Cellular Iron Incorporation and Storage Quiz
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Questions and Answers

What is the role of hepcidin in the regulation of iron absorption?

  • Stimulates iron transport in the blood
  • Promotes iron absorption from the intestines into the blood
  • Inhibits iron absorption from the intestines into the blood (correct)
  • Facilitates iron storage in the liver

    • Which section of Lippincott Illustrated Reviews in Biochemistry covers the topic of heme degradation?

  • Chapter 21, section on Heme degradation (correct)
  • Chapter 16, section on Hemoglobin synthesis
  • Chapter 28, sections on folate and vitamin B12
  • Chapter 29, section III.B on Iron

    • What are the main carriers involved in intestinal iron absorption?

  • Haptoglobin and hepcidin
  • Ferritin and transferrin
  • DMT1 and ferroportin (correct)
  • Hemoglobin and myoglobin

    • What is the function of iron in the human body?

    <p>Synthesis of red blood cells</p> Signup and view all the answers

    What is the epidemiology of hemochromatosis?

    <p>More common in individuals of Northern European descent</p> Signup and view all the answers

    Which section of Lippincott Illustrated Reviews in Biochemistry addresses the functions of iron, the way it is bound to proteins, and its distribution in tissues?

    <p>Chapter 29, section III.B on Iron</p> Signup and view all the answers

    Which form of iron is absorbed more efficiently?

    <p>Ferric iron</p> Signup and view all the answers

    What is the major regulatory hormone for iron absorption and use?

    <p>Hepcidin</p> Signup and view all the answers

    Which enzyme cooperates with membrane transporters to change the oxidation state of iron?

    <p>Ferroxidases</p> Signup and view all the answers

    Where is excess dietary iron stored in the body?

    <p>Reticuloendothelial macrophages</p> Signup and view all the answers

    What facilitates the uptake of iron from the intestine?

    <p>Ascorbate</p> Signup and view all the answers

    Which protein is the main carrier of iron in circulation?

    <p>Transferrin</p> Signup and view all the answers

    What is measured as the total iron binding capacity by transferrin?

    <p>Total iron atoms carried by transferrin</p> Signup and view all the answers

    How do cells acquire iron through receptor-mediated endocytosis?

    <p>By releasing free iron into the cytoplasm</p> Signup and view all the answers

    What is the role of heme and iron-containing proteins in individual cells?

    <p>They deliver iron to the cells</p> Signup and view all the answers

    What is the main form of stored iron in cells?

    <p>Ferric iron</p> Signup and view all the answers

    Where is dietary iron generally liberated as?

    <p>Fe3+ form</p> Signup and view all the answers

    Which component facilitates the uptake of non-heme iron in the duodenum?

    <p>Ascorbate</p> Signup and view all the answers

    Which type of anemia is characterized by bone marrow failure?

    <p>Aplastic anemia</p> Signup and view all the answers

    What is the daily iron allowance for menstruating women in the US?

    <p>18 mg</p> Signup and view all the answers

    Which condition causes an inability to use iron for heme synthesis?

    <p>Sideroblastic anemia</p> Signup and view all the answers

    What is the effect of the C282Y mutation in the HFE gene on hepcidin secretion?

    <p>Reduces hepcidin secretion</p> Signup and view all the answers

    What is the treatment for hemochromatosis?

    <p>Repeated phlebotomy</p> Signup and view all the answers

    What does serum ferritin measure in the body?

    <p>Tissue iron stores</p> Signup and view all the answers

    Which laboratory measurement is a good indicator of iron deficiency or overload?

    <p><strong>Transferrin saturation</strong></p> Signup and view all the answers

    Total Iron Binding Capacity (TIBC) essentially measures what in the blood?

    <p><strong>The total transferrin in the blood</strong></p> Signup and view all the answers

    Serum ferritin is used to confirm which two conditions related to iron?

    <p><strong>Iron storage deficiency and iron storage overload</strong></p> Signup and view all the answers

    What happens to senescent erythrocytes in the body?

    <p>They are taken up by macrophages.</p> Signup and view all the answers

    What is the final product of urobilinogen metabolism?

    <p>Urobilin, excreted in feces.</p> Signup and view all the answers

    How does the body excrete bilirubin from the liver?

    <p>Through bile and intestine.</p> Signup and view all the answers

    In which organelle can iron be translocated for incorporation into heme and iron-sulfur clusters?

    <p>Mitochondria</p> Signup and view all the answers

    What is the major storage form of iron in cells?

    <p>Ferritin</p> Signup and view all the answers

    What is the normal range for blood ferritin in men?

    <p>24 to 336 micrograms per liter</p> Signup and view all the answers

    What is the function of heavy chains in the ferritin complex?

    <p>Gather iron quickly and retain it through enzymatic ferroxidase activity</p> Signup and view all the answers

    What happens in iron deficiency at the cellular level?

    <p>Cells make more transferrin receptor and less apoferritin</p> Signup and view all the answers

    What is the net effect of hepcidin on circulating iron and dietary absorption?

    <p>Lower circulating iron and dietary absorption</p> Signup and view all the answers

    What is the role of hepcidin in the body during infections and cancers?

    <p>Restricts iron supply by increasing hepcidin levels</p> Signup and view all the answers

    Where does the blockage of ferroportin occur due to hepcidin action?

    <p>Intestine, liver, and macrophages</p> Signup and view all the answers

    What happens to iron from worn-out RBCs?

    <p>It is recycled from macrophages to the bone marrow</p> Signup and view all the answers

    What is the daily balance of iron absorption and loss in adults?

    <p>Iron absorption exceeds iron loss</p> Signup and view all the answers

    Which of the following is the primary source of heme for degradation?

    <p>Erythrocytes</p> Signup and view all the answers

    What is the final product of heme degradation?

    <p>Bilirubin</p> Signup and view all the answers

    What is the normal serum level of bilirubin?

    <p>2-17 micromolar</p> Signup and view all the answers

    Which condition can cause jaundice due to increased bilirubin levels?

    <p>Biliary obstruction</p> Signup and view all the answers

    What are the dietary sources of Vitamin B9 (Folate)?

    <p>Yeast and liver</p> Signup and view all the answers

    Which population is at risk of folate deficiency?

    <p>Pregnant women</p> Signup and view all the answers

    What are the symptoms of megaloblastic anemia?

    <p>Weakness and irritability</p> Signup and view all the answers

    What is the principal role of folate in the body?

    <p>Act as a single methyl group donor</p> Signup and view all the answers

    Which enzyme uses B12 as a cofactor in the synthesis of methionine from homocysteine?

    <p>Methionine synthase</p> Signup and view all the answers

    What is the net reaction catalyzed by methionine synthase?

    <p>Homocysteine + 5-methyl-THF → Methionine + THF</p> Signup and view all the answers

    What is the consequence of B12 deficiency on folate metabolism?

    <p>It inhibits the conversion of homocysteine to methionine</p> Signup and view all the answers

    Which of the following is a role of iron in metabolism?

    <p>Enzymes of drug metabolism and steroid synthesis</p> Signup and view all the answers

    What is the main form of stored iron in cells?

    <p>Ferritin</p> Signup and view all the answers

    Which of the following is a symptom of iron deficiency anemia?

    <p>Cold hands and feet</p> Signup and view all the answers

    What is the recommended daily intake of iron for men and women?

    <p>8-18 mg</p> Signup and view all the answers

    What facilitates the absorption of non-heme iron in the intestine?

    <p>Gastric acid and vitamin C</p> Signup and view all the answers

    Which condition can lead to iron overload?

    <p>Alcohol abuse</p> Signup and view all the answers

    What is the main role of folate in erythropoiesis?

    <p>DNA synthesis</p> Signup and view all the answers

    What condition can result from folate deficiency?

    <p>Megaloblastic anemia</p> Signup and view all the answers

    What are some dietary sources of folate?

    <p>Beans and spinach</p> Signup and view all the answers

    What is the main transporter for cobalamin in the blood?

    <p>Intrinsic factor</p> Signup and view all the answers

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