Across
- 3. the tube that carries air to the lungs in humans and other animals that breathe air; windpipe.
- 4. the red liquid containing oxygen and nutrients that pumps through the veins and arteries of humans and many other animals.
- 5. blood vessels that carry blood back to the heart.
- 8. main organs of the respiratory system. They bring oxygen to the body and get rid of carbon dioxide.
- 9. blood vessels that carry blood away from the heart.
- 10. a wall of muscle that separates the chest and abdomen in humans and certain animals.
- 11. the organ that pumps blood through the body of a person or animal.
Down
- 1. a gas that is expelled from the body by the respiratory system.
- 2. a tiny blood vessel where substances are exchanged between the blood and the body cells.
- 6. a group of parts that work together as a whole.
- 7. the regular beating of the arteries that is caused by the beating of the heart.