
Q

What increases the absorption of non-haem iron?

A

Vit C

37
Q

How does vit C increase absorpton of non-haem iron?

A

Increases acidity of stomach
more Fe3+ reduced to Fe2+
more Fe2+ absorbed

38
Q

What decreases absorption of non-haem iron?

A

Antacids

Tea, coffee

39
Q

What does the regulation of iron absorption depend on?

A

Dietary intake of iron

Body iron stores

Use of iron - erythropoiesis

40
Q

What senses dietary levels of iron?

A

Villi in small intestine

41
Q

What are the mechanisms regulating iron absorption?

A

Expression of transporters

Activity of transporters

42
Q

What are some examples of molecules involved in regulating iron absorption?

A

Hepcidin

HFE protein

43
Q

Where is hepcidin produced?

A

Liver

44
Q

What increases the production of hepcidin?

A

Iron overload

45
Q

What decreases the production of hepcidin?

A

High erythropoietic activity

46
Q

What does hepcidin do? What are the effects?

A

Binds to ferroportin transporter
breaks it down

Prevents iron leaving epithelial cell into blood in small intestine
Prevents macrophages releasing iron

47
Q

How is hepcidin removed from the body?

A

Excreted by kidneys

48
Q

What regulates hepcidin?

A

HFE protein

Transferrin receptor

Inflammatory cytokines

Haematology (12 decks)

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