the respiration in human start from breathing.the oxygen is inhale and passes through larynx and reaches upto trachea and it goes in the bronchus.it is also divided into bronchoioles. it leads into lung
the bronchoioles that enter in the lung lead to small air sac called alveoli and it exchange gases and here exchange of gas occur and carbon dioxide is transported back to nostril through same passage and the canbondioxie is exhaled.in this way the process of respiration is completed
hope this helped..
