Circulatory system

3. – The middle muscular layer of arteries and veins.
4. – The main artery that carries oxygenated blood from the heart to the body.
6. – Rhythmic expansion of arteries as blood is forced through them.
9. – Iron-containing pigment in red blood cells that carries oxygen.
10. – The single layer of cells lining the tunica intima.
11. Blood vessel that carries blood away from the heart.
14. – The upper chambers of the heart that receive blood.
16. – The innermost layer of a blood vessel, in contact with the blood.
17. – Structure that prevents backflow of blood, found in veins and the heart.
18. – Describes how the heart can contract without external stimulation.

1. – The liquid portion of blood that carries dissolved substances.
2. – The chamber of the heart that pumps blood out through arteries.
5. – The outer connective tissue layer of a blood vessel.
7. – Vessel that carries blood towards the heart.
8. – The arteries that supply the heart muscle itself with oxygen.
12. – The smallest blood vessel, allowing exchange of substances with tissues.
13. VASORUM – Small blood vessels supplying the walls of large arteries and veins.
15. – The central cavity through which blood flows in a vessel.