Lungs. Coloured computed tomography (CT) scan that displays a coronal slice through a human chest and its lungs (pink) seen from the front. The trachea (windpipe, black) runs down the image (from top centre) and brings air to the lungs from the mouth and nose (not seen). The trachea splits into two bronchi at upper centre. The bronchi then split further into smaller airways called bronchioles (not seen). CT scanning uses X-rays to construct slice images of the human body. A coronal slice is a vertical slice though the human body parallel to the line of the shoulders.