Cytokine - A type of protein secreted by cells in the immune system that carries signals that facilitate cell-to-cell communication and help regulate the way the immune system responds to inflammation and infection.⏎
Ecology - A branch of science that deals with the relation of organisms to one another and their physical environment.⏎
Exoskeleton - An external skeleton that protects and supports an organism, in contrast to an internal endoskeleton.⏎
Contagion - A general term for any disease-causing infectious agent spread by direct or indirect contact.⏎