Microbe - Sometimes referred to as a microorganism, a microbe is an organism that is microscopic and thus invisible to the naked eye. ⏎
Infectious Disease - A type of illness caused by a pathogenic agent, including viruses, bacteria, fungi, protozoa, parasites, or abnormal proteins known as prions.⏎
Immune System - The system of biological structures and processes that protects the body from foreign substances, including pathogens.⏎
Mucous Membrane - The moist linings of body passages and internal cavities involved with absorption and secretion of substances.⏎