Lungs anatomy. Illustration of the macroscopic and microscopic anatomy of the human lungs, depicted on a classical statue. The trachea (windpipe) is shown descending to the lungs, with the lung at left shown with its normal, healthy (pink) appearance. The lung at right is shown in cutaway view to show the branching airways that divide (shown in insets) to terminate in sacs called alveoli. In the lungs, the process of gas exchange with the blood adds oxygen and removes carbon dioxide. The alveoli are enveloped by capillary blood vessels, some of which are shown here.