Across
- 1. The muscular organ that pumps blood through the circulatory system
- 4. Tiny, disk-shaped cell that carries oxygen in the circulatory system
- 6. Tiny, thin-walled blood vessels where oxygen and nutrients are exchanged with tissues
- 7. Primary organ of the respiratory system
Down
- 2. The body's largest artery and a key part of the circulatory system
- 3. The main tube through which air enters the lungs
- 5. The gas essential for respiration