Circulatory System

2. receives blood as it returns from the body cells
5. connects arterioles with venules, smallest veins
7. 90 percent water, with many dissolved, or suspended, substances
10. located between the right atrium and the right ventricle, closes when right ventricle contracts, allowing blood to flow to the lungs and preventing blood from flowing back into right atrium
12. receives blood from the right atrium and pumps blood
13. blood vessels that carry blood back to the heart
15. phase of heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries
16. flows the the circulatory system
19. the transportation system of the body
21. white blood cells, formed in the bone marrow and lymph tissue
22. receives oxygenated blood from the lungs
23. the muscular middle layer
24. muscular wall that separates the heart into a right side and a left side
25. double-layered membrane

1. fragments or pieces of cells that lack nuclei and vary in shape and size
3. Closes when the left ventricle is contracting, allowing blood to flow into the aorta
4. red blood cells produced in the red bone marrow at the rate of about one million per minute
6. carry blood away from heart
8. the largest artery in the body
9. receives blood from the left atrium and pumps blood into aorta
11. carries oxygen and gives blood its characteristic
14. smooth layer of cells that lines the inside of the heart
17. phase of the heartbeat when the heart muscles relaxes and allows the chambers to fill with blood
18. located between the right ventricle and the pulmonary artery, a blood vessel that carries blood to the lungs.
20. abnormal heart rhythms and can be mild to life threating