| A | B |
|---|
| diffusion | the random distribution of particles throughout an environment |
| creation of blood cells | red bone marrow |
| iron-based molecule | hemoglobin |
| red blood cell | contains 250 hemoglobin molecules |
| platelets | clot-forming cells |
| homeostasis | maintenance of a stable internal environment |
| vasodilation | when a blood vessel's diameter increases |
| vasoconstriction | when a blood vessel's diameter decreases |
| pulmonary circuit | the path of blood from heart to lungs and back |
| systemic circuit | the path of blood around the body (except lungs) |
| blood vessel structure | tunica intima (endothelium); tunica media (smooth muscle); tunica externa (protective connective tissue) |
| capillary structure | 1 layer of simple squamous epithelium |
| veins | contain valves, thinner middle layer |
