Health & PE10 Human Movement (2015): Lungs

The cone-shaped lungs are sponge-like organs that fill the chest cavity and make up most of the lower respiratory tract. Their most important job is providing oxygen to capillaries so they can oxygenate blood.

Each lung is divided into lobes. The right lung has three, but the left lung has only two, thus allowing room to accommodate the heart.

Together, the lungs’ tissue surface is almost 40 times greater than the body’s outer surface, making the lungs (together) one of the largest organs in the body.

Each lung houses a bronchial tree, which gets its name from the intricate network of air passages that supply the lungs with air. The air-filled sacs in the lungs called alveoli resemble grape clusters. White blood cells known as macrophages, located inside each alveolus, ingest and destroy airborne irritants that enter the lungs. After you exhale, the lungs stay partly inflated because of a fluid called surfactant that is produced by special cells and secreted within the alveoli. Surfactant contains fatty proteins and helps to prevent lung infections.

he lungs exchange oxygen and carbon dioxide between the air we breathe and the blood

·       The tracheobronchial tree is the passageway from the mouth to the interior of the lung.

·       Gas exchange occurs in the alveoli deep in the lungs.

·       Breathing air in (inhalation) requires muscular effort.

·       Air is warmed, humidified, and cleaned by the nose and lungs.

What does breathing accomplish?

The cells in the body constantly need a new supply of oxygen to produce energy. With lack of oxygen, cellular function is impaired and damage or cell death may occur. As energy is utilised, waste products are created, one of which is the gas carbon dioxide. Eliminating carbon dioxide from the body is just as important as breathing in oxygen from the air. If carbon dioxide builds up in the blood it will lead to headaches, drowsiness, coma, and eventually even death.

What are the lungs?

The lungs are a pair of organs in the chest that are primarily responsible for the exchange of oxygen and carbon dioxide between the air we breathe and the blood.

What is the structure of the respiratory system?

Air enters the body via the nose (preferably) or the mouth. The air enters the main windpipe, called the trachea, and continues en route to each lung via either the right or left bronchus (plural=bronchi). The lungs are separated into sections called lobes, two on the left and three on the right. The air passages continue to divide into ever smaller tubes, which finally connect with tiny air sacs called alveoli. This gradually branching array of tubes is referred to as the tracheobronchial "tree" because of the remarkable similarity to the branching pattern of a tree.

The other half of the respiratory system involves blood circulation. Venous blood from the body is returned to the right side of the heart and then pumped out via the pulmonary artery. This artery splits in two for the left and right lungs and then continues to branch much like the tracheobronchial tree. These vessels branch into a fine network of very tiny tubes called capillaries. The capillaries are situated adjacent to the alveoli and are so small that only one red blood cell at a time can pass through their openings. It is during this passage that gases are exchanged between the blood and the air in the nearby alveoli. After passing the alveoli, capillaries then join together to begin forming the pulmonary veins, which carry the blood back to the left side of the heart.