cardiovascular system crossword puzzle

2. a colorless cell that circulates in the blood and body fluids and is involved in counteracting foreign substances and disease.
7. any of the tubes forming part of the blood circulation system of the body, carrying in most cases oxygen-depleted blood toward the heart.
8. any of the fine branching blood vessels that form a network between the arterioles and venules.
9. comprises the middle and thickest layer of the heart wall.
11. a short artery transporting deoxygenated blood from the heart towards the lungs.
13. a hollow part or cavity in an organ.
15. any of the muscular-walled tubes forming part of the circulation system by which blood (mainly that which has been oxygenated) is conveyed from the heart to all parts of the body.

1. a large vein carrying deoxygenated blood into the heart.
3. a blood cell responsible for transporting oxygen from the lungs to the body's tissues and carbon dioxide back to lungs.
4. the thin, smooth membrane which lines the inside of the chambers of the heart and forms the surface of the valves.
5. blood vessels that carry oxygenated blood from the lungs back to the heart.
6. each of the two upper cavities of the heart from which blood is passed to the ventricles.
10. the membrane enclosing the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane.
12. small, colorless cell fragments in our blood that form clots and stop or prevent bleeding.
14. the main artery of the body, supplying oxygenated blood to the circulatory system.