Haematology

• What is blood a component of?

  Cardiovascular system
• What is the average blood volume in an adult?

  5 litres
• What type of tissue is blood classified as?

  Fluid connective tissue
• What are the main components of blood?

  • Plasma (55%)
  • Red blood cells (45%)
  • White blood cells (<1%)
  • Platelets (<1%)
• What is the primary function of plasma?

  Transport molecules, formed elements, and heat
• What does blood transport?

  • Gases (O2 and CO2)
  • Nutrients
  • Excretory products
• What are the defense functions of blood?

  • Antibodies/white blood cells
  • Clotting factors
• What is haematopoiesis?

  • Formation of blood cells
  • Involves myeloid and lymphoid progenitors
• What are the two types of progenitors in haematopoiesis?

  • Myeloid progenitor
  • Lymphoid progenitor
• What is the definition of erythropoiesis?

  Formation of red blood cells
• What is a proerythroblast?

  Immature red blood cell in bone marrow
• What are the phases of erythrocyte development?

  1. Ribosome synthesis
  2. Hemoglobin accumulation
  3. Ejection of nucleus
• What are the requirements for erythropoiesis?

  • Erythropoietin (EPO)
  • Iron
  • Vitamins B12 and B9
  • Intrinsic factor
  • Amino acids
• Where does erythropoiesis occur in adults?

  Red bone marrow
• What are the structural features of red blood cells?

  • Flexible
  • Deform readily
  • Biconcave shape
  • Contain hemoglobin
• What is the life cycle of a red blood cell?

  120 days
• What happens to hemoglobin after red blood cell breakdown?

  • Heme breaks down into bilirubin
  • Transported to liver and secreted into bile
• What causes hypoxia?

  • Increase in exercise
  • High altitude
  • Smoking
  • Bleeding
• What is the function of hemoglobin?

  Transports oxygen from lungs to tissues
• What is the structure of adult hemoglobin (HbA)?

  • 4 subunits: 2 alpha, 2 beta
  • Contains heme bound to globin
  • Fe2+ ferrous iron atom in center
• What are the functions of hemoglobin?

  • Carriage of gases (O2, CO2, CO, H+)
• What is the definition of anemia?

  • Low hemoglobin concentration in blood
• What are the types of anemia?

  1. Iron deficiency anemia
  2. Megaloblastic anemia
  3. Sickle cell anemia
• What causes iron deficiency anemia?

  Pregnancy, bleeding, malabsorption
• What characterizes megaloblastic anemia?

  Vitamin B12 or folate deficiency
• What is the treatment for vitamin B12 deficiency?

  Vitamin B12 intramuscular injections
• What is sickle cell anemia associated with?

  Abnormal hemoglobin structure
• What are thalassemias?

  • Hereditary disorders
  • Abnormal hemoglobin production
  • A and B thalassemias
• What is haemostasis?

  • Process of blood clot formation
• What are the steps of haemostasis?

  1. Vasoconstriction of blood vessels
  2. Platelet adhesion and aggregation
  3. Clotting (coagulation phase)
• What are platelets?

  Small, oval, no nucleus cells
• What controls platelet production?

  • Number of circulating platelets
  • Thrombopoietin (TPO) release
• What are the important components of the coagulation phase?

  • Collagen exposure
  • Platelet activation
  • Serotonin for vasoconstriction
  • ADP for platelet aggregation
• What is the endpoint of the coagulation phase?

  • Conversion of fibrinogen to fibrin
• What initiates the coagulation phase?

  • Tissue damage releases tissue factor
• What is the common pathway in coagulation?

  1. Prothrombinase activates prothrombin to thrombin
  2. Thrombin converts fibrinogen to fibrin
• What role do calcium and vitamin K play in clotting?

  • Calcium is essential for clotting
  • Vitamin K is necessary for clotting factor production
• What is fibrinolysis?

  • Breakdown of fibrin clot
  • Plasmin enzyme involved
• What are blood groups based on?

  • Combinations of surface antigens on red blood cells
• What are the most clinically significant blood group systems?

  • ABO and Rh blood group systems