Across
- 2. when you pull in oxygen
- 3. air sacs that can hold gases and can release it
- 5. a huge, flat part that brings oxygen in and out
- 6. a organ that is filled with oxygen when you breath
Down
- 1. a blood vessel that is really tiny
- 4. when take out air from your body
- 5. a movement from a low to a high concentration