The Lungs
The lungs and airways are like an upside-down tree.
The trunk of the tree is your large airway (trachea or windpipe) that divides into the left and right main airways (bronchi), which then branch off into smaller airways (bronchioles) until they get to the alveoli (air sacs).
The alveoli fill up with air when you breathe in to deliver oxygen to the blood stream and remove carbon dioxide.
