The respiratory system, which consists of the nose, mouth, trachea, larynx, lungs and diaphragm, functions to supply oxygen to the entire body. Through the process of breathing, air that contains oxygen enters lungs. The lungs promote the exchange of oxygen and carbon dioxide, a waste product, with the blood. Many elements of the lungs play important roles in delivering life-giving oxygen to the body.
Muscles
In order to breathe, muscles around the lungs must contract. The diaphragm, a thin sheet of muscle that extends across the bottom of the rib cage, contracts and increases the space available in the chest cavity. The intercostals muscles found between the ribs also contract, increasing the chest cavity space further. The added space allows the lungs to expand, pulling in air through the mouth and nose.
Airways
The air sucked in through the mouth and nose travels through the trachea, the tube that enters the chest cavity. Once in the chest cavity, the trachea splits into two small tubes called bronchi. Each of these tubes divides further into more tubes known as the bronchial tubes. The bronchial tubes lead directly into the lungs, as described by the Franklin Institute, where they become smaller and smaller, directing the air to tiny air sacs.
Alveoli
The lungs contain over 600 million tiny spongy air sacs known as alveoli, according to the Franklin Institute. The alveoli function primarily to exchange the oxygen and carbon dioxide with the blood, making them vital to lung function. Because tiny capillaries surround the alveoli and the membrane between these air sacs and the capillaries is so thin, the exchange of oxygen and carbon dioxide occurs rapidly.
Cilia
The cilia are tiny hairs coated with mucus that function to protect the lungs from foreign particles. The airways, including the trachea, bronchi and bronchial tubes contain cilia. As air enters the airways, the cilia trap dirt, germs and any other particles and sweep them back up toward the nose and mouth, as described by the National Heart Lung and Blood Institute. The body then removes the foreign particles through coughing, swallowing or sneezing.
Pulmonary Artery
In order for the lungs to perform the gas exchange, they must be linked to the system of blood vessels. Arteries describe blood vessels that lead away from the heart. Although most arteries carry oxygen rich blood from the heart to the rest of the body, the pulmonary artery carries the carbon dioxide rich blood the veins delivered from the body to the heart into the system of capillaries that surround the alveoli.
Pulmonary Vein
Once the gas exchange is complete, the oxygen-rich blood then flows from the lungs back to the heart through the pulmonary vein. The heart then pumps the oxygen-rich blood to the rest of the body through the system of arteries.
