Methemoglobin and Blood Disorders
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Methemoglobin and Blood Disorders

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Questions and Answers

What is the role of hepcidin in iron metabolism?

  • Inactivates ferroportin (correct)
  • Increases iron absorption
  • Transports iron to tissues
  • Absorbs iron in enterocytes

    • Transferrin can bind only one molecule of iron at a time.

    False

    What triggers ferric iron to attach to transferrin?

    When the pH is 7.4

    Ferroportin is the only known protein that exports iron across ________.

    <p>cell membranes</p> Signup and view all the answers

    Match the components of iron transport with their functions:

    <p>Transferrin = Carries iron in the blood Hepcidin = Regulates iron absorption Ferroportin = Exports iron from cells Ferritin = Stores iron in cells</p> Signup and view all the answers

    What is anisocytosis?

    <p>Variation in red blood cell population size</p> Signup and view all the answers

    Megaloblastic erythropoiesis is caused by Vitamin B12 or Vitamin B9 (Folate) deficiency.

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

    What is the typical MCV range for normal red blood cells?

    <p>80-100 fL</p> Signup and view all the answers

    Microcytic red blood cells typically have an MCV of less than _____ fL.

    <p>80</p> Signup and view all the answers

    Match the following types of anemia to their causes:

    <p>Microcytic Anemia = Thalassemia Megaloblastic Anemia = Vitamin B12 Deficiency Iron-deficiency Anemia = Iron Deficiency Sideroblastic Anemia = Defective Protoporphyrin</p> Signup and view all the answers

    What is the role of Methemoglobin Reductase?

    <p>Converts ferric form of iron back to ferrous form</p> Signup and view all the answers

    Sulfhemoglobin is formed by the reversible oxidation of hemoglobin.

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

    List two exogenous sources of Sulfhemoglobin.

    <p>Automobile exhaust, industrial pollutants</p> Signup and view all the answers

    When hemoglobin is oxidized, the molecule changes and may form ______.

    <p>Heinz Bodies</p> Signup and view all the answers

    What can be a toxic effect of high levels of COHb?

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

    Match the drugs with their association to Sulfhemoglobin:

    <p>Sulfonamides = Drug linked to Sulfhemoglobin formation Phenacetin = Drug linked to Sulfhemoglobin formation Acetanilide = Drug linked to Sulfhemoglobin formation Phenazopyridine = Drug linked to Sulfhemoglobin formation</p> Signup and view all the answers

    What color does methemoglobin typically present?

    <p>Brownish to bluish</p> Signup and view all the answers

    Individuals with high COHb levels can experience polycythemia as a compensatory mechanism.

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

    Which condition is characterized by autoagglutination of red blood cells?

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

    Rouleaux formation occurs when red blood cells are stacked like coins.

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

    What is the main confirmatory test for hyperproteinemia indicated in the content?

    <p>Erythrocyte sedimentation rate (ESR)</p> Signup and view all the answers

    RBC clumping in cold temperatures is an example of __________.

    <p>Cold Agglutinin Disease</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Hyperproteinemia = Increased amount of globulin Autoagglutination = RBCs aggregate in individual’s plasma Rouleaux = Stacks of erythrocytes Erythrocyte sedimentation rate = Test to confirm hyperproteinemia</p> Signup and view all the answers

    Which substance hampers the formation of rouleaux?

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

    In autoagglutination, the individual RBCs cannot be outlined clearly.

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

    What morphology do normal red blood cells exhibit?

    <p>Non-nucleated, biconcave disc (discocyte)</p> Signup and view all the answers

    What is a characteristic of normal red blood cells?

    <p>They are uniform in size, shape, and hemoglobin concentration.</p> Signup and view all the answers

    True rouleaux formation is a significant factor in determining the Erythrocyte Sedimentation Rate (ESR).

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

    What are the diameters of normal red blood cells?

    <p>6-8 um</p> Signup and view all the answers

    Megaloblastic anemia is characterized by _____ red blood cells.

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

    Which condition is associated with microcytic red blood cells?

    <p>Both B and C</p> Signup and view all the answers

    The central pallor of a normal red blood cell constitutes half its diameter.

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

    Match the types of anemia with their corresponding categories:

    <p>Megaloblastic anemia = Macrocytic red blood cells Iron deficiency anemia = Microcytic red blood cells Thalassemia = Microcytic red blood cells Anemia of chronic disease = Microcytic red blood cells</p> Signup and view all the answers

    What is anisocytosis?

    <p>Variation in the size of red blood cells.</p> Signup and view all the answers

    Study Notes

    Methemoglobin Reductase

    • Methemoglobin is a form of hemoglobin that is unable to bind to oxygen
    • In methemoglobin, the iron atom in heme is in the ferric (Fe3+) state rather than the ferrous (Fe2+) state
    • Methemoglobin reductase is an enzyme that reduces ferric (Fe3+) iron back to the ferrous (Fe2+) state
    • This enzyme helps to maintain the normal function of hemoglobin

    Heinz Bodies

    • Heinz bodies are inclusions found within red blood cells
    • They are precipitated denatured hemoglobin
    • Heinz bodies are a result of oxidative damage to hemoglobin
    • They are formed by the precipitation of denatured hemoglobin within the red blood cell
    • The text mentions that Heinz bodies can decrease red blood cell survival

    Sulfhemoglobin

    • Sulfhemoglobin is a form of hemoglobin that is unable to bind to oxygen
    • It is formed by the irreversible oxidation of hemoglobin
    • It can be caused by exposure to certain drugs such to sulfonamides, phenacetin, acetanilide, and phenazopyridine
    • It can also be caused by exposure to environmental pollutants, such as industrial pollutants and tobacco smoke
    • Sulfhemoglobin has a lower affinity for oxygen than normal hemoglobin
    • Individuals with high levels of sulfhemoglobin are more susceptible to hypoxia

    Carbon Monoxide (CO)

    • Carbon monoxide (CO) binds to hemoglobin with a much higher affinity than oxygen
    • This prevents oxygen from binding to hemoglobin, leading to hypoxia
    • COHb levels can be as high as 15% in smokers

    Hemoglobin

    • Hemoglobin is a protein found in red blood cells
    • It is responsible for transporting oxygen throughout the body
    • Oxygen binds to the heme component of hemoglobin

    Iron Cycle and Transport

    • Transferrin is a protein that transports iron throughout the body
    • Iron is absorbed in the duodenum and jejunum
    • Iron is transported to bone marrow for red blood cell production
    • Iron is stored in the liver and spleen

    Hepcidin

    • Hepcidin is a hormone that regulates iron absorption
    • It is produced by the liver
    • Hepcidin binds to ferroportin, which is a protein that transports iron across cell membranes
    • Hepcidin reduces the absorption of iron
    • Hepcidin production is increased in high iron stores and decreased in low iron stores

    Transferrin Receptors

    • Transferrin receptors bind to transferrin, which is a protein that transports iron throughout the body
    • Transferrin receptors are found on the surface of red blood cell precursors in the bone marrow

    Ferritin

    • Ferritin is a protein that stores iron in the body
    • Ferritin can bind to ferric (Fe3+) iron
    • Ferritin is found in the liver, spleen, and other tissues

    Clinical Significance

    • Rouleaux formation is a stacking of red blood cells
    • It can be caused by increased levels of proteins in the blood, such as globulin and fibrinogen
    • Rouleaux formation is often seen in hyperproteinemia and multiple myeloma
    • When the text mentions "true rouleaux", it refers to rouleaux formation caused by increased levels of proteins in the blood
    • When it mentions "artifactual rouleaux" it is caused by a technical issue with the blood smear.
    • Autoagglutination is the clumping of red blood cells
    • It can be caused by autoantibodies, which are antibodies that attack the individual's own body
    • Autoagglutination is often seen in cold agglutinin disease, where red blood cells clump at cold temperatures

    Red Blood Cell Morphology

    • Red blood cells are normally biconcave discs (discocytes)
    • This shape is optimal for gas transport
    • Macrocytic red blood cells are larger than normal red blood cells
    • Macrocytosis is often seen in megaloblastic anemia
    • Microcytic red blood cells are smaller than normal red blood cells
    • Microcytosis is often seen in iron deficiency anemia, thalassemia, and sideroblastic anemia
    • Anisocytosis is the variation in red blood cell size
    • Anisocytosis is often seen in iron deficiency anemia
    • Oval macrocytes are oval-shaped red blood cells that are larger than normal red blood cells
    • Oval macrocytes are often seen in megaloblastic anemia
    • The text mentions that oval macrocytes have "markedly increased MCV"
    • MCV is the mean corpuscular volume, which is a measure of the average size of red blood cells

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    Description

    This quiz covers essential concepts related to methemoglobin and its effects on hemoglobin function. It explores the roles of methemoglobin reductase, the significance of Heinz bodies, and the formation of sulfhemoglobin. Test your understanding of these critical topics in hematology.

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