Across
- 2. Circulatory system where blood is confined within vessels.
- 7. Circulatory system where blood is not always confined to vessels.
- 9. Respiratory pigment found in many invertebrates.
- 10. Muscle that separates the thoracic cavity and aids in breathing.
- 12. Blood vessels that carry blood away from the heart.
- 13. Iron-containing molecule in red blood cells.
- 18. Blood cells involved in immune response.
- 19. Protein that helps in blood clotting.
- 20. Blood vessels that return blood to the heart.
Down
- 1. Protein in red blood cells that binds oxygen.
- 3. Type of circulation between the heart and lungs.
- 4. Process of moving air into and out of the lungs.
- 5. Fluid component of blood that carries cells and nutrients.
- 6. Smallest blood vessels where gas exchange occurs.
- 8. Blood cells responsible for oxygen transport.
- 9. Organ responsible for pumping blood throughout the body.
- 11. Blood vessels that carry blood to the lungs.
- 14. Primary organ for gas exchange in vertebrates.
- 15. Vessels that carry blood to the heart.
- 16. Process by which oxygen and carbon dioxide are exchanged.
- 17. Tiny air sacs in the lungs where gas exchange occurs.