Air enters in to the nasal Cavity through the nostrils, Dust particles present in the air are prevented from entering the lungs. Air passes to the pharynx and then in to trachea, It has ‘C shaped rings which prevent it. From collapsing , Trachea is divided in to bronchi and in to bronchioles and a number of alveoli Blood circulating around the alveoli gives out CO2.
This oxygenated bolls reaches the cells and gives oxygen to the cells and is used for oxidizing glucose, co, formed as a product is carried by the blood to the alveoli and exhaled in the same path way.
