The Cardiovascular System

5. Fine, narrow, microscopic blood vessels that allow gas and nutrients to be passed through the walls into tissues.
7. To complete one cycle, blood must pass through the heart this many times.
8. Thin blood vessels that carry blood back to the heart at low pressure.
10. circulation The body loop, where the left side of the heart transfers blood to the various parts of the body and back.
12. The relaxation phase of an atrium or ventricle.
15. A main artery that carries oxygenated blood from the heart.
16. fluid A liquid which lubricates the heart, allowing it to move freely without friction.
19. Harvey The name of the English doctor who in the 17th century discovered that the heart acts as a pump that pushes the blood out into the blood vessels for circulation.
20. The contraction phase of an atrium or ventricle.

1. A thick layer of muscle responsible for the heart's ability to contract and pump the blood.
2. The lower chamber of the heart.
3. The heart rate of an animal will generally be low and stay the same while it is at...
4. The name of the system responsible for circulating blood to the different areas of the body.
6. The heart rate will increase to be rapid during...
9. Thick, strong blood vessels that take blood away from the heart.
11. A hollow muscular organ that pumps blood through the circulatory system by rhythmic contraction and dilation.
13. The valve in the heart between the right atrium and the right ventricle.
14. The valve in the heart between the left atrium and left ventricle, also known as the mitral valve.
16. circulation The lung loop, where the right side of the heart transfers blood to the lungs and back.
17. The upper chamber of the heart.
18. vessels A network of tubes that provide transport for the blood to all areas of the body.
21. This divides the heart into left and right sections.