1. The cardiac veins carry blood to the walls of the heart.   True   False   2. During the atrial systole, the openings of the pulmonary vein and the vena cava are _______.   closed   open   3. Which fluid fills up the space between all human body cells?   intracellular fluid   extercellular fluid   intercellular fluid   extracellular fluid   Hint Half-n-half Clue   4. With reference to the heartbeat, the word 'systole' refers to a relaxation phase whereas the word 'diastole' refers to a contraction phase.   True   False   5. During the atrial systole, the atrial muscles _______.   relax   contract   6. Plasma is a constituent of blood.   True   False   7. The inferior vena cava carries blood from the upper parts of the body to the heart.   True   False