oxygen together with other gaseous materials enters the body through the nose where air is filtered by the cilia(hairs in the nostrils) of the nose to remove impurities with the help of mucous membrane that also traps tiny slit particles, it then enters the trachea then to the bronchi then bronchioles that leads to the air sacs or the alveoli, within the alveoli exchange of gases will take place between alveoli and the capillaries that surrounds it, the capillaries will give off carbon dioxide in exchange of oxygen, so blood in the capillaries will become high in oxygen content, the blood will go out from the lungs through pulmonary veins to enter the left side of the heart to be pumped out to different parts of the body to distribute oxygen.
