Hematology Lecture 1
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Questions and Answers

What is the primary function of albumin in plasma?

  • Maintaining osmotic pressure (correct)
  • Transporting nutrients
  • Acting as an antibiotic
  • Facilitating clotting

    • During which trimester does the liver primarily contribute to haemopoiesis?

  • First trimester
  • Second trimester (correct)
  • Third trimester
  • Postnatal period

    • What percentage of the total solids in plasma do plasma proteins account for?

  • 70% (correct)
  • 80%
  • 60%
  • 50%

    • What is the main component of the buffy coat in centrifuged blood?

    <p>White blood cells</p> Signup and view all the answers

    Which of the following best describes serum?

    <p>Liquid without clotting factors</p> Signup and view all the answers

    Where does haemopoiesis primarily occur during the third trimester and throughout life?

    <p>Bone marrow</p> Signup and view all the answers

    Which of the following best characterizes haemopoietic stem cells?

    <p>Capable of replication into multiple blood cell types</p> Signup and view all the answers

    What is the likely outcome if blood is collected into a tube containing no anticoagulant?

    <p>It forms a clot, leaving serum above</p> Signup and view all the answers

    What is the percentage of reticulocytes normally found in the blood?

    <p>2.5%</p> Signup and view all the answers

    Which type of hemoglobin has the highest affinity for oxygen?

    <p>Fetal hemoglobin (Hb F)</p> Signup and view all the answers

    What leads to an increased reticulocyte count in the peripheral blood?

    <p>Acute hemorrhage</p> Signup and view all the answers

    What percentage of oxygen can each gram of pure hemoglobin combine with?

    <p>1.34 milliliters</p> Signup and view all the answers

    What is the primary globin chain composition of adult hemoglobin (Hb A)?

    <p>2α and 2β chains</p> Signup and view all the answers

    What happens to the iron from the degraded heme portion after red blood cell destruction?

    <p>It is taken by plasma transferrin to be reused for RBC synthesis.</p> Signup and view all the answers

    Which enzyme catalyzes the reversible reaction between CO2 and water to form carbonic acid?

    <p>Carbonic anhydrase</p> Signup and view all the answers

    Which type of hemoglobin is normally present at very low concentrations in adults?

    <p>Hemoglobin A2</p> Signup and view all the answers

    What is the normal hemoglobin concentration range in women?

    <p>12-15 g/dl</p> Signup and view all the answers

    What occurs to red blood cells at the end of their life span?

    <p>They are destroyed by macrophages in the reticuloendothelial system.</p> Signup and view all the answers

    What structure forms the core of each heme group in hemoglobin?

    <p>Protoporphyrin ring</p> Signup and view all the answers

    How many iron atoms are there in each hemoglobin molecule?

    <p>4</p> Signup and view all the answers

    What compound is formed from the breakdown of the protoporphyrin ring in hemoglobin?

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

    What is the earliest recognized erythroid precursor in the bone marrow?

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

    How does hemolytic anemia typically affect bilirubin levels in the body?

    <p>Indirect bilirubin is elevated, causing jaundice.</p> Signup and view all the answers

    What is the role of regulatory factors in stem cell biology?

    <p>They promote the self-renewal and differentiation of stem cells.</p> Signup and view all the answers

    What is the predominant cause of RBC death as they age?

    <p>Gradual degradation of enzymes without replacement.</p> Signup and view all the answers

    In which anatomical location does haemopoiesis primarily occur after three months of intrauterine life?

    <p>In the bone marrow</p> Signup and view all the answers

    What change occurs in bone marrow from newborns to elderly individuals?

    <p>The amount of red bone marrow decreases while yellow marrow increases.</p> Signup and view all the answers

    Which stem cell type does not possess self-renewal capabilities?

    <p>Precursor cells</p> Signup and view all the answers

    What characterizes the transition from pluripotent stem cells to myeloid and lymphoid stem cells?

    <p>The influence of growth factors causing cell separation.</p> Signup and view all the answers

    What is the main function of the stroma in red bone marrow?

    <p>It provides structural support and a supportive environment for hematopoietic cells.</p> Signup and view all the answers

    Which substance is NOT typically found in the composition of red bone marrow?

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

    How is yellow bone marrow converted back to red bone marrow?

    <p>In response to conditions like severe bleeding or hypoxia.</p> Signup and view all the answers

    What structural features define sinusoidal capillaries?

    <p>A discontinuous layer of endothelial cells and reticular fibers.</p> Signup and view all the answers

    What is the primary reason that erythrocytes can easily pass through small capillary pores?

    <p>Their flexibility and lack of a nucleus facilitate shape change.</p> Signup and view all the answers

    What differentiates integral proteins from peripheral proteins in the RBC membrane?

    <p>Integral proteins span the membrane, while peripheral proteins are found only on the inner surface.</p> Signup and view all the answers

    Which statement correctly describes hemoglobin in relation to erythrocytes?

    <p>It is the main protein in RBCs, accounting for over 95% of their dry weight.</p> Signup and view all the answers

    What process describes the series of developmental stages leading to mature RBCs?

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

    Which of the following is a characteristic of pro-erythroblasts?

    <p>They produce hemoglobin until maturity.</p> Signup and view all the answers

    What happens to the nucleus of an erythrocyte as it matures?

    <p>It gets progressively smaller and is eventually extruded.</p> Signup and view all the answers

    What percentage of the RBC membrane's composition is made up of carbohydrates?

    <p>10%</p> Signup and view all the answers

    Study Notes

    Hematology Lecture (1)

    • Blood is a liquid connective tissue
    • It's composed of two parts: formed elements (blood cells) and plasma
    • Formed elements include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
    • Plasma is the liquid in which the formed elements are suspended
    • It's an aqueous solution composed of 90% water and 10% solids (solutes)
    • Plasma proteins account for 70% of the total solids
    • Albumin is the most abundant plasma protein and maintains osmotic pressure of the blood
    • The hematocrit (PCV) estimates the volume of packed erythrocytes per unit volume of blood
    • If blood is collected without an anticoagulant, it clots, separating into a clot containing formed elements and a clear yellow liquid called serum
    • If blood is collected with an anticoagulant, it will not clot and when centrifuged separates into three layers:
      • Lower layer (red): erythrocytes (about 40-45%)
      • Middle layer (white): buffy coat (WBCs and platelets) (about 1%)
      • Upper layer (translucent/yellowish): plasma (about 55%)

    Haemopoiesis

    • It's the process of forming new blood cells from hematopoietic stem cells
    • Sites of haemopoiesis:
      • First trimester: yolk sac
      • Second trimester: mainly liver, with spleen and lymph nodes contributing
      • Third trimester and later: bone marrow
    • A graph shows relative contributions of yolk sac, liver, and bone marrow over time

    Stem Cells

    • These are the cells from which all hematopoietic cells originate
    • Characteristics: self-renewal and differentiation
    • Requirements for proliferation and differentiation: regulatory factors (Hemopoietic Growth Factors) and a suitable microenvironment (marrow space)
    • Earliest stem cell is pluripotent, capable of producing all types of blood cells
    • Pluripotent stem cells differentiate into:
      • Myeloid multipotent stem cells
      • Lymphoid multipotent stem cells
    • Differentiation leads to production of mature blood cells

    RBC Production (Erythropoiesis)

    • RBCs are produced from pluripotent stem cells that develop into myeloid multipotent stem cells
    • Stages in erythropoiesis:
      • proerythroblast
      • basophilic normoblast
      • polychromatic normoblast
      • orthochromatic normoblast
      • reticulocyte
      • erythrocyte
    • Proerythroblast is the earliest precursor, only producing RBCs and goes through intermediate forms
    • During differentiation, cells become progressively more committed until they only produce one type of mature cell
    • Precursors lack self-renewal capacity and are restricted to one lineage
    • The proerythroblast is the earliest identified precursor of the RBC. (It only produces RBCs, not other blood components)
    • RBCs mature and accumulate hemoglobin until they reach 34%.
    • The nucleus is expelled, forming reticulocytes which contain residual RNA
    • Reticulocytes are released into the blood and develop into mature erythrocytes within 1 to 2 days
    • Normal reticulocyte count is typically less than 2.5% of total RBCs

    RBC Function

    • Carry oxygen from lungs to tissues via hemoglobin
    • Hemoglobin combines with 1.34 milliliters of oxygen per gram
    • Transport CO2 from tissues to lungs as bicarbonate ions (HCO3-)
    • Carbonic anhydrase catalyzes the reversible reaction between CO2 and water to form carbonic acid (H2CO3)
    • Hemoglobin plays a role in maintaining acid-base balance

    Hemoglobin Structure and Function

    • Normal hemoglobin concentration: 13-17 g/dL (men), 12-15 g/dL (women)
    • Hemoglobin production starts in the proerythroblast stage of RBC development; continues into the reticulocyte stage but stops at the mature stage.
    • Hemoglobin molecule consists of four heme groups, each with an iron atom capable of binding four oxygen molecules
    • Different forms of hemoglobin exist (embryonic, fetal, adult hemoglobin A, adult hemoglobin A2) varying in globin chain composition
    • These differences affect oxygen affinity

    Life Span and Destruction of RBCs

    • Lifespan is about 120 days
    • Destroyed by macrophages in spleen, liver, and bone marrow
    • No nucleus, cellular metabolism progressively deteriorates, becoming non-viable after 120 days
    • Hemoglobin is phagocytosed immediately by macrophages
    • Iron from hemoglobin is taken up by transferrin, primarily going to the bone marrow, for usage in new RBC synthesis
    • The protoporphyrin ring is degraded, converting to bilirubin. Liver conjugates and excretes as stercobilin
    • The stercobilin is excreted into the feces and some goes into the bloodstream where it is converted to urobilin and is excreted in the urine

    Fate of Hb after RBC Destruction

    • The heme portion of hemoglobin breaks down into iron, that is taken up by transferrin and reused; and protoporphyrin which is converted into bilirubin, conjugated, excreted into bile then as stercobilin into the feces.
    • Stercobilin and some bilirubin are reabsorbed into the bloodstream and converted to urobilinogen and finally into urobilin which is excreting the urine.
    • Globin chains are broken down to amino acids used for general protein synthesis in the body.

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    Hematology Lecture (1) PDF

    Description

    Explore the essential components of blood, including its composition and the roles of red blood cells, white blood cells, and plasma. This lecture provides insights into hematocrit and the effects of anticoagulants on blood samples. Gain a foundational understanding of this vital liquid connective tissue.

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