Blood 2

• What are white blood cells also called?

  Leukocytes
• What organelles do white blood cells have?

  They have nuclei and other organelles
• What do white blood cells lack?

  Hemoglobin
• What are the main functions of white blood cells?

  • Defending the body against pathogens
  • Removing toxins and wastes
  • Attacking abnormal or damaged cells
• Where are most white blood cells found?

  In connective tissue proper and organs of the lymphatic system
• How many white blood cells are typically found per microliter of blood?

  5000 to 10,000
• What are the characteristics of circulating white blood cells?

  • All can migrate out of the bloodstream
  • All are capable of amoeboid movement
  • All are attracted to specific chemical stimuli (positive chemotaxis)
  • Some are phagocytic
• What is a characteristic feature of neutrophils?

  They have a multilobed nucleus
• What are the two main types of white blood cells?

  • Granular leukocytes
  • Agranular leukocytes
• What percentage of circulating white blood cells are neutrophils?

  50–70 percent
• How long do neutrophils live in the bloodstream?

  10 hours or less
• What do the pale cytoplasmic granules in neutrophils contain?

  Lysosomal enzymes and bactericidal compounds
• What is pus composed of?

  A mixture of dead neutrophils and cellular debris
• What is degranulation in neutrophils?

  Reduction in the number of cytoplasmic granules
• What do neutrophils release during degranulation?

  Prostaglandins and leukotrienes
• What percentage of circulating white blood cells are eosinophils?

  2–4 percent
• What do eosinophils attack?

  Large parasites and allergens
• What do eosinophils release to reduce inflammation?

  Enzymes
• What percentage of circulating white blood cells are monocytes?

  2–8 percent
• What do monocytes become after entering peripheral tissues?

  Macrophages
• What is the role of macrophages?

  Aggressive phagocytes that engulf large pathogens
• What percentage of circulating white blood cells are basophils?

  Less than 1 percent
• What do basophils release to enhance local inflammation?

  Histamine and heparin
• What percentage of circulating white blood cells are lymphocytes?

  20–40 percent
• What are the classes of lymphocytes and their functions?

  • T cells: Responsible for cell-mediated immunity
  • B cells: Responsible for humoral immunity and produce antibodies
  • Natural killer (NK) cells: Responsible for immune surveillance
• Where are lymphocytes mostly found?

  In organs of the lymphatic system and connective tissues
• What is a differential count of white blood cells?

  Examining a blood smear to determine the percentage of each type of WBC
• What are the disorders related to white blood cells?

  • Leukopenia: Low WBC count
  • Leukocytosis: High WBC count
  • Leukemia: Cancer of the WBCs
• What is leukopoiesis?

  White blood cell production
• What do hemocytoblasts produce?

  Myeloid stem cells and lymphoid stem cells
• What do lymphoid stem cells give rise to?

  Lymphocytes
• What do myeloid stem cells give rise to?

  All formed elements except lymphocytes
• How do white blood cells develop?

  • Granulocytes complete development in red bone marrow
  • Monocytes become macrophages in peripheral tissues
  • B cells and NK cells complete development in bone marrow
  • T cells develop and mature in the thymus
• How is white blood cell production regulated?

  • Childhood and puberty: Hormones from the thymus regulate T cell production
  • Adults: B and T cell production regulated by exposure to antigens
  • Colony-stimulating factors (CSFs) regulate WBC populations
• What does multi-CSF do?

  Accelerates production of granulocytes, monocytes, platelets, and RBCs
• What does GM-CSF stimulate?

  The production of granulocytes and monocytes
• What does G-CSF stimulate?

  The production of granulocytes
• What does M-CSF stimulate?

  The production of monocytes
• How long do platelets circulate in the blood?

  9–12 days
• What are platelets and their functions?

  • Platelets (thrombocytes) are cell fragments involved in clotting
  • Functions:
  • Release chemicals important for clotting
  • Temporarily patch damaged vessel walls
  • Reduce the size of breaks in vessel walls