| A | B |
|---|
| Air sac | a structure in the lungs where blood picks up oxygen and releases carbon dioxide |
| Aorta | the largest artery that carries blood from the left ventricle to every part of the body, except the lungs |
| Artery | any blood vessel that carries blood away from the heart |
| Atrium | the upper chamber of the heart, which receives blood from the veins |
| Blood vessel | a tube that carries blood, such as an artery, a vein, or a capillary |
| Capillary | a tiny blood vessel that carries blood to and from the cells |
| Circulation | the movement of blood throughout the body |
| Heart valve | a flap in the heart that allows blood to flow only from the atrium to the ventricle |
| Vein | A blood vessel that carries blood back to the heart |
| Ventricle | the lower chamber of the heart, with strong muscles that pump blood to the body |
