Air is a mixture of gas from which the body uses the oxygen. Respiratory system includes upper airways (nose, pharynx, larynx) and lower (trachea, bronchi, their ramifications and alveoli). The nose is, however, an organ that most people do not know much about. However it is extremely important in the act of breathing because the air inside it is heated and humidified. So his ability is amazing: it can heat the air in the nostrils to the tonsils up to 30 degrees Celsius. At this level, filtering of dust particles and retention of microbes takes place in the mucosa.