2. Defense Against Infectious Diseases

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

4. 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)

5. 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)

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

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