Overview of the lungs
The lungs are part of the respiratory (breathing) system and are located in the chest, inside the rib cage and above the diaphragm. Lungs are complex organs that consist of spongy, elastic tissue that is designed to transfer oxygen from the air we breathe into our blood stream and remove carbon dioxide from out blood.
Oxygen in air enters the lungs when we take a breath. It is distributed throughout the lungs by a system called the bronchial tree. It is easiest to imagine the bronchial tree as an upside-down tree starting at our mouth and spreading out across the upper part of our chests. The first tube (airway) is called the trachea or wind pipe. This is similar to the trunk of a tree and guides the oxygen down through out neck. The trunch splits in two and becomes the left and right bronchus. As the branches spread out they become thinner until their width is less than 1 mm (bronchioles).
The bronchial tree carries air to small sacs (alveoli) deep within the lungs where oxygen moves from the lungs into the blood stream and carbon dioxide, a by product of our metabolism, moves from the blood into the lungs to be exhaled (blown out). The mechanics of breathing in oxygen and delivery to tissue in blood is necessary for all of the cells in our body to function. Removal of carbon dioxide is necessary to prevent the body becoming too acidic.
The air we breathe contains many dangerous particles from the environment such as dust, pollens, bacteria, viruses, smoke, and damaging chemicals. Our lungs maintain a system of defence against these potentially toxic invaders. This includes immune cells and secretion of mucus to trap and remove these unwanted substances from the lungs. Every time we cough up sputum we are also coughing up thousands of microscopic particles that could have damaged our lungs.