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