Â© 2013 WebMD, LLC. All rights reserved. The teeth are the hardest substances in the human body. Besides being essential for chewing, the teeth play an important role in speech. Parts of the teeth include: â¢ Enamel: The hardest, white outer part of the tooth. Enamel is mostly made of calcium phosphate, a rock-hard mineral. â¢ Dentin: A layer underlying the enamel.
While they are often used synonymously, the terms infectious disease and communicable disease do not have the same meaning. A communicable disease is an infectious disease that is easily spread from one human to another.
Infectious diseases are those diseases which are caused by infectious agents (which include microorganisms such as bacteria, fungi, protozoa and virus, as well as some multice â¦ llular animals such as worms) and hence they are the ones which can spread from one person to another.inda a no brainer...infectious diseases can spread to one another. (Pandemic, Epidemic, flu, cold) and a non infectious disease does not spread...(Sickle cell, cancer, etc.) â¦ An infectious disease can be spread from one person to another and is caused by a pathogen.