_______ are the small sacs that are the site of gas exchange in the lungs. In addition to being an airway, the _______ is the lo
cation of the human vocal cords. Cilia in cells along the trachea and nasal passages secrete _______ which traps dirt and particles from the air. Air is only approximately 21% oxygen. The majority of air is ______. The medulla oblongata controls the contraction and relaxation of the _______, causing the lungs to inflate and deflate during breathing. Explain the process of breathing. Begin with inhalation and describe the route that the air takes to the lungs, and what happens when the air reaches the lungs. Include in your description the terms: mouth, nose, pharynx, larynx, trachea, bronchi, lungs, alveoli, carbon dioxide, oxygen, and capillaries
10. Air enters the body through the mouth or nose and passes through the pharynx and larynx. Then it travels down the trachea and branches through the bronchi into the two lungs. In the lungs, small alveoli are the site of gas exchange where carbon dioxide diffuses into the lungs for exhalation, while oxygen from the air diffuses into the capillaries surrounding the alveoli to be pumped throughout the body.
