The most important function of the lungs is to extract oxygen from the environment and transfer it to the bloodstream.
Taking more than 6 million breaths per year, these integral parts of the human anatomy deserve our attention and respect.1
In this article, we will look at the form and function of the lungs; we will also learn about diseases that affect the lungs and how to maintain healthy lungs.
Fast facts on the lungs
Here are some key points about the lungs. More detail and supporting information is in the main article.
- The left and right lungs are different sizes
- The lungs fill the majority of the chest cavity
- Each person takes more than 6 million breaths per year
- At the most basic level, lungs work like a set of bellows
- Without the production of surfactant, the lungs would collapse
- The lungs also play a part in regulating the acidity of the body
- Smoking tobacco is the biggest cause of lung-related complaints
- Lung tumors make up 15% of all diagnosed cancers and 30% of all cancer deaths
- There are a number of simple ways to help keep your lungs healthy.
Structure of the lungs
The right lung is smaller than the left lung.
The lungs are located in the chest, beneath the rib cage on either side of the heart. They are roughly conical in shape with a rounded point at their apex and a flat base where they meet the diaphragm.
Despite being a pair, the lungs are not equal in size and shape.
The left lung has an indentation where the heart resides (the cardiac notch), and the right lung is shorter to make space for the liver below.
Overall, the left lung has a slightly smaller weight and capacity than the right.
The lungs are contained within two membranes – the pulmonary pleurae. The inner layer directly lines the lungs and the outer layer is attached to the inner wall of the rib cage.
The space between the two membranes is filled with pleural fluid.
Function of the lungs
The lungs’ primary role is to bring in air from the atmosphere and pass life-giving oxygen into the bloodstream; from here, it can be circulated to the rest of the body.
Lungs have no musculature of their own, and so the mechanics of breathing are reliant upon the muscles of the diaphragm (to which it is attached), the intercostal muscles (between the ribs) and the muscles of the abdomen and neck.
The diaphragm – a conical muscle that sits below the lungs – powers the majority of the work involved in breathing. As it contracts, it moves down, stretching the chest cavity and consequently increasing the lungs’ capacity. This increase in volume decreases the pressure inside and sucks in air through the nose or mouth.
As the diaphragm relaxes and returns to its resting position, the volume of the lungs decreases, causing a pressure increase that expels the air.
The lungs are like bellows: as they expand, air is sucked in and, as they compress, carbon dioxide waste is pushed back out.
When air enters the nose or mouth, it travels down the trachea and beyond until it reaches a section called the carina. At the carina, the tube splits into two, creating two bronchi that lead to the left and right lungs.
From there, the pipe-like bronchi further split into smaller and smaller bronchioles. This ever-decreasing pipework eventually terminates in the alveoli. It is within the alveoli that gas exchange occurs.
On the next page, we look at the role of alveoli and surfactants and some other functions that the lungs carry out.