1. Inner lining of the heart: Answer Endocardium 2. Muscle layer of the heart-middle layer: Answer Myocardium 3. Outer layer of the heart: Answer Epicardium 4. The heart is covered by a fibroserous sac called the: Answer Pericardium 5. Which ventricle is bigger: Answer left ventricle 6. Blood flow through the heart (KNOWTHE LASTTWO): Answer right atrium-tricuspid valve to right ventricle-pulmonic valve to lungs (oxygenated) to pulmonary veins to left atrium-mitral valve to left ventricle-aortic valve to system circulation 7. What is the purpose of the valves in the heart?: Answer keep blood flowing in one direction 8. The electrical impulse normally begins in: