B. prevent blood from moving too rapidly. C. prevent blood from moving in the wrong direction. D. stop the circulation whenever necessary. E. act as filters. C. pulmonary artery D. right atrium E. superior vena cava 22.
Blood returning to the heart from the lungs enters the A. left ventricle.
B. right ventricle. C. coronary artery. D. right atrium. E. left atrium. E. inferior vena cava 24.