Across
- 2. site for gas exchange
- 4. small one-cell thick blood vessels
- 6. caused by blood clot trapped in blood vessel leading to brain
- 7. these prevent back-flow of blood
Down
- 1. a disease in which alveoli breaks down
- 3. a thin flap that prevents food entering the trachea
- 5. the biggest artery and sends oxygenated blood from heart to the body