| A | B |
|---|
| infectious disease | communicable disease; caused by organisms or viruses that enter and multiply within the human body |
| microorganism | organism that are so small that they can be seen only through a microscope |
| pathogen | microorganisms and viruses that cause disease |
| bacteria | simple, single-celled microorganisms |
| toxin | poison given off by some bacteria; injures cells |
| virus | the smallest pathogens; can multiply only after entering a living cell; takes over cell's reproductive mechanisms, resulting in damage or death |
| fungi | organisms such as yeasts, molds, and mushrooms |
| protozoan | single-celled organisms that are much larger and more complex than bacteria |
| mucous membrane | protective linings that secrete a liquid to trap and attack pathogens |
| inflammation | your body's general response to all kinds of injury |
| phagocyte | white blood cells that engulf and destroy pathogens |
| immune system | fight disease by producing a separate set of weapons for each kind of pathogen it encounters |
| lymphocyte | white blood cells that carry out most of the immune system's functions |
| immunity | the body's ability to destroy pathogens that it has previously encountered before the pathogens are able to cause disease |
| T cell | lymphocytes; killer, helper, and suppressor; help immune system remember pathogens |
| B cell | lymphocytes that produce antibodies |
| antibody | protein that attaches to the surface of pathogens or to the toxin produced by the pathogens |
| lymphatic system | a network of vessels that collects fluid from your tissues and returns it to the bloodstream |
| immunization | injections to protect from some common infectious diseases; causes you to become immune to the disease |
| vaccine | substance injected in an immunization; contains small amounts of dead or modified pathogens or their toxins |
| antibiotic | a drug that inhibits or kills bacteria |
| epidemic | an unusually high occurrence of a disease in a certain place during a certain time period |
| emerging disease | an infectious disease that has become increasingly common in humans within the last 20 years or threatens to become more common in the near future |
