1) The ______ brings blood back to right atrium of heart from the upper body. The ______ brings blood back to right atrium from lower body. The ______ brings blood from right ventricle to ______. The ______ brings blood from the ______ to left atrium. The 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, avoids backflow of blood from left ventricle into left atrium. The ______ avoids backflow of blood from right ventricle into right atrium. The ______ valve avoids the backflow of blood from aorta into left ventricle. The ______ valve avoids the backflow of blood from the pulmonary artery into the ______.

2) Key parts of cardiac circulation that offers blood to the 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 controlled by ______ of the heart. The ______ node, also known as the pacemaker of the heart, starts the nerve impulse which spreads through heart. This starts the contraction of the atria. The ______ delays impulse a short time, enabling the time for blood to fill ______. Then the message quickly travels down the septum of heart in ______. When message travels throughout the ______, the ventricle walls contract.