Biology 11 Chapter 12 Circulation

1. The transport system of the human body is known as? 2. The organ that pumps the blood to the whole body is? 3. The heart, trachea, esophagus and associated structures form a Middle portion known as? 4. The closed sac that surrounds the heart is known as? 5. The protective fluid between the membranes of the pericardium is known as?