The air we breathe goes through the nose, nasal passage and then through trachea or windpipe which separates into two branches called bronchial tube or bronchi one entering each lung the bronchi subdivide many times inside the lungs, analogous to the breathing pattern of grapes finally becoming hairlike tubes called bronchioles in the last part of the terminal bronchioles are tiny bubble like bunch of structure called alveoli or air sacs. :)