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55 Cards in this Set
- Front
- Back
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what type of nutrient is iron?
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micronutrient
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how much of your body iron is stored?
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25%
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where is the majority of your Iron stored?
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macrophages
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how many grams of iron does an average adult contain?
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4g
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how many g of iron are contained in erythrocytes of an average human?
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2.5g
over half |
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how much heme incorporated iron is recycled every day?
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20mg
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how many g of iron are contained in proteins and respiratory enzymes?
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.5g
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is the body able to get rid of some of its iron stores voluntarily?
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No
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how much iron does the body lose on a daily basis? How much is consumed?
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1-2 mg lost
15-20 mg consumed |
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what are the 4 forms of dietary iron and what are their names?
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Fe3+ = ferric
Fe2+ = ferrous Fe 0 = elemental Heme |
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where do you find heme iron in the diet?
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Meat and fish
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what is the most bioavailable form of iron?
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heme
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where would you find non-heme iron in the diet?
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veggies
fruits eggs |
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what is the least bioavailable form of iron?
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Fe0, elemental
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what is the most abundant form of iron?
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Fe3+, but it is not very bioavailable in this state
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how is ferric iron solubilized?
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stomach acid, then it is chelated to glucose, AAs, mucin, etc
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what do antacids do to iron absorption?
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decrease it due to the decrease in stomach pH
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what type of iron are most supplements composed of?
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Ferrous iron
Fe2+ |
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what type of iron absorption is effected by meal consumption?
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non-heme iron
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what dietary items enhance iron absorption?
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Vit C
AAs Acidic foods |
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what dietary items decrease iron absorption?
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phytates (grains,legumes)
polyphenols (tea and coffee) Phosphates (egg yolk) Oxalate (spinich) calcium or zinc |
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where is iron absorbed?
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duodenum and upper jejunum
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what is the difference in absorption between heme and non-heme iron?
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Heme- absorbed intact, then degraded by HO within the enterocyte
non-heme- absorbed via DMT carrier |
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what transports iron through the cytosol of enterocytes?
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mobiliferrin
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how is iron exported from cells?
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via ferroportin
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why is iron always transported in the ferric form?
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because the ferrous form can undergo the fenton reaction
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what is produced by the fenton reaction?
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OH- radicals
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what protein transports iron through the blood?
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transferrin
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what are the 3 stares of transferrin?
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apotransferrin
monoferric transferrin diferric transferrin |
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how is iron taken in by growing cells?
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TfReceptors bind Tf
endocytosis proton pump decreases pH iron brought into cyto via DMT TfR and Tf are returned |
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what are the 2 iron storage molecules?
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ferritin
hemosiderin |
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where are the main macrophage storage sites for iron?
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Liver
Spleen Bone marrow |
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what is the best test to assess body iron stores?
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by testing serum ferritin levels.
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why do you find small amounts of ferritin in the serum?
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due to normal cell lysis and turnover
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is ferritin intracellular or extracellular?
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intracellular
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what helps to sequester large amounts of iron during times of iron overload?
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hemosiderin
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what are the 4 types of cells that contain ferroportin?
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Macrophages
placental trophoblasts hepatocytes duodenal enterocytes |
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what molecule is the "iron hormone" ?
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Hepcidin
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what does hepcidin do?
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controls iron absorption and mobilization
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what would happen to hepcidin levels in the serum after acute blood loss?
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hepcidin levels would decrease to increase ferroportin expression and iron absorption
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what would hepcidin levels be like if there were large amounts of hemosiderin in cells?
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Hepcidin levels would be high in order to reduce ferroportin expression and reduce iron absorption
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what disease would result from a deficiency of hepcidin?
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hemochromotosis
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where is hepcidin made?
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the liver
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what happens to hepcidin levels during an infection?
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they are increased
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what happens to hepcidin levels during hypoxia or increased erythroid demand?
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they are decreased
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if iron levels are high, what can we say about TfR mRNA expression and Ferritin mRNA expression?
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TfR mRNA is degraded by RNase activity
Ferritin mRNA is transcribed into protein |
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what happens to IRP during low iron conditions?
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binds TfR mRNA and protects it from degradation
binds to Ferritin mRNA and prevents its expression |
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what happens to IRP during high iron conditions?
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IRP is bound to iron
good for ferritin, bad for TfR |
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what cell produces lactoferrin?
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neutrophils
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where is lactoferrin bound iron stored?
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macrophages
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a patient has a MRSA boil. what are all of the events that lead to hypoferremia in the tissue?
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Macs release IL-1 and IL-6
IL-1 induces neutrophils to release lactoferrin, which binds any free iron and is subsequently taken in by the macrophages IL-6 induces hepatocytes to release hepcidin, which reduces ferroportin levels on Macs (and elsewhere) and reduces iron excretion |
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how would chronic infections lead to anemia?
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if IL-1 and IL-6 levels are too high, for too long, iron wont be delivered to the bone marrow and RBCs wont be made
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how much iron is in 1ml of blood?
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.5 mg
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if an adult female donates 500 ml of blood and is not pregnant, how much iron did she lose that month?
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300 mg to 320mg
daily loss + menstruation + donation |
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how many mg iron/day are transferred to the fetus during the last trimester?
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3-4 mg/day
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