As parrot owners we’ve all heard that birds are very sensitive to smoke, kitchen fumes, and aerosols. However, I’m not sure how many of us really know why. It’s not just their small size that makes them susceptible to this stuff; birds’ lungs are set up very differently than ours.
Mammals have what is called “tidal breathing”. When we breathe in, we pull air into our lungs. It travels into the trachea (windpipe) and then successively forking bronchi. These end in structures called alveolar sacs, which are made up of a cluster of alveoli. Each alveolus (the singular of alveoli) is covered in blood vessels carrying deoxygenated blood.
Oxygen from the air we inhale diffuses over a membrane as long as there is more oxygen in the air than in the blood. Meanwhile, carbon dioxide is diffusing the other way. Then we exhale our deoxygenated air, rinse and repeat. There’s only so much we can exhale, so some air doesn’t make it out of our trachea. It works, but there’s a more efficient way to do it.
Mammals have what is called “tidal breathing”. When we breathe in, we pull air into our lungs. It travels into the trachea (windpipe) and then successively forking bronchi. These end in structures called alveolar sacs, which are made up of a cluster of alveoli. Each alveolus (the singular of alveoli) is covered in blood vessels carrying deoxygenated blood.
Oxygen from the air we inhale diffuses over a membrane as long as there is more oxygen in the air than in the blood. Meanwhile, carbon dioxide is diffusing the other way. Then we exhale our deoxygenated air, rinse and repeat. There’s only so much we can exhale, so some air doesn’t make it out of our trachea. It works, but there’s a more efficient way to do it.