Biology

2. Sacs in the lungs where oxygen diffuses into the blood and carbon dioxide diffuses into the air
4. Protein in the blood. Plasma produced in reaction to antigens that react with and disable antigens
6. Removes wastes and regulates blood pH levels.
7. Two lower chambers of the heart
10. Tube through which urine is passed from the urinary bladder to the outside of the body
11. Large, thick-walled muscular vessels that carry oxygenated blood away from the heart
12. One of the two sections of the heart that take in blood from the veins
13. Foreign substances that stimulates an immune response in the body
16. Recognizes diseases
21. Small cell fragments in the blood that help blood clot after an injury
22. Largest blood vessel in the body: transports oxygen-rich blood from the left ventricle of the heart to the arteries
24. Liquid composed of wastes that is filtered from the blood by the kidneys, stored in the urinary bladder and eliminated through the urethra

1. Microscopic blood vessels with walls only one cell thick
3. A membranous sac in many vertebrates that serves for the temporary retention of urine and discharges by the urethra
5. Individual filtering unit of the kidneys
8. Iron-containing protein molecule in red blood cells that bind to oxygen and carries it from the lungs to the bodys cells
9. Tube that transports urine from each kidney to the urinary bladder
14. Carries oxygen to all of the body's cells.
15. Force that blood exerts on blood vessels; rises and falls as the heart contracts and relaxes
17. Tubelike passageway for air flow that connects with two bronchi tubes that lead into the lungs
18. Surge of blood through an artery that can be felt on the surface of the body
19. Fluid portion of the blood. 55%
20. Any of the large veins by which in air-breathing vertebrates the blood is returned to the right atrium of the heart
23. Large blood vessels that carry from the tissues back toward the heart