ACROSS
2. River of life
4. The bridge between the brain and the rest of the body.
7. The basic structural unit of the nervous system.
9. The master organ of the body.
DOWN
1. Tiny air sacs.
3. Carry blood away from the heart.
5. Major organ of the respiratory system.
6. The pumping organ of the body.
8. Carry blood back to the heart.
