1. During the atrial systole, the atrial muscles _______.   contract   relax   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. During the ventricular systole, the semilunar valves are closed.   True   False   5. The left auricle of the heart receives _______ blood from the lungs.   deoxygenated   oxygenated   6. Which fluid fills up the space between all human body cells?   intracellular fluid   extracellular fluid   extercellular fluid   intercellular fluid   Hint Half-n-half Clue   7. The _______ of the heart pumps the blood up to the lungs only.   right auricle   right ventricle   left ventricle   left auricle   Half-n-half Clue