The lungs are the main organs of our respiratory system. The lungs are located on either side of the heart in the upper part of our chest and are protected by the ribcage.
The lungs are enveloped in a membrane called the pleura, which allows the lungs to move smoothly as they fill up with and empty out air when we breathe.
The lungs are separated from each other by the mediastinum, an area that contains other important organs including:
- the heart and its vessels
- lymph nodes
The left lung has two lobes called the left upper lobe and left lower lobe. The left lung is smaller than the right lung because it shares space with the heart.
The right lung, which is shaped differently than the left lung, has three lobes called the right upper lobe, right middle lobe and right lower lobe.
As we breathe, our lungs fill with air that comes into our body from our nose and mouth. It travels down our throat through the voicebox and windpipe. The air then enters the lungs through the bronchi, which branches into the left and right lungs.
These main bronchi that lead into the lungs divide into smaller and smaller bronchi, eventually becoming so small that they are now called bronchioles. This pattern of increasingly smaller bronchial passages looks like an upside-down tree. That is why this part of the respiratory system is often called the bronchial tree.
At the end of every bronchiole there is a cluster of air sacs called alveoli, which are responsible for exchanging oxygen and carbon dioxide with the blood.