Respiratory system is the network of organs and passages by which air is taken into the lungs and carbon dioxide and oxygen are exchanged within the body. Respiratory system Respiratory system is the network of organs and passages by which air is taken into the lungs and carbon dioxide and oxygen are exchanged within the body.
Air enters the respiratory system through the mouth and nose, where it is warmed and moistened.
Air breathed in through the nose is filtered by the coarse hairs that line the nostrils, which trap large dust particles. At the entry to the windpipe is a flap, the epiglottis, which closes to prevent choking when food is swallowed. At its base, the windpipe divides into two tubes or bronchi, and one bronchus enters each lung. Both windpipe and bronchi are stiffened by rings of cartilage. As in the nose, the windpipe and bronchi produce dust-trapping mucus and have cilia to move this mucus up to the mouth.