L3.2.2: Leukocytes

• LEUKOCYTES

  ● White Blood Cells (WBCs)

  ● Crucial in the body’s defense against disease

  ● Complete cells with nucleus and organelles
• LEUKOCYTES

  ● Able to move into and out of blood vessels (diapedesis)

  ● Respond to chemicals released by damaged tissues (positive chemotaxis)

  ● Moved by amoeboid motion by forming cytoplasmic extensions to help them move

  ● 4,800 to 10,800 WBCs per mm3 of blood
• HOMEOSTATIC IMBALANCES

  ● Leukocytosis

  ● Leukopenia

  ● Leukemia
• HOMEOSTATIC IMBALANCES

  ● Leukocytosis

  ○ Normal response to an infection, but excessive production of normal WBCs during infectious mononucleosis or leukemia is pathological
• HOMEOSTATIC IMBALANCES

  ● Leukopenia

  ○ “Penia” = deficiency

  ○ Abnormally low WBC count

  ○ Commonly caused by certain drugs, such as corticosteroids and anticancer agents
• HOMEOSTATIC IMBALANCES

  ● Leukemia

  ○ Bone marrow becomes cancerous

  ○ Numerous immature WBC are produced
• TYPES OF LEUKOCYTES

  ● Granulocytes

  ● Agranulocytes

  ● Mnemonic for the most to least abundant WBC: Never Let Monkeys Eat Bananas

  ○ Neutrophils

  ○ Lymphocytes

  ○ Monocytes

  ○ Eosinophils

  ○ Basophils
• TYPES OF GRANULOCYTES

  • Neutrophils
  • Eosinophils
  • Basophils
• TYPES OF AGRANULOCYTES

  • Lymphocytes
  • Monocytes
• TYPES OF LEUKOCYTES

  ● Granulocytes

  ○ Granules in their cytoplasm can be stained

  ○ Possess lobed nuclei

  ○ Include neutrophils, eosinophils, and basophils
• TYPES OF LEUKOCYTES

  ● Agranulocytes

  ○ Lack visible cytoplasmic granules

  ○ Nuclei are spherical, oval, or kidney-shaped

  ○ Include lymphocytes and monocytes
• TYPES OF GRANULOCYTES

  Neutrophils

  • Multilobed nucleus (3-7 lobes connected by a thin strand of nucleoplasm); ”polymorphonuclear neutrophils”
  • Stains pale pink
  • Contains fine granules
• TYPES OF GRANULOCYTES Neutrophils

  • Function as phagocytes at active sites of infection; numbers increase during acute infection
  • 3,000 - 7,000 per mm3 of blood
  • 40-70% of WBCs
• TYPES OF GRANULOCYTES

  Eosinophils

  • Figure 8 or bilobed nucleus
  • Stains blue-red
  • Red coarse cytoplasmic granules
• TYPES OF GRANULOCYTES Eosinophils

  • Functions to kill parasitic worms by deluging them with digestive enzymes; plays a role in allergy attack
  • 100-400 per mm3 of blood
  • 1-4% of WBCs
• TYPES OF GRANULOCYTES

  Basophils

  • U or S-shaped nucleus
  • Stains dark blue
  • Large blue-purple granules (contains histamine)
• TYPES OF GRANULOCYTES Basophils

  • Release histamine at sites of inflammation; contains heparin (anticoagulant)
  • 20-50 per mm3 of blood
  • 0-1% of WBCs
• TYPES OF AGRANULOCYTES

  Lymphocytes

  • Large, dark purple nucleus
  • Slightly larger than RBCs
  • Reside in lymphatic tissues
  • Play a role in immune response
  • 1,500 - 3,00 lymphocytes per mm3 of blood
  • 20-45% of WBCs
• TYPES OF AGRANULOCYTES

  Monocytes

  • U or kidney-shaped nucleus
  • Largest of the WBCs
  • Function as macrophages when they migrate into tissues
  • Important in fighting chronic infection
  • 100-700 monocytes per mm3 of blood
  • 4-8% of WBCs