Disease
A condition, other than injury, that prevents the body from working as it should
Pathogen
An organism that invades the body, causing disease
Virus
A nonliving particle of protein and DNA that reproduces by invading the cell of a living organism
Bacterium
Any one of many single-celled organisms without a nucleus
Antibiotic
A medicine produced by microorganisms used to destroy pathogens in humans and domestic animals
Fungus
The kingdom of organisms that are mostly multicellular, have cell walls made of chitin, and are heterotrophic decomposers
Parasite
An organism that survives by living and feeding on other organisms
Immune System
The body's primary defense against disease-causing pathogens
Antigen
A foreign protein found on the outer surfaces of cells that triggers an immune response
Antibody
A Y-shaped proteins produced by white blood cells that bind to specific antigens on pathogens marking them for destruction by other white blood cells
Microbe
Any microscopic organism
Vaccine
A substance made of a dead or weakened pathogen that contains its antigens that trigger the production of antibodies
AIDS
A disease that results when the HIV virus attacks the human immune system
Allergy
An overreaction of the immune system to a harmless antigen
Histamine
Chemicals released by mast cells during an allergic reaction that causes redness, itchiness, and swelling
Antihistamine
A chemical that blocks histamines from being released during an allergic reaction
Host
The organism in parasite relationship that provides a home and/or food for the parents
Immunity
The body's ability to destroy pathogens before they cause disease