1. Chapter 24 ~ The Immune System

2. Animal immune system

3. Phagocytic and Natural Killer Cells Neutrophils 60-70% WBCs; engulf and destroy microbes at infected tissue Macrophages enzymatically destroy microbes Natural killer (NK) cells destroy virus-infected body cells & abnormal cells

4. The Inflammatory Response Histamine triggers dilation and permeability of capallarie Chemokines: attract phagocytes Leukocyte-released molecules increase body temperature

5. The lymphatic system Involved in innate and acquired immunity. Functions are to return fluid from the interstitial spaces to the circulatory system, and to combat infection

6. Acquired Immunity Antigen: a foreign molecule that elicits a response by lymphocytes (virus, bacteria, fungus, protozoa, parasitic worms) Antibodies: antigen-binding immunoglobulin, produced by B cells. Vaccine : introduction of a harmless variant to stimulate immune system. Active immunity: immune system produces antibodies. Passive immunity: receiving pre-made antibodies.

7. Lymphocyte’s dual defense Types of lymphocytes: B cells develop in bone marrow, T cells develop in the thymus. Humoral immune response is the production of antibodies by B cells. Defend against bacteria and viruses found in body fluids. Cell mediated immune response is the production of defensive cells by T cells- phagocytes.

9. Clonal selection Clonal selection: antigen-driven cloning of lymphocytes Effector cells: short-lived cells that combat the antigen that secrete antibodies Memory cells: long-lived cells that bear receptors for the antigen

11. Immune Responses Primary immune response: lymphocyte proliferation and differentiation the 1st time the body is exposed to an antigen Plasma cells: antibody-producing effector B-cells Secondary immune response: immune response if the individual is exposed to the same antigen at some later time ~ Immunological memory

12. Antibodies (Ig) Two functions of antibodies: recognize and bind to antigens, and then to neutralize that antigen. The antigen binding site is shape specific for antigen. Antibodies mark specific antigens for destruction.

14. Helper T’s role in humoral and cell mediated responses Helper T cells release proteins that activate both cytotoxic T cells and B cells

15. Cytotoxic T cells destroy infected body cells

16. Summary of acquired immunity Humoral immunity B cell activation Production of antibodies Defend against bacteria, toxins, and viruses free in the lymph and blood plasma Cell-mediated immunity T cell activation Binds to and/or lyses cells Defend against cells infected with bacteria, viruses, fungi, protozoa, and parasites; nonself interaction