Priyanka Yagnik

you are right sir.... atmosphere around us does not only contain oxygen but many other gases like hydrogen, nitrogen, carbon dioxide, helium, etc..... it also contains many impurities like smoke, dust, pollen, water vapour, spores etc....they can irritate lungs and cause severe reactions. our nose( Nasal hairs and mucus) acts as first line of defense. Nasal hairs are about 70-100 micrometer in diameter. they can trap most impurities which are bigger than 10 micrometer in size. the particles which are smaller in size enters the lungs.here bronchial tubes try to block particles we breathe in. however if particles are even smaller they pass these defenses and enter lungs. lungs are made up of small sacs called alveoli. alveoli is the place from which oxygen enters blood vessels and carbon dioxide leaves blood and come into lungs. our blood contains a receptor for oxygen, called haemoglobin. oxygen attaches to haemoglobin and is carried into the body by blood. while other cases cant find any recptors and are exhaled out along with carbon dioxide. trapped particles if enters lungs then they are coughed out when they irritate lining of lungs. very mintute particles sometime escapes all defenses any cause health issues( air borne diseases).

you are right sir that around us contains many other things that gases(hydrogen, nitrogen, argon) like pollen, mold, spores, dust patricles, etc... we dont breathe in just oxygen, we breathe in all these things also. Here our body defense mechanism helps us. we breathe through our nose. Nose has hair and mucus which acts as first line of defense for particles. human hair is 70 micrometer to 100 micrometer in diameter. particles over 10 micrometer are trapped by nasal hair and mucus. those particles which escape enters lung along with all other gases. these particles causes health issues. but as for gases....gases enter lungs which contain thousands of sacs of alveoli. this is where oxygen passes through the lining of alveoli and enters the blood. blood contains oxygen carriers(receptors) called haemoglobin which can bind to oxygen and carry them into the body. which for other gases our body dont have receptors so they are exhaled out along with carbon dioxide through the alveoli and lungs... there are many other factors also involved but its pretty complex.. hope this basic information was useful to you.... :)