Across
- 4. When we breathe in, the pressure inside the chest does this
- 5. Our heart and breathing rate does this when we exercise
- 6. This is produced in respiration in animals when there is no oxygen
- 10. When we breathe in, the intercostal muscles and diaphragm do this
- 13. The liquid in blood
- 15. In an experiment, we try to keep these variables constant
- 16. Small tubes inside our lungs
- 20. The variable that you change in an investigation
- 23. This is produced in respiration in plants and fungi when there is no oxygen
- 26. These vessels have thick muscle and elastic walls to be able to withstand high pressure
- 27. This sugar is a reactant in respiration
- 28. This system includes the lungs
- 29. This gas diffuses into the blood from the lungs
Down
- 1. Humans have this type of circulatory system – blood gets pumped to the lungs and then back to the heart before going to the body
- 2. These vessels have thin walls and valves
- 3. The variable that you measure in an investigation
- 7. This gas is found dissolved in blood plasma
- 8. The heart is a muscular _______
- 9. Respiration in the absence of oxygen
- 11. These tiny blood vessels surround the alveoli
- 12. Windpipe
- 14. The mechanical process which allows us to breathe
- 17. The shape of the alveoli give them a large ________________
- 18. A protein found in red blood cells
- 19. The shape of red blood cells
- 21. Capillaries are one cell thin to aid this process
- 22. This system includes the heart
- 24. Small air sacs where gas exchange takes place
- 25. Respiration in the presence of oxygen