1. How many main blood vessels are there?
2. If you have o positive type of blood who can give it to?
3. Which one is a disease that is when your heart beats slower?
4. What are the main two blood cells?
5. Which blood vessel has thin layers?
6. What do kidneys do?
7. How big is your heart?
8. Which blood vessel mostly is in your body?
9. How many main blood cells are there?