1. Plasma is a constituent of blood.   True   False   2. During the ventricular systole, the blood enters the ventricles.   True   False   3. When the auricles of the heart contract, the ventricles relax, and vice versa.   True   False   4. The inferior vena cava carries blood from the upper parts of the body to the heart.   True   False   5. During the atrial systole, the openings of the pulmonary vein and the vena cava are _______.   closed   open   6. During the ventricular systole, the semilunar valves are closed.   True   False   7. The cardiac veins carry blood to the walls of the heart.   True   False