How You Breathe
In a single day, you will take close to 20,000 breaths of air. When you breathe in, air travels into your mouth or nose, down your trachea, or windpipe, to your lungs. You have two lungs—one on the right side of your body and one on the left. Beneath your lungs is a sheet of muscle called the diaphragm. When this muscle moves down, air moves into your lungs. When the diaphragm moves up, air leaves your lungs.
Inside each lung are millions of air sacs called alveoli. When you breathe in, fresh air enters the alveoli. This air contains a lot of oxygen. Oxygen passes through the thin walls of the alveoli into your body.
As the cells in your body use oxygen, they release a gas called carbon dioxide. Red blood cells return to your alveoli carrying carbon dioxide. You get rid of this carbon dioxide when you breathe out. Working together, the trachea, lungs, alveoli, and other body parts involved in breathing make up your respiratory system.
Scientists ask questions and then collect data. Then they examine the data to find answers. You can also collect and examine data to answer questions about your body.
For example, what is your breathing rate, or number of breaths you take in a minute? To find out, count the number of times you exhale, or breathe out, during one minute. This is your breathing rate. How does your breathing rate compare with the rates of other animals in the chart?
| Animal | Breathing Rate (breaths per minute) |
|---|---|
| Blue Whale | 4 |
| Cat | 26 |
| Chipmunk | 65 |
| Guinea Pig | 90 |
| Horse | 10 |
| Mouse | 135 |