1) The ______ brings blood back to right atrium of heart from upper body. The ______ brings blood back to right atrium from lower body. The ______ brings blood from right ventricle to ______. The ______ brings blood from ______ to the left atrium. Circulation of blood from right ventricle through the lungs and back to the ______ is known as the ______ circulation. The ______ serves the rest of the body. The ______ brings blood away from left ventricle; it is as large as a garden hose. The ______ valve, also known as the ______ valve, prevents backflow of blood from left ventricle into left atrium. The ______ avoids backflow of blood from right ventricle into right atrium. The ______ valve avoids backflow of blood from aorta into left ventricle. The ______ valve avoids backflow of blood from pulmonary artery into the ______.

2) Key parts of cardiac circulation that offers blood to wall of the ______, are the ______, the ______, the ______ and the ______. Lack of blood to the heart wall can result in ______ or in ______.

3) The heart beat is regulated by the ______ of the heart. The ______ node, also known as the pacemaker of the heart, begins nerve impulse which spreads through heart. This starts the contraction of atria. The ______ delays the impulse a short time, enabling the time for the blood to fill the ______. Then message rapidly travels down septum of the heart in the ______. When message travels through ______, the ventricle walls contract.