Hemopiesis

• What percentage of a 70 kg person's total weight is constituted by blood?

  About 7%
• How does blood flow through the body?

  Blood flows from the heart into arteries, then to capillaries, and returns to the heart through veins.
• What is the composition of blood in terms of liquid plasma and cells?

  Blood is composed of 52–62% liquid plasma and 38–48% cells.
• What is the primary component of plasma?

  Plasma is mostly water (91.5%).
• What are the main types of proteins found in blood plasma?

  Albumins, globulins, and fibrinogen.
• What is the pH level of blood?

  The pH of blood is 7.40 ± 0.05.
• What is the density of blood?

  The density of blood is 1.057 ± 0.009.
• Where are all blood cells manufactured?

  All blood cells are manufactured by stem cells in the bone marrow.
• What are the three types of blood cells produced from hemocytoblasts?

  Erythrocytes, leukocytes, and thrombocytes.
• How are leukocytes further subdivided?

  Leukocytes are subdivided into granulocytes and agranulocytes.
• What are the types of granulocytes?

  Neutrophils, eosinophils, and basophils.

  
• What is the lifespan of leukocytes?

  Leukocytes live for 5-9 days.
• How many red blood cells are produced each second?

  About 2,400,000 RBCs are produced each second.
• What is the lifespan of red blood cells?

  Red blood cells live for about 120 days.
• What is the normal count of red blood cells per mm³ in a healthy male?

  About 5 million RBCs per mm³.
• What is the normal adult blood cell count for leukocytes?

  About 7.3*10³/mm³.
• What are the normal adult blood cell counts for different types of blood cells?

  • Red Blood Cells: 5.0*10^6/mm³
  • Platelets: 2.5*10^5/mm³
  • Leukocytes: 7.3*10^3/mm³
• What is hematopoiesis?

  Hematopoiesis is the process through which the body manufactures blood cells.
• When does hematopoiesis begin in human development?

  Hematopoiesis begins early in the development of an embryo, well before birth.
• Where does primitive hematopoiesis occur in the embryo?

  Primitive hematopoiesis occurs in the yolk sac.
• What organs are involved in hematopoiesis as the embryo develops?

  The liver, spleen, and bone marrow are involved in hematopoiesis as the embryo develops.
• Where does hematopoiesis primarily occur in adults?

  Hematopoiesis of red blood cells and platelets occurs primarily in the bone marrow.
• What type of white blood cell is produced by the lymph system?

  The lymph system produces lymphocytes.
• What are the three broad categories of blood cell types?

  Red blood cells, white blood cells, and platelets.

  
• What are the functions of different types of white blood cells?

  • Lymphocytes: Fight viruses and tumors.
  • Neutrophils: Fight bacterial and fungal infections.
  • Eosinophils: Play a role in inflammatory response and fight parasites.
  • Basophils: Release histamines for inflammatory response.
  • Macrophages: Engulf and digest debris, including bacteria.
• What is the monophyletic theory of hematopoiesis?

  The monophyletic theory states that one type of stem cell produces all types of blood cells.
• What does erythropoiesis produce?

  Erythropoiesis produces red blood cells (erythrocytes).
• How many red blood cells does the body produce on average per kg per day?

  The body produces about 2.5 billion red blood cells per kg per day.
• Where does erythropoiesis occur in the early fetus?

  Erythropoiesis occurs in the yolk sac in the early fetus.
• At what stage does erythropoiesis establish in the bone marrow?

  Erythropoiesis establishes in the bone marrow from about 5 months’ gestation.
• In which bones does erythropoiesis occur in adults?

  Erythropoiesis occurs in the vertebrae, ribs, sternum, sacrum, pelvis, and proximal femur in adults.
• What triggers extramedullary hematopoiesis?

  Extramedullary hematopoiesis is triggered when erythropoiesis is inadequate in the bone marrow.
• What are the stages of erythropoiesis?

  The stages of erythropoiesis include becoming normoblasts, maturing into reticulocytes, and finally maturing into erythrocytes.
• What is nuclear extrusion in erythropoiesis?

  Nuclear extrusion is when mature erythrocytes have no nucleus.
• What regulates erythropoiesis?

  Erythropoiesis is mainly driven by the hormone erythropoietin (EPO).
• Where is erythropoietin secreted?

  Erythropoietin is secreted by the kidney.
• What happens when erythrocyte levels become inadequate?

  The blood becomes relatively hypoxic when erythrocyte levels become inadequate.
• How does the feedback loop of erythropoiesis work?

  Inadequate erythrocyte levels lead to increased EPO production, stimulating red blood cell production, which raises hemoglobin levels and pO2, causing EPO levels to fall.
• What is the foundation of laboratory hematologic diagnosis?

  The foundation of laboratory hematologic diagnosis is the complete blood count and review of the peripheral smear.
• What does the peripheral smear allow in patients with anemia?

  The peripheral smear permits interpretation of diagnostically significant red blood cell findings.