Defense Against Infectious Diseases

•Prevent approach or entry of pathogens Nonspecific Defenses •Do not discriminate •Present at birth •Prevent approach or entry of pathogens

I. Physical Barriers Skin Creates effective barrier Hairs ( provide some protection against abrasion, keeps hazardous materials & insects from contacting skin Secretions (oil, sweat, & mucus): wash away pathogens & materials, contain chemicals that kill bacteria (lysozomes)

Specificity: Memory: Tolerance: Specific Defenses Targets specific cells with specific antigens Memory: Immune system remembers antigens it has encountered Tolerance: Immune system ignores normal (self) & attacks foreign (nonself)

I. Cellular Immunity Provides defense against abnormal cells & pathogens that are inside living cells Involves T cells Pg. 952

I. Humoral Immunity Provides defense against antigens & pathogens in body fluids Involves B cells