immune system

• Pathogen is a disease-causing organism
• Infectious diseases are caused by pathogens
• Nonspecific defenses are barriers that do not distinguish one invader from another
• Inflammatory response is a nonspecific defense characterized by redness, heat, swelling, and pain
• Histamines cause nearby blood vessels to dilate (expand)
• Interferon is a protein produced by cells in response to becoming infected by a virus
• Immunity means your body is resistant to the pathogen that causes a specific disease
• Antigen is a large molecule, usually a protein, that provokes an immune response
• Antibodies are proteins found on the surface of certain white blood cells, or in blood plasma, that attach to particular antigens
• B cells are lymphocytes that continue development in bone marrow (humoral immunity)
• T cells are T lymphocytes that are transported to the thymus gland where they mature (cell-mediated immunity)
• Humoral immunity originates from B cells
• Cell-mediated immunity originates from T cells
• Memory cells lay dormant and remember the pathogens that they previously attacked
• Cytotoxic T cells attack cells infected with the pathogen that triggered the response. They are also known as assassin cells
• Active immunity is when your body produces antibodies against infection
• Passive immunity is when your body receives antibodies for a particular disease from another source
• Allergy is an abnormal over-sensitivity to an otherwise non-harmful antigen, called an allergen
• Autoimmune disease is when the immune system turns against some of the body's own molecules
• AIDS stands for Acquired Immune Deficiency Syndrome