ANATOMY

Detailed explanation-1: -Bacteria. These one-cell organisms are responsible for illnesses such as strep throat, urinary tract infections and tuberculosis. Viruses. Even smaller than bacteria, viruses cause a multitude of diseases ranging from the common cold to AIDS.

Detailed explanation-2: -Pathogens. A pathogen or infectious agent is a biological agent that causes disease or illness to its host. This term is most often used for agents that disrupt the normal physiology of animal or plant. Pathogens can be a bacterium, virus, or other microorganisms that can cause disease.

Detailed explanation-3: -Microorganisms that cause disease are collectively called pathogens. Pathogens cause disease either by disrupting the bodies normal processes and/or stimulating the immune system to produce a defensive response, resulting in high fever, inflammation? and other symptoms.