Immune System The body’s defense system

Three Level Approach to Problem Level I - Non-Specific Defense: Prevent entry Skin Mucous Membrane Secretions of skin and mucous membranes

Level 2 – Non-Specific Defense: Search/Destroy at point of attack foreign objects White blood cells Antimicrobial proteins Inflammatory response

 Damaged cells release chem. Signals:  histamines  protoglandins  Capillaries dilate  More permeability  Clotting elements (Platelets) appear  Clotting begin  Phagocytic leukocytes enter region  Attracted to chem. sig.  Leukocytes consume pathogens and cell debris by phagocytosis

Level 3 - Specific Defense: Complex system of interacting cells (immune pathway) Pathogen  Macrophage  T- Cell  B-Cell  Antibodies

Lymphatic system (Protection 3) Lymph nodes, spleen, tonsils, thymus gland, appendix Lymph node – contains lymphocytes (T-cells, B-cells) -Filters pathogens -Armpits,neck, intestines…. -get big when infection present Type of white blood cell that defends the body

Macrophages identify germs When a germ invades our bodies, macrophages gobble up the germ and display its surface shape, or antigen, for other immune cells to see.

Helper T cells direct the defense Helper T cells spot the foreign antigen on the macrophage and begin to multiply. They alert other white blood cells and direct the body's defense.

B cells make antibodies B cells start to make chemicals called antibodies. Antibodies lock onto foreign antigens making it easier for other immune cells to destroy them.

Killer T cells destroy germs Alerted by helper T cells, killer T cells multiply and destroy the invading germs. Working together, our white blood cells can usually destroy invading germs.

Antibody An antibody is a protein used by the immune system to identify and neutralize foreign objects like bacteria and viruses. Each antibody recognizes a specific antigen unique to its target.

Antibody Immunity Antigen – the foreign invader surface proteins (recognized phagocytes/lymphocytes) –When an antigen is present, body produces ___________ in response, that are specific (complementary) to that antigen (shape matches!) antibodies

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What? I don’t understand! Macrophage eats pathogen (puts antigen on surface) Proteins from antigen are expressed on macrophage surface T-cells recognize these antigen proteins as non-self and start signaling Some become Killer T-cells – secrete enzymes directly into infected cells and kill them Others become Helper T-cells which stimulates more Killer T-cell growth, and stimulates growth of B-cells and their production of antibodies (helper T-cells are like the conductor of an orchestra – telling everyone when and how to play)

Vaccines (Active immunity)– viral protein without genetic Info. (either from outside of envelope or the capsid protein itself) Prepares immune system for future Attacks, gives time to build up defense (helps Acquired Immunity)

Vaccines Inactivated bacteria or virus Provokes immune response but not the disease or illness Memory cells react faster to second exposure Some pathogens mutate too quickly to be eliminated by vaccines

Antibiotics Chemicals produced by other organisms (like other bacteria or fungi) that kill/inhibit bacterial growth (not viruses!) Eg. Penicillin, Ampicillin…. Harms/prevents formation of bacterial cell wall (makes holes) – causes water to flow in [from high to low concentration, remember?] and kills bacterium.