IMMUNE SYSTEM

The ABC's about your immune system...
Pathogens (Germs): an infectious agent

            Examples: virus, bacteria, fungus, prion

Macrophage: Type of white blood cell that attacks foreign invaders in the body; help destroy bacteria, tumors, etc. via phagocytosis

Antigen: Any foreign substance that can enter the body

Helper T cell: Type of white blood cell that recognizes antigens releasing cytokines that active B+ killer T cells

B cell: Lymphocytes that will release antibodies to fight off antigens; important role in immune system responses

Antibody: Proteins that bind to an antigen and neutralize it

Killer cell: Destroy antigens that are discovered by antibodies

Cytoxic T cell: Type of T-cell which kills cells that are infected with viruses and other pathogens

Memory cell: Immune cells with a long lifespan which remembers attacks by certain antigens; when those antigens return, memory cells trigger a quick immune response before the body experiences the symptoms  

Innate vs. adaptive vs. passive immunity
Innate immunity is a type of general protection which everyone is born with. It includes the external barriers of the body such as the skin and mucous membranes (lining of the nose, throat, gastrointestinal tract, etc.). These are the first lines of defense in preventing antigens from entering the body. It this is broken, the membranes attempt to heal quickly and specialize immune cells attack invading germs. The next type of protection is adaptive or active immunity. This develops throughout our life and involves the lymphocytes. As we are exposed to diseases or immunized against diseases through vaccination, adaptive immunity develops. Finally passive immunity is the last type of protection. It is a borrowed immunity from another source and only lasts for a short time

Immune Disorders

DiGeorge syndrome (thymic dysplasia): a birth defect and a primary T-lymphocyte disease in which children are born without a thymus gland (where T lymphocytes mature)

Chediak-Higashi syndrome (chronic granulomatous disease): the inability of the neutrophils (a type of white blood cells) to function normally as phagocytes (cells that digest foreign organisms)