Across
- 5. Give substances to cells and take away waste.
- 7. donor Another name for blood type O.
- 15. Skin, hair, nails and some glands.
- 17. gland Structure of the skin that helps to regulate temperature.
- 18. The second level of organization of the human body.
- 20. The involuntary muscles surrounding hollow organs.
- 22. The voluntary muscles of the body.
Down
- 1. Carry blood away from the heart.
- 2. The third level of organization of the human body.
- 3. The shoulders, arms, hands, hips, legs, and feet.
- 4. valve The "door" that leads to the lungs.
- 6. The involuntary muscle of the heart.
- 8. Structure of the skin that allows us to feel things.
- 9. The skull, vertebrate column, ribs, and sternum.
- 10. Form blood clots to repair a hurt blood vessel.
- 11. Group of organs working together.
- 12. The most inner layer of the skin; contains fatty tissue.
- 13. The blood flows from the right ventricle to the ...
- 14. valve The "door" that leads to the aorta.
- 16. atrium The heart chamber in which the blood arrives from the body.
- 19. Produces red blood cells, white blood cells, and platelets.
- 21. Carry blood back to the heart.