Chapter 4 Vocabulary

4. The force that blood exerts against the walls of blood vessels.
5. Cell fragments that help to form blood clots.
8. Small knobs of tissue that filter lymph, trapping bacteria.
9. A flap of tissue that prevents blood from flowing backward.
12. A hollow, muscular organ that acts as a pump for cardiovascular system.
13. A type of blood vessel that carries blood towards the heart.
17. One of two of the the upper chambers of the heart and receives blood coming into heart.
18. A group of cells in the right atrium that sends out signals to make the heart muscle contract.

1. Cells that take up oxygen in the lungs and deliver it to the body cells.
2. One of the two lower chambers of the heart, pumps blood out of the heart.
3. The largest artery in the body.
6. The body's drainage system with a network of veinlike vessels that returns the fluid to the bloodstream.
7. Cells that are the body's disease fighters.
10. A type blood vessel that carries blood away from the heart.
11. The smallest type of blood vessel that allows for exchange of materials between blood and body cells.
12. A protein containing iron that binds chemically to oxygen molecules.
14. The liquid part of the blood that carries some nutrients.
15. Fluid inside the lymphatic system consisting of water and dissolved materials.
16. Molecules move from an area of higher concentration to an area of lower concentration.