| Arterioles and venules are linked by tiny ____. |
amino acids |
| Inhaled asbestos and tobacco smoke are non-radioactive ____. |
atria (atriums) |
| The ____ are the two upper chambers of the heart. |
capillaries |
| Your two ____ take in oxygen and expel carbon dioxide. |
carcinogens |
| Proteins are polymers (chains) of ____. |
hormones |
| Insulin and glucagon are ____ that regulate blood glucose. |
lungs |
| Arteries, veins, and capillaries are blood ____. |
melanins |
| The various pigments that give skin and hair color are ____. |
vessels |
