Across
- 4. they have thick, muscular walls which pump blood through the arteries
- 6. white blood cells which attack pathogens by producing antibodies
- 7. the substance that bathes the cells in the body
- 11. ventricles contract from the bottom of the heart
- 13. blood vessel with valves that transports blood to the heart
- 15. changes in the oxygen dissociation curve as a result of carbon dioxide levels
- 16. the process of recognising and engulfing a pathogen
- 17. tiny blood vessels with walls one-cell thick where exchange of materials occurs
Down
- 1. atria and ventricles contract and relax in an irregular manner
- 2. blood passes through the heart twice
- 3. conducts the excitation down the septum of the heart
- 5. carbon dioxide + haemoglobin
- 8. contracts and relaxes without receiving signals from the nervous system
- 9. often leave the blood by squeezing through capillary walls
- 10. a protein found in the red blood cells
- 12. blood vessels that carry blood away from the heart
- 14. transports carbon dioxide, digested food, urea, hormones and heat