| A | B |
|---|
| infection | Invasion of the body by a microorganism |
| pathogen | An organism that causes disease |
| vector | An insect, rodent, or other organism that carries and transmits a pathogen from one host to another |
| lymphatic system | A system of vessels and organs that picks up excess fluid, proteins, lipids, and other substances from the tissues |
| systemic infection | An infection spread by the blood or lymphatic system to large portions of the body |
| neutrophil | A type of white blood cell that engulfs foreign organisms and infected, damaged, or aged cells |
| macrophage | A large phagocytic (cell-eating) cell that devours foreign particles |
| natural killer cell | A type of white blood cell that directly destroys virus-infected cells and cancer cells |
| lymphocytes | A white blood cell continuously made in lymphoid tissue as well as in bone marrow |
| T cell | A lymphocyte that arises in bone marrow and matures in the thymus (thus its name) |
| B cell | A lymphocyte that matures in the bone marrow and produces antibodies |
| helper T cell | A lymphocyte that helps activate other T cells and may help B cells produce antibodies |
| killer T cell | A lymphocyte that kills body cells that have been invaded by foreign organisms; also can kill cells that have turned cancerous |
| suppressor T cell | A lymphocyte that inhibits the growth of other lymphocytes |
| antibody | A specialized protein, produced by white blood cells, that can recognize and neutralize specific microbes |
| memory T and B cells | Lymphocytes generated during an initial infection-can later "remember" the specific antigens - destroy them |
| autoimmune disease | A disease in which the immune system attacks the person's own body |
| antigen | A marker on the surface of a foreign substance that immune system cells recognize as nonself and that triggers the immune response |
| histamine | A chemical responsible for the dilation and increased permeability of blood vessels in allergic reactions |
| cytokine | A chemical messenger produced by a variety of cell types that helps regulate many cell functions |
| immunity | Mechanisms that defend the body against infection; specific defenses against specific pathogens |
| acquired immunity | The body's ability to mobilize the cellular "memory" of an attack by a pathogen to throw off subsequent attacks |
| incubation | The period when bacteria or viruses are actively multiplying inside the body's cells; usually a period without symptoms of illness |
| prodromal period | The stage of an infection, following incubation, during which initial symptoms begin to appear but the host does not feel ill |
| vaccine | A preparation of killed or weakened microorganisms, inactivated toxins, or components of microorganisms- administered to stimulate an immune response |
| allergy | A disorder caused by the body's exaggerated response to foreign chemicals and proteins |
| allergen | A substance that triggers an allergic reaction |
| anaphylaxis | A severe systemic hypersensitive reaction to an allergen (difficulty breathing-low b.p.-heart arrhythmia-seizure-sometimes death) |
| bacterium (plural, bacteria) | A microscopic single-celled organism; about 100 bacterial species can cause disease in humans |
| pneumonia | Inflammation of the lungs, typically caused by infection or exposure to chemical toxins or irritants |
| mycoplasma | A small bacterium with an incomplete cell wall that may cause sore throats, ear infections, and pneumonia |
| meningitis | Infection of the membranes covering the brain and spinal cord (meninges) |
| streptococcus | Any of a genus (Streptococcus) of spherical bacteria |
| staphylococcus | Any of a genus (Staphylococcus) of spherical, clustered bacteria commonly found on the skin or in the nasal passages |
| toxic shock syndrome (TSS) | Sudden onset of fever, aches, vomiting, and peeling rash, followed in some cases by shock and inflammation of multiple organs |
| tuberculosis (TB) | A chronic bacterial infection that usually affects the lungs |
| endemic | Persistent and relatively widespread in a given population |
| rickettsia | A bacterium that can reproduce only inside living cells, transmitted by ticks, fleas, and lice; causes Rocky Mtn. spotted fever and typhus |
| virus | A very small infectious agent composed of nucleic acid (DNA or RNA) surrounded by a protein coat |
| parasite | An organism that lives on or within a living host; the relationship benefits the parasite and harms the host |
| contagious disease | A disease that can be transmitted from one person to another; most are viral diseases, such as the common cold and flu |
| influenza | Infection of the respiratory tract which is highly infectious and adaptable |
| epidemic | The occurrence in a particular community or region of more than the expected number of cases of a particular disease |
| pandemic | A disease epidemic that is unusually severe or widespread |
| herpesvirus | A family of viruses, responsible for cold sores, mononucleosis, chicken pox, and the STD known as herpes |
| encephalitis | Inflammation of the brain |
| hepatitis | Inflammation of the liver, which can be caused by infection, drugs, or toxins |
| jaundice | Increased bile pigment levels in the blood, characterized by yellowing of the skin and the whites of the eyes |
| poliomyelitis | A disease of the nervous system, sometimes crippling; vaccines now prevent most cases of polio |
| fungus | A single-celled or multicelled organism that absorbs food from living or dead organic matter |
| protozoan | A microscopic single-celled organism that often produces recurrent, cyclical attacks of disease |
| malaria | A severe, recurrent, mosquito-borne infection caused by the Plasmodium protozoan |
| giardiasis | An intestinal disease caused by the protozoan Giardia lamblia |
| parasitic worm | A pathogen that causes intestinal and other infections; includes tapeworms, hookworms, pinworms, and flukes |
| prion | Proteinaceous infectious particles thought to be responsible for a class of neurodegenerative diseases |
| toxin | A poisonous substance produced by a microorganism |
