| A | B |
|---|
| arteries | carry blood away from heart, more elastic, smaller diameter |
| arterioles | small arteries, branch into capillaries |
| capillaries | smallest and most numerous vessels; exchange of materials here |
| venules | small veins; branch from capillaries |
| veins | carry blood to heart, thinner, with valves, larger diameter |
| atrium | heart chamber that receives blood returned to heart by veins |
| ventricle | heart chamber that pumps blood into an artery; thicker than atria |
| diastole | relaxation phase of heart cycle |
| systole | contraction phase of heart cycle |
| pericardium | membranous sace that encloses the heart |
| myocardium | thick layer of cardiac muscle that composes the heart wall |
| pulmonary circuit | transport of blood to and from lungs |
| systemic circuit | transport of blood to and from the body except the lungs |
| epicardium | thin membrane that is firmly attached to the exterior surface of the myocardium; called visceral pericardium |
| endocardium | inner surface of heart; single layer of squamous epithelium |
| precapillary sphincters | control blood flow in capillaries |
