The cardiac system represents the heart and blood vessels. The blood is distributed to multiple organs present in the body. Capillaries are minute blood vessels, allow the gas exchange processes. Veins send blood to the heart from the capillaries. The heart is situated in the thorax, posterior to the sternum and superior surface of the diaphragm. The heart has four chambers, and two atria above and two ventricles below. The oxygenated blood moves to left portion of the heart and enters into the left atria and ventricle. The deoxygenated blood pumped into the right side of the heart and moves into the right ventricle and flows towards the lungs. The heart is covered with three protective layers which include an epicardium, myocardium, and endocardium. The cardiac physiological functions are controlled by a group of electrical impulses. The electrical impulse origin from the sinoatrial node and located on the top side of the right atrium. It causes atria muscle contractions and thereby sends blood into the ventricles. A cardiac cell demonstrated the electrical activity and transmits the cardiac impulses to the heart to maintain the normal heart beating and initiation of the cardiac cycle. The cardiac event causes the opening and closing of valves results in contraction and relaxation of cardiac chambers. The cardiac cycle consists of systole and diastole events, during the systole, ventricles contract and send blood to arteries and during diastole, the ventricle relaxes and collects blood from atria. The electrical activity of the heart originates from SA node and causes atria to initiate contraction of cardiac muscles and supply of blood into the ventricles.