Across
- 2. The fluid that transports oxygen and nutrients throughout the body.
- 4. A gas that enters the blood in the lungs and is transported to body cells.
- 5. The smallest blood vessels, where substances are exchanged between the blood and body cells.
- 8. Blood vessels that carry blood back to the heart.
Down
- 1. The tiny air sacs in the lungs where oxygen enters the blood.
- 3. The muscular organ that pumps blood throughout the body.
- 6. Blood vessels that carry blood away from the heart.
- 7. The organs responsible for gas exchange in the respiratory system.