Body passage is a term used to describe the pathways through which air and other substances travel in the body. The most common body passages are the iter, DUCT, and TRACHEA. The iter is a tube-like structure that connects the mouth and nose to the lungs. The DUCT is a tube-like structure that carries air from the lungs to the rest of the body. The TRACHEA is a tube-like structure that carries air from the nose and mouth to the lungs.