Immune System

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Link to Immune System Diagram  Look !

Link to Specific Defense Mechanisms Diagram  Look !

Pathogen - Viruses, bacteria, fungi and other microorganisms. Any substance capable of stimulating an immune response.

          Antigen - Proteins on the cell surface that the immune system recognizes as "self" and any other antigens it encounters must be foreign.

*Nonspecific defense mechanisms - Work against any pathogen. They keep pathogens from getting into the body or destroy them if they do get in.

          Skin, Mucus and Cilia in Respiratory Tract - Act as a barrier to keep out pathogens. Skin has antibacterial enzymes.

          Stomach Acid and Acid in the Vagina - Dissolve pathogens.

          Tears and Sneezing - Push pathogens away from the body.

          Macrophages - Are WBC's and they phagocytize foreign invaders.

          Neutrophils - Are most numerous WBC's and they phagocytize foreign invaders.

                    Phagocytize - Phagocytic cell - Surround/envelop and digest/destroy.

          Inflammation - Causes localized swelling, redness, heat, and pain.

                    Mast Cells Release Histamine - Initiates the inflammatory response. This expands the blood vessels and brings more blood/WBC's to the site.

          Fever - A whole body inflammation. Slows down bacterial reproduction and speeds body repair. WBC's and antibodies work better at higher temps.

*Specific defense mechanisms - Are targeted at one specific pathogen.

Lymphocytes - WBC's - T lymphocytes (T cells) attack infected cells and B lymphocytes (B cells) make antibodies

          Macrophages - WBC's that can help with a specific pathogen.

                    "Antigen presenting cell" - They ingest a pathogen then display the pathogens antigen on their cell surface.

**Cell-mediated immunity - Work against "foreign" substances inside your cells or against cancer cells.

          T lymphocytes - 3 types of T cells - Made in bone marrow and go to thymus to learn "self" then used for Cell-mediated immunity.

                    Cytotoxic T cell - Detects and destroys(punch holes in the cell membrane) infected body cells in your body.

                    Helper T cell - Coordinate the entire immune response. Helper T cells are necessary for both the antibody mediated and cell mediated immunity.

                    Memory T cells - Used to fight reinfection by that specific pathogen.

**Antibody-mediated immunity - Work against "foreign" substances outside of your cells.

          B lymphocytes - B cells - 2 Types of B cells. Made in the bone marrow and used for Antibody-mediated immunity.

                    Plasma B cells - Produce and release (2,000/second) specific antibodies that then flow through the blood and bind to antigens on a specific pathogen.

                              Antibodies - A "Y" shaped structure that tags a pathogen. Will only bind with the antigen that stimulated its production, it can only recognize 1 type of antigen.

                    Memory B cells - Used to fight reinfection by that specific pathogen.

Allergy - Inflamation against something that is not a true pathogen.

          Mast Cells release Histamine - Initiates an inflammatory response. Causes more mucus to be made, localized swelling, redness, heat, and pain.

Primary response - The first time you are exposed to an antigen you fight off disease and make memory T and B cells.

Secondary response - The next time the same pathogen invades the memory T cells turn into cytotoxic T cells and memory B cells turn into Plasma B Cells.

Active immunity - You develop immunity (have memory T and B cells) after you are exposed to an pathogen/antigen.

          Immunizations - Injections of either weakened or dead pathogens which still have their antigens so you make memmory T and B cells.

Passive immunity - You get antibodies from another individual. Placenta, breast milk, injections.

Acquired Immune Deficiency Syndrome - AIDS - Discovered in 1981 and still no cure.

          HIV-1 virus - Attacks and destroys helper T cells. This stops normal immune functions.

Return to Greg Sievert's GB 100 Syllabus
Last updated on 4 January 2018