Red Blood Cell Structure and Function
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Questions and Answers

What is the primary function of the erythrocyte?

  • To undergo oxidative phosphorylation
  • To reproduce and divide into new cells
  • To transport oxygen to tissues (correct)
  • To produce stem cells in the bone marrow

    • What is the average lifespan of a red blood cell in adults?

  • 180 days
  • 60 days
  • 120 days (correct)
  • 90 days

    • What is the primary factor that governs erythropoiesis?

  • Kidney function
  • Oxygen content of blood
  • Hemoglobin levels
  • Tissue oxygen needs (correct)

    • What is the hormone produced by the kidneys in response to decreased oxygen content?

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

    In which part of the body does red cell production primarily take place beyond 20 years of age?

    <p>Bones of the vertebra, sternum, ribs, and pelvis</p> Signup and view all the answers

    What is the term for the production of red cells?

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

    What is the iron-containing substance in hemoglobin?

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

    How many hemoglobin molecules are present in each RBC?

    <p>300</p> Signup and view all the answers

    What is the characteristic of a mature red blood cell?

    <p>It is a non-nucleated, biconcave disk</p> Signup and view all the answers

    What is the pair of chains in fetal hemoglobin?

    <p>Alpha and gamma chains</p> Signup and view all the answers

    What is the stage of development of red cells that enter the blood?

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

    What is the reason for the biconcave disk shape of the red blood cell?

    <p>To increase the surface area for diffusion of oxygen</p> Signup and view all the answers

    What is the result of alterations in genes on hemoglobin?

    <p>Abnormal hemoglobin</p> Signup and view all the answers

    What is the primary function of erythropoietin?

    <p>To stimulate RBC production</p> Signup and view all the answers

    What is the approximate age at which fetal hgb converts to adult hgb?

    <p>4-6 months</p> Signup and view all the answers

    What is the function of the iron atom in the heme unit of hemoglobin?

    <p>It binds to oxygen</p> Signup and view all the answers

    What is a potential consequence of genetic mutations affecting hemoglobin protein formation?

    <p>Formation of abnormal hemoglobin molecules</p> Signup and view all the answers

    What is necessary for red blood cell survival?

    <p>Intact bone marrow and functional erythropoietin</p> Signup and view all the answers

    What happens to the hemoglobin released into the circulation when a red blood cell disintegrates at the end of its lifespan?

    <p>It is broken down in the liver and spleen</p> Signup and view all the answers

    What is the fate of the iron and globin components of hemoglobin after it is broken down?

    <p>They are salvaged and reused</p> Signup and view all the answers

    What is the final product of hemoglobin breakdown that is excreted in the stool?

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

    What is the normal rate of destruction of red blood cells per day?

    <p>1% per day</p> Signup and view all the answers

    What is the normal range of reticulocytes in relation to total RBCs?

    <p>1-2% of total RBCs</p> Signup and view all the answers

    What is the normal range of hematocrit for men?

    <p>41-50% of total blood volume</p> Signup and view all the answers

    What is the suffix that refers to the size of red blood cells?

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

    What is the normal range of hemoglobin in grams per 100ml of blood for women?

    <p>12-16 g/dl</p> Signup and view all the answers

    What is the term that describes the percentage of blood that is taken up by red blood cells?

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

    What is the normal range of red blood cells in millions?

    <p>4.2-5.4 million</p> Signup and view all the answers

    What is the normal range of Mean Corpuscular Volume (MCV)?

    <p>87-103 fl/red cell</p> Signup and view all the answers

    What is the normal range of Mean Corpuscular Hemoglobin Concentration (MCHC)?

    <p>31-35 g/dl</p> Signup and view all the answers

    What is the maximum concentration of hemoglobin in a red blood cell?

    <p>37 g/dl</p> Signup and view all the answers

    What is anemia?

    <p>An indication of some disease process or alteration in body function that results in a deficiency in red cells or hemoglobin</p> Signup and view all the answers

    What is the definition of anemia in men according to the World Health Organization (WHO)?

    <p>Hemoglobin &lt; 13.0 gm/dl, hematocrit &lt; 42%</p> Signup and view all the answers

    What is the term for the production of red cells?

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

    What can cause anemia?

    <p>Excessive loss, increased destruction, or impaired production of red cells or hemoglobin</p> Signup and view all the answers

    What is the term for red blood cells that are too small in size?

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

    What is the term for red blood cells with too little hemoglobin?

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

    Study Notes

    Red Blood Cells (RBC)

    • Mature RBCs, or erythrocytes, are non-nucleated, biconcave disks, lacking mitochondria and ribosomes.
    • RBCs have a lifespan of approximately 120 days in adults and 90 days in infants; can be as short as 2-10 days in hemolytic anemias (e.g., sickle cell disease).
    • The biconcave shape increases surface area for oxygen diffusion and allows flexibility without membrane rupture.

    Erythropoiesis

    • Erythropoiesis is the process of red blood cell production.
    • All RBCs are produced in red bone marrow at birth, with production shifting to selective bones after age 5, and to vertebra, sternum, ribs, and pelvis by age 20.
    • RBC precursors, erythroblasts, develop from stem cells, reducing in size as they mature; they accumulate hemoglobin and lose their nucleus.
    • Red cells initially enter the bloodstream as reticulocytes and mature into erythrocytes.
    • Fetal hemoglobin transitions to adult hemoglobin around 4-6 months of age.
    • Hemoglobin consists of four polypeptide chains associated with heme units that bind oxygen; each molecule can carry four oxygen molecules.

    Genetic Mutations

    • Genetic variations can lead to abnormal hemoglobin formation (e.g., sickle cell disease) or inadequate synthesis of alpha or beta chains (e.g., thalassemia), contributing to anemia.

    Factors Affecting RBC Survival

    • Survival relies on intact bone marrow responsive to erythropoietin.
    • Functional erythropoietin from kidneys is essential.
    • Sufficient DNA components (folic acid, vitamin B12) are necessary for RBC integrity.
    • Adequate hemoglobin synthesis depends on iron and globin availability.

    RBC Destruction

    • At the end of their lifespan, RBCs disintegrate, releasing hemoglobin, which is broken down in the liver and spleen.
    • Hemoglobin decomposes into iron and globin, which are reused, while bilirubin is formed and excreted in bile or urine.
    • Typical destruction and production rates balance at about 1% of RBCs per day.

    Laboratory Evaluation

    • Normal RBC count ranges from 4.2-5.4 million cells per microliter.
    • Reticulocyte levels indicate production rates, with a normal rate of approximately 1-2% of total RBCs.
    • Hemoglobin levels vary: 13.5-17.5 g/dL for men and 12-16 g/dL for women.
    • Hematocrit measures the volume percentage of blood occupied by RBCs, generally between 36-50%.

    Red Cell Indices

    • Used for diagnosing types of anemia based on cell size and hemoglobin content.
    • "Cytic" refers to cell size, while "chromic" addresses hemoglobin concentration.
    • Mean Corpuscular Volume (MCV) identifies cell size; ranges: normocytic (87-103 fL), microcytic (less than 80 fL).
    • Mean Corpuscular Hemoglobin Concentration (MCHC) indicates hemoglobin concentration; normal range is 31-35 g/dL.

    Anemia Definition

    • Anemia reflects an underlying disease or body function alteration resulting in insufficient RBCs or hemoglobin.
    • Causes include excessive blood loss, hemolytic disorders causing increased destruction, or impaired production due to deficiencies (e.g., iron, B12, folate).
    • WHO defines anemia thresholds: hemoglobin < 13.0 g/dL or hematocrit < 42% for men; hemoglobin < 12.0 g/dL for women.

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    Description

    Learn about the characteristics and functions of mature red blood cells, including their unique shape, lack of nucleus and organelles, and role in oxygen transport. Understand how their structure allows them to change shape without rupturing their membrane and perform their vital function.

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