The Body Regions
- Innate immunity: (Non-specific immunity)
- 1st line of defense:
- Physical barriers: (skin, mucous membrane) prevent entry of pathogens
- Chemical barriers: (antimicrobial proteins, saliva, tears, stomach acid) kill pathogens
- 2nd line of defense:
- Inflammation: Swelling, redness, fever, pain
- Phagocytosis: Engulfing/digesting microbes AND apoptosis cells
- Natural killer cells: induce apoptosis in infected OR cancerous cells
- Adaptive immunity: (Specific immunity)
- 3rd line of defense that responds to antigens
- Antigens: Foreign molecules recognized by the body
- Lymphocytes: White blood cells (B cells and T cells)
- B cells: produce antibodies that bind to antigens and mark them for destruction
- T cells: Helper T cells activate B cells and cytotoxic T cells (killer T cells) directly kill infected cells
- Immunological memory: ability to remember past infections and mount a swifter response upon re-exposure
- Vaccines
- Contain weakened/inactive pathogens to stimulate immunity
- Herd Immunity: Protects unvaccinated individuals by reducing the spread of diseases