The respiratory system is the process responsible for the transport and exchange of gases into and out of the human body. When we breathe in, oxygen from the oxygen-containing air is drawn into the lungs through a series of air passages called the airways and into the lungs. As air is drawn into the lungs and waste gases are excreted, it passes through the airways, first through the mouth or nose, then through the pharynx, larynx, and windpipe, also called the windpipe . At this point, it then enters the lungs through the bronchi before finally reaching the air sacs called alveoli. In the lungs, through a process called diffusion, oxygen is transferred into the bloodstream through the alveoli (air tubes), where it is then transported inside red blood cells and carried to the body's organs. At the same time as oxygen is drawn into cells, waste products (carbon dioxide and water) are carried to the lungs where they are excreted when we exhale. When air is inhaled, it is humidified, warmed and cleansed. by tiny hairs called cilia in the respiratory system. These filter from...