Link to Specific Defense Mechanisms Diagram
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.
Major histocompatibility complex - MHC - "Self" proteins that can hold and present "foreign" antigens
**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.