LEUKOCYTES (White Blood Cells)

Classes 2 main classes: Granulocytes – have a grainy cytoplasm Agranulocytes – have a clear cytoplasm

Types There are 5 types of white blood cells: Granulocytes Neutrophils 40-75% Eosinophils 5% Basophils0.5% Agranulocytes Lymphocytes20-50% Monocytes1-5% The range is because the requirement for different types of WBCs vary from time to time.

Neutrophils Structure: Multilobed nucleus Inconspicuous granules Amount: 3-7,000/mm³ Functions: Engulfing bacteria & viruses (phagocytosis) Life Span: hours → days

Eosinophils Structure: Bilobed nucleus Large, red granules Amount: /mm³ Functions: phagocytosis Protects against parasitic infections Neutralize histamines (their amts. incr. during hay fever & allergy attacks) Life Span – hours → days

Basophils Structure: Lobed nucleus Large granules, but fewer Amount: 20-50/mm³ Functions: Become mast cells when they leave b.v. & produce histamines Respond to allergens rapidly (anaphylactic shock) Produce heparin (anticoagulant) Life Span – hours → days

Monocytes Structure: Largest WBC U-shaped nucleus Grayish blue cytoplasm Amount: /mm³ Functions: Phagocytosis Become macrophages & remove dead cells Life Span – weeks → months

Lymphocytes Structure: Most numerous in children; 2 nd most in adults Spherical nucleus Small “ring”of cytoplasm; pale blue Amount: /mm³ Functions: T cells – attack foreign antigens directly B cells – produce antibodies for immunity Life Span – months → lifetime

White Blood Cell Count Normal adult has 5,000-10,000 cells/mm 3 Leukocytosis- WBC count above 10,000 cells/mm 3 –Can be a sign of acute infection –Occurs during times of stress and vigorous exercise. Leukopenia- WBC below above 10,000 cells/mm 3 –Can be a sign of virus such as influenza, measles, mumps and HIV