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Health lesson 44
| Term | Definition |
|---|---|
| lymphocytes | white blood cells that help the body fight pathogens |
| B cell | a white blood cell that produces antibodies |
| anitbody | a special protein that helps fight infection |
| helper T cell | a white blood cell that signals B cells to produce antibodies |
| macrophage | a white blood cell that surrounds and destroys pathogens |
| immunity | the body's Resistance to disease-causing agents |
| active immunity | resistance to disease due to the presence of antibodies |
| vaccine | a substance containing dead or weakened pathogens that is introduced into the body to give immunity |
| passive immunity | immunity that results from introducing antibodies into a person's bloodstream |
| pathogen | a germ that causes disease |
| bacteria | single-celled microorganisms |
| toxins | poisonous substances |
| immune system | the system that removes harmful organisms from the blood and combats pathogens |
| Rickettsia | intracellular parasites that are classified as bacteria |
| fungi | a pathogen that includes single- or multi-celled parasitic organisms |
| virus | one of the smallest known pathogens |
| protozoa | tiny, single-celled organisms that produce toxins that cause disease |
| helminth | a parasitic worm |