The lung<span> is located in the thorax, where its delicate tissues are protected by the bony and muscular thoracic cage. The lung provides the organism with a continuous flow of oxygen and clears the blood of </span>carbon dioxide. Atmospheric<span> air </span><span>is pumped in and out regularly through a system of pipes, called conducting airways, which join the </span>gas-exchange<span> region with the outside of the body. The airways can be divided into upper and lower airway systems. The transition between the two systems is located where the pathways of the respiratory and digestive systems cross, just at the top of the </span>larynx<span>.
