Respiratory Tract - The part of the anatomy that has to do with the passage of air and includes the nose, larynx, trachea, and lungs.⏎
Peptic Ulcer - An open sore that develops on the inner lining of the stomach or upper small intestine.⏎
National Institute of Allergy and Infectious Diseases (NIAID) - Part of the U.S. Department of Health and Human Services and the National Institutes of Health, NIAID conducts and supports basic and applied research to better understand, treat, and ultimately prevent infectious, immunologic, and allergic diseases.⏎
Prion - A causative agent of infectious disease that is composed primarily of protein.⏎
Natural Selection - The process by which certain heritable traits that contribute to the survival and reproductive success of an organism become more widespread within a population over successive generations.⏎