1.  If oxygen rich air can not get into the lung and carbon dioxide rich air can not leave the lung, a perfectly healthy lung would still be absolutely useless.  To get fresh air into the lung, air first passes through the nasal passages or mouth, which leads to the trachea.

2.  The epiglottis serves as a protective flap of tissue that prevents food from entering the trachea.  If it were not for the epiglottis, food wood enter the trachea every time food is swallowed and cause the individual to choke.

3.  Separating the trachea from the upper aerodigestive track is the larynx.  The larynx is considered to function primarily as the voice box but also serves as an important regulator in respiration.

4.  The trachea, more commonly known as the windpipe, is the passage that leads from the throat to the lungs. 

5.  Extending from the trachea, the trachea divides into two large bronchiole tubes to service both lungs, then each bronchiole further divides within each lung to provide airflow throughout both lungs.

6.  Alveoli are very small air sacs at the ends of all the bronchioles that provide a surface for the exchange of oxygen and carbon dioxide.

7.  The pleura is a single membrane that folds over itself to form two membranes that separate the lungs from the chest wall.

8.  Oxygen rich blood returns to the heart from the lung through the pulmonary veins.

9.  Oxygen deficient blood gets pumped from the right ventricle to the lungs through the pulmonary arteries.

10.  The right lung is subdivided into 3 lobes that each have an extension of the bronchiole to provide oxygen from the air.

11.  The left lung is similar to the right lung, but only has 2 lobes instead of 3.