LMP301 Lecture 13: Iron & Hemoglobin Flashcards Preview

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Flashcards in LMP301 Lecture 13: Iron & Hemoglobin Deck (62)
1

Majority of iron comes from...

diet

2

dietary iron is in the form...

ferric
Fe3+

3

Ferric iron is insoluble...

in basic conditions

4

5 - 10% of iron is absorbed at...

the duodenum

5

What happens to iron in the stomach?

- converted to Fe2+
- Fe2+ can be soluble in the basic duodenum, and thus absorbed

6

what increases iron absorption?

- ascorbic acid
- sugars
- AA

7

What decreases iron absorption?

- eggs
- cheese
- milk
- veggies
- tea

8

desquamation

the shedding of epithelial cells

9

Iron is lost through...

- desquamation
- menstrual flow
- urine

10

Iron is stored in...

- RBC (70%)
- Ferritin (20%)
- Myoglobin (5%)

11

Ferritin

intracellular protein that stores iron

12

__ is the transport protein for iron in the plasma

transferrin

13

Process of iron uptake into cells

1. transferrin receptor binds transferrin holding iron
2. endosome engulfs
3. endosome pH changes to acidic
4. iron is released from transferrin, and is pumped out of endosome
5. (apo)transferrin-receptor is recycled

14

(apo)transferrin

transferrin without iron bound to it

15

transferrin has ____ binding sites for ___

2
Fe+++

16

Occupancy of transferrin sites

not always occupied
- only 25-50% of transferrin is normally saturated

17

What used to be an indirect way to measure transferrin concentration?

total iron binding capacity (TIBC)

18

Iron is an ____ element

essential

19

free iron is...

toxic

20

Iron is found complexed with...

- hemoglobin
- myoglobin
- cytochromes

21

binding of iron to proteins occurs though...

heme

22

Heme

- inorganic molecule
- Fe goes in the middle of the ring

23

Iron is stored as...

- ferritin
- hemosiderin

24

Ferritin can bind up to...

4500 iron atoms
This protects cells from free iron damage

25

Hemosiderin

= insoluble ferritin
- release iron slowly

26

1/3 of iron stores are in...

- liver
- spleen
- bone marrow

27

Iron diseases

- iron deficiency (anemia)
- iron overload
- iron poisoning
- chronic disease

28

Iron deficiency is common in...

women, children, elderly

29

Iron deficiency is usually associated with ___ because...

anemia
Iron stores are used up, so can't make enough RBC

30

causes of iron deficiency

- loss of blood
- inadequate intake

31

What will happen to total iron binding capacity (TIBC) when iron decreases?

Increases
- there are more free sites, so the capacity increases

32

What is a good indicator of iron deficiency?

decreased serum ferritin

33

biochemical test: iron deficiency

- low serum iron
- high TIBC
- low iron saturation (< 25%)
- high serum transferrin
- low serum ferritin
- less Hb
- Hb smaller
- Hb lighter in colour

34

Iron saturation

ratio of ferritin:transferrin

35

hypochromic Hb

less iron in Hb, so colour is light pink instead of red

36

microcytic anemia

RBC becomes smaller than normal

37

symptoms of iron deficiency

- weakness / fatigue
- short breath
- incr. CO
- pale hair & nails
- disturbed behaviour in children
- impaired neurological development in infants

38

Treatment of iron deficiency

- mild: oral supplements (take wit vit C to increase absorption)
- anemia / chronic: erythropoietin
- severe anemia: blood transfusion

39

biochemical results of iron overload

- high serum iron
- high serum ferritin
- low TIBC
- high iron saturation (>50%)

40

Some causes of iron overload

- increased intake
- blood transfusions
- hereditary hemochromatosis

41

AR

hereditary hemochromatosis

42

10% of ____ carry the gene for hereditary hemochromatosis

northern Europeans

43

Occurance of the disease (homo/hetero)

not all homozygous people have the disease, meaning there are factors other than genetics

44

is hereditary hemochromatosis more common in men or women?

men

45

why are women protected from iron overload?

periods

46

symptoms of hereditary hemochromatosis is apparent by...because...

40 years old because the iron toxicity would have had enough time to do damage to some organs

47

gene responsible for hereditary hemochromatosis

HFE
Mutations lead to increased absorption & storage of iron

48

symptoms of hereditary hemochromatosis

- fatigue
- joint pain
- mood swings / depression
- bronze skin colour (liver can't remove pigment)
- type II diabetes (pancreas harmed by iron)
- liver-heart-thyroid dysfunction

49

Iron overload will affect...

- liver
- pancreas

50

diagnosis of hereditary hemochromatosis

- high iron
- genetic testing for HFE gene

51

Treatment for iron overload

- venesection
- screen at risk relatives

52

Iron poisoning is...

acute disorder; extreme iron overload in the body

53

Iron poisoning is common in...

children

54

symptoms of iron poisoning

- nausea
- vomiting
- abdominal pain
- hematemesis (vomit blood)

55

treatment of iron poisoning

chelation with desferrioxamine

56

Why is venesection not used in iron poisoning treatment?

don't want to remove that much blood from children

57

synthesis of Hb is stimulated by...

low oxygen

58

3 common pathological conditions associated with Hb

1. a-Thalassemia
2. B-thalassemia
3. sickle cell anemia

59

a-Thalassemia

- microcytic anemia
- low a-chain synthesis for Hb

60

B-thalassemia

- microcytic anemia
- low B-chain synthesis for Hb

61

Sickle cell anemia

- hemolytic nemia
- affects growth development
- E -> V mutation (on beta chain)

62

Consequences of HbS

- susceptible to hemolysis
- precipitate
- occlude blood vessel -> infarction