Im just doing this Circulatory Crossword and I do not know some of these answers?

Question

first word 9 across. Second letter is a and their are 6 letters.

The question is, When exercising your heart will beat...

12 across. 7 letters, sixth letter is e.

Capillaries fit b.... cells and have very thin walls.

14 across, 6 letters, 5th letter is E

Stop blood going the wrong way.

8 down, first letter c, 11 letters.

System we are studying at the moment.

13 down, 5 letters, third letter is i.

Pipes that lead to the heart.

LOL, iam p**s boredd. xD

Answer 1

1. faster

2. between

3. valves

4. circulatory

5. veins

Answer 2

12A- between

14A-Valves

8D-Circulatory

13D-veins?

Answer 3

9A- Faster

12A- Between

14A- Valves

8D- Circulatory

13D- Veins

Answer 4

14 across is valves