Blood Cells and Erythropoiesis
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Questions and Answers

What is the approximate number of new erythrocytes produced daily by the process of erythropoiesis?

  • 10^12 (correct)
  • 10^10
  • 10^9
  • 10^11

    • What is the function of red cells in the body?

  • To produce antibodies against infections
  • To regulate blood pressure
  • To carry oxygen from the lungs to the tissues and carbon dioxide in the reverse direction (correct)
  • To fight against bacterial and fungal infections

    • What is the lifespan of red cells in the circulation?

  • 4 months (correct)
  • 6 months
  • 1 month
  • 1 year

    • What is the function of platelets in the body?

    <p>To participate in haemostasis</p> Signup and view all the answers

    What is the name of the first recognizable erythrocyte precursor in the bone marrow?

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

    What is the characteristic of the pronormoblast?

    <p>Large cell with dark blue cytoplasm</p> Signup and view all the answers

    What is the function of monocytes in the body?

    <p>To protect against bacterial and fungal infections</p> Signup and view all the answers

    What is the name of the microenvironment in which erythropoiesis occurs?

    <p>Erythroid niche</p> Signup and view all the answers

    In patients with severe anaemia, what is the haemoglobin level associated with the adaptation shown in Figure 2.15?

    <p>Less than 90 g/L</p> Signup and view all the answers

    What is a reliable sign of anaemia?

    <p>Pallor of the conjunctival mucosa</p> Signup and view all the answers

    What is associated with a hyperdynamic circulation in anaemia?

    <p>Tachycardia and a bounding pulse</p> Signup and view all the answers

    What is a specific sign of iron deficiency anaemia?

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

    What is the most useful classification of anaemia?

    <p>Based on red cell indices</p> Signup and view all the answers

    What is the MCV range for microcytic anaemia?

    <p>Less than 95 fL</p> Signup and view all the answers

    What is associated with congestive heart failure in anaemia?

    <p>Features of anaemia in the elderly</p> Signup and view all the answers

    What is a specific sign of thalassaemia major?

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

    What is the primary function of neutrophils in the body?

    <p>Protection from bacteria and fungi</p> Signup and view all the answers

    What is the average lifespan of red cells in the blood?

    <p>120 days</p> Signup and view all the answers

    What is the function of natural killer cells?

    <p>Protection against virus-infected and neoplastic cells</p> Signup and view all the answers

    What is the diameter of platelets in the blood?

    <p>0.5-3.0 μm</p> Signup and view all the answers

    What is the process by which the nucleus is finally extruded from the late normoblast within the marrow?

    <p>Reticulocyte formation</p> Signup and view all the answers

    What is the primary function of basophils in the body?

    <p>Protection against parasites</p> Signup and view all the answers

    What is the function of lymphocytes in the body?

    <p>Immunoglobulin synthesis and protection against viruses</p> Signup and view all the answers

    What is the average lifespan of platelets in the blood?

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

    What is the process by which the automated cell counter detects abnormal cells?

    <p>Flow cytometry</p> Signup and view all the answers

    What is the function of eosinophils in the body?

    <p>Protection against parasites</p> Signup and view all the answers

    What is the role of PHD2 in regulating HIF-1α?

    <p>It hydroxylates HIF-1α, allowing VHL binding</p> Signup and view all the answers

    What is the underlying cause of congenital polycythaemia?

    <p>Mutations in VHL, PHD2, or HIF-1α</p> Signup and view all the answers

    What is the role of GATA2 in erythropoiesis?

    <p>It initiates erythroid differentiation from pluripotential stem cells</p> Signup and view all the answers

    What is the effect of erythropoietin receptor stimulation on GATA1 and FOG1?

    <p>It activates GATA1 and FOG1, enhancing erythroid-specific genes</p> Signup and view all the answers

    What is the indication for recombinant erythropoietin therapy?

    <p>End-stage renal disease</p> Signup and view all the answers

    What is the frequency of recombinant erythropoietin administration?

    <p>Three times weekly, once every 1-2 weeks, or every 4 weeks</p> Signup and view all the answers

    What is the role of the transferrin receptor (CD71) in erythropoiesis?

    <p>It is expressed on the surface of erythroid cells and enhances iron uptake</p> Signup and view all the answers

    What is the effect of erythropoietin on late BFUE and CFUE?

    <p>It stimulates their proliferation, differentiation, and haemoglobin production</p> Signup and view all the answers

    What is the primary function of haemoglobin in the red cells?

    <p>To carry O2 from the lungs to the tissues</p> Signup and view all the answers

    What is the result of the movement of the β chains in the haemoglobin molecule when O2 is unloaded?

    <p>The β chains are pulled apart, permitting entry of 2,3-DPG</p> Signup and view all the answers

    What is the effect of increased affinity of haemoglobin for O2 on the haemoglobin oxygen dissociation curve?

    <p>The curve shifts to the left</p> Signup and view all the answers

    What is the normal range of O2 saturation in venous blood?

    <p>70%</p> Signup and view all the answers

    What is the P50 of normal blood?

    <p>26.6 mmHg</p> Signup and view all the answers

    What is the effect of decreased affinity of haemoglobin for O2 on the haemoglobin oxygen dissociation curve?

    <p>The curve shifts to the right</p> Signup and view all the answers

    What is the purpose of the α1β1 and α2β2 contacts in the haemoglobin molecule?

    <p>To stabilize the molecule</p> Signup and view all the answers

    What is the normal range of O2 tension in venous blood?

    <p>40 mmHg</p> Signup and view all the answers

    What is the effect of increased red cell mass or increased O2 delivery to tissues on erythropoietin drive?

    <p>It reduces the erythropoietin drive</p> Signup and view all the answers

    What is the effect of a low serum erythropoietin level prior to treatment on the response to recombinant erythropoietin therapy?

    <p>It predicts an effective response to therapy</p> Signup and view all the answers

    What is the effect of administering recombinant erythropoietin therapy on the quality of life in patients with anaemia?

    <p>It improves the quality of life</p> Signup and view all the answers

    What is the anatomical change that occurs in the marrow in infants with chronic anaemia?

    <p>The marrow cavity expands into cortical bone</p> Signup and view all the answers

    What is the effect of recombinant erythropoietin therapy on the haemoglobin level in patients with anaemia?

    <p>It increases the haemoglobin level</p> Signup and view all the answers

    What is the potential side effect of recombinant erythropoietin therapy on tumours that express EPO receptors?

    <p>It accelerates the growth of the tumour</p> Signup and view all the answers

    What is the effect of administering recombinant erythropoietin therapy on blood pressure?

    <p>It increases blood pressure</p> Signup and view all the answers

    What is the effect of iron deficiency on erythropoiesis?

    <p>It inhibits erythropoiesis</p> Signup and view all the answers

    What is the effect of cobalt deficiency on erythropoiesis?

    <p>It inhibits erythropoiesis</p> Signup and view all the answers

    What is the effect of vitamin B12 deficiency on erythropoiesis?

    <p>It inhibits erythropoiesis</p> Signup and view all the answers

    Study Notes

    Erythropoiesis and Blood Cells

    • Erythropoiesis is the process of producing approximately 10^12 new erythrocytes (red blood cells) daily, regulated by a complex process involving stem cells, progenitor cells, and colony-forming units.
    • Blood cells derive from pluripotential stem cells in the bone marrow, dividing into three main types: red cells, platelets, and white cells.
    • Red cells, specialized for oxygen and carbon dioxide transport, have a 4-month lifespan and are produced through a process involving pronormoblasts, normoblasts, and reticulocytes.

    White Blood Cells

    • White cells, comprised of four types of phagocytes (neutrophils, eosinophils, basophils, and monocytes) and lymphocytes, have a wide range of lifespans.
    • Neutrophils, eosinophils, basophils, and monocytes are involved in protection against bacterial and fungal infections, parasites, and viral infections.
    • Lymphocytes, including B cells and T cells, are involved in antibody production, immune responses, and protection against viral infections.

    Cell Counting and Measurement

    • Automated cell counters measure red cell and platelet counts, as well as diameter and other parameters.
    • Flow cytometry detects and enumerates different types of white cells and detects abnormal cells.

    Erythropoietin and Anaemia

    • Erythropoietin, a hormone secreted by the kidneys, stimulates erythropoiesis and is essential for red blood cell production.
    • Recombinant erythropoietin is used to treat anaemia resulting from renal disease or other causes.

    Haemoglobin Structure and Function

    • Haemoglobin is a tetramer of four globin chains, each with its own haem group, and is responsible for oxygen transport.
    • The haemoglobin oxygen dissociation curve shows the relationship between oxygen saturation and partial pressure of oxygen.
    • 2,3-Diphosphoglycerate (2,3-DPG) affects the affinity of haemoglobin for oxygen, shifting the curve to the right or left.

    Anaemia

    • Anaemia is characterized by a low haemoglobin level (<90 g/L), resulting in symptoms such as fatigue, pallor, and shortness of breath.
    • The classification of anaemia is based on red cell indices, dividing into microcytic, normocytic, and macrocytic anaemias.
    • Specific signs are associated with particular types of anaemia, such as koilonychia with iron deficiency or jaundice with haemolytic or megaloblastic anaemias.

    Erythropoietin and Haemoglobin Production

    • Erythropoietin (EPO) is a key factor in the production of haemoglobin, which combines with iron to form haem.
    • The relationship between EPO and haemoglobin concentration is shown in Figure 2.6, where EPO levels in plasma are correlated with haemoglobin concentrations.

    Clinical Indications for Erythropoietin

    • Erythropoietin therapy is indicated for:
      • Anaemia of chronic renal disease
      • Myelodysplastic syndrome
      • Anaemia associated with malignancy and chemotherapy
      • Anaemia of chronic diseases
    • The main indication is end-stage renal disease, with or without dialysis.

    Erythropoietin Receptor Stimulation

    • Erythropoietin receptor stimulation activates transcription factors GATA1 and FOG1, which are important in enhancing expression of erythroid-specific genes.
    • These genes include globin, haem biosynthetic and red cell membrane proteins.
    • Erythropoietin receptor stimulation also enhances expression of anti-apoptotic genes and the transferrin receptor (CD71).

    Erythropoiesis

    • Late BFUE and CFUE, which have erythropoietin receptors, are stimulated to proliferate, differentiate, and produce haemoglobin.
    • The proportion of erythroid cells in the marrow increases, and in the chronic state, there is anatomical expansion of erythropoiesis into fatty marrow and sometimes into extramedullary sites.

    Marrow Requirements

    • The marrow requires many other precursors for effective erythropoiesis, including:
      • Metals such as iron and cobalt
      • Vitamins (especially vitamin B12, folate, vitamin C, and vitamin E)

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    Description

    Learn about the process of erythropoiesis, the formation of red blood cells and general aspects of anemia. Understand how blood cells derive from stem cells in the bone marrow.

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