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Block 2 week 7 > Iron Metabolism > Flashcards

Iron Metabolism Flashcards

1
Q

Oxygen can react with (blank) in one electron red-ox reactions.

A

iron

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2
Q

Oxygen transport and storage are done via what two things?

A

myoglobin and hemoglobin

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3
Q

Where do you find iron-containing proteins?

A

amino acid metabolism
inflammatory responses
Electron transport -cytochromes

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4
Q

Iron and O2 generate (blank). There are many mechanisms in place to avoid excessive production of these.

A

free radicals

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5
Q

(blank) is sequestered by binding proteins, protoporphyrins, and Fe-S centers

A

Iron

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6
Q

Where do infants get iron from?

A

lactoferrin in mothers milk

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7
Q

Where do you get absorption of iron?

A

upper small intestine (mostly duodenum)

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8
Q

Heme-iron is taken up by a heme transporter (HT) protein. Once in cell, heme (blank) splits iron from heme

A

dioxygenase

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9
Q

(blank) promotes Fe+2 to Fe+3

Fe+3 is reduced to Fe+2 by a ferric reductase: duodenal cytochrome b (Dcytb).

A

Gut environment

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10
Q

What is the absorption of Iron in the gut?

A

Fe+2 then transported by DMT1 across apical membrane of enterocyte as Fe+2.
Ferroportin (FP) aided by hephaestin (Hp)(redox protein) makes the Fe2+ into Fe 3+ and transports it into the interstitial fluid then to plasma
Plasma Fe+3 binds to apo-transferrin to form transferrin
Some Fe+2 is stored as Fe+3-ferritin in cell

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11
Q

What is the major storage protein of iron?

A

ferritin (4500 irons Fe3+ to one protein molecule)

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12
Q

When do you see the aggregated form of ferritin?

A

in iron overload where it is hemosiderin (partially degraded)

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13
Q

(blank) level is the most convenient laboratory test to estimate iron stores
Under steady state conditions, the serum ferritin level correlates with total body iron stores

A

serum ferritin

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14
Q

Iron (III) is (blank) at physio pH, this is why transferrin is need to by Iron III to avoid precipitation in plasma

A

insoluble

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15
Q

Is it healthy to have low conc. of free iron?

A

no it is damaging

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16
Q

Essentially all plasma iron is bound to (blank). How many irons does this carry?

A

transferrin

2 Fe 3+

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17
Q

What is the normal saturation % of transferrin with iron?

A

33%

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18
Q

Describe iron uptake into the cell

A

transferrin bind iron-> transferrin iron complex binds to transferrin receptors (Tfr). the Tfr-diferric(2 irons)-Transferrin complex then gets sucked into an endosome and brough into the cell-> endosome becomes acidic and iron is released from complex-> iron is taken by mitochondria and put into heme by ferrochetolase-> apotransferrin is recycled back to plasma to get more iron.

19
Q

What is the primary storage site of iron?

A

liver

20
Q

What is the master control organ of iron homeostasis and produces the peptide hormone hepcidin?

A

liver

21
Q

What does hepicidin do?

What is the production of this stimulated by?

A

Inhibitor of processes that put iron into the blood
Directly interacts with ferroportin

Production is stimulated in:
Inflammation
Iron overload

22
Q

(blank) controls the main inflows of iron into plasma.

hepcidin binds directly to (blank) which is the hepcidin receptor.

A

hepcidin

ferroporFtin

23
Q

What happens when hepcidin is high?

A

hepcidin is internalized away from membrane, iron is trapped in enterocytes, macrophages, and hepatocytes, level of circulating iron goes down
(iron uptake is high)

24
Q

What happens when hepcidin is low?

A

iron enters plasma at high rates (iron uptake is low)

25
Q

What is the major site of iron absorption in the small intestine?

A

the duodenum

26
Q 
What happens in each of these cells:
villus cell or duodenal epithelial cell?
liver parenchymal cell?
reticuloendothelial macrophages?
red blood cell precursor?
A

dietary iron absoprtion
iron storage
iron recycle
heme synthesis

27
Q

Lots of ferritin is not needed in the face of low iron stores because ferritin is an (blank) storage protein.

A

intracellular

28
Q

Extracellular iron concentration is sensed through the interaction of (blank) with (blank). If you have a lot of iron what will be made?

A

holotrasnferrin and TFRI/TFR2 (transferrin receptors)

ferritin and hepcidin

29
Q

(blank) is the Inappropriate increase in intestinal iron absorption resulting in deposition of excessive amounts of iron in parenchymal cells with eventual tissue damage and impaired function of organs.

A

hemochromatosis

30
Q

You get (blank) when you have saturation of iron-binding proteins

A

hemochromatosis

31
Q 
What does this describe?
Deposition of hemosiderin in the tissues (aggregated ferritin)
Primary affected tissues
Liver - cirrhosis
Pancreas - diabetes
Skin – bronze; bronze diabete
A

hemochromatosis

32
Q

What are these primary causes of:
Autosomal recessive allele
Locus designated HFE
Major histocompatibility complex (MHC) class-1 gene.
Protein associates with b2-microglobulin.

A

hemochromatosis

33
Q

What is the mechanism of hemochromatosis/

A

messed up HFE/transferrin interaction resulting in increased uptake of iron

34
Q

What is the primary cause of hemochromatosis?

A

genetics

35
Q

Iron overload is reflected in serum (blank) concentrations

A

ferritin

36
Q

serum ferritin contains (blank) iron but tissue ferritin contain (blank) iron. HOw is it measured?

A

little to none
A LOT of
ug/L

37
Q

What happens to your serum ferritin levels as you age?

A

it increases

38
Q

What is the most common cause of poisoning of young children? What is the treatment?

A

iron poisoning (too many flinstones vitamins
strong laxative,
IV deferoxamine mesylate (Desferal)
-Binds iron and excreted in urine

39
Q

What is this:
Serum free iron not bound to transferrin
Lipid peroxidation occurs, resulting in damage to blood vessels and Mitochondria

A

iron toxicity

40
Q

The most common cause of anemia is (blank)

A

iron deficiency

41
Q

In most adults, iron deficiency results from (blank)

A

blood loss (~5% of premenopausal women in US)

42
Q

Most functional defects in iron deficiency occur with the development of what three things?
+

A

anemia
Weakness and pallor
Exercise intolerance

43
Q

Women who donate blood will develop (blank) more often than men

A

iron deficiency

Block 2 week 7 (9 decks)

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