The heart is a four chambered muscular pump located inside the chest .It is ‘heart’ of circulatory system. The heart is conical in shape. The heart is a mesodermal derivative. The adult human heart is roughly about the size of a closed fist. It is a myogenic heart. The heart is covered by a fibrous sac called pericardium. The wall of the heart is primarily made up of cardiac muscles called myocardium. The inner surface of the heart is lined with a thin layer of epithelial cells called endothelium. The heart is formed of four chambers, namely two auricles and two ventricles. The auricles are named as right and left auricles. The ventricles are named as right and left ventricles. The right and left auricles are separated by a fibrous partition called interatrial septum. Similarly, the two ventricles are separated by an interventricular septum. The auricles are separated from the ventricles by an auriculoventricular septum.
The right auricle opens into the right ventricle by a right auriculo ventricular aperture. Similarly, the left auricle opens into the left ventricle by a left auriculo ventricular aperture. The right auricle receives deoxygenated blood through three veins, namely inferior vena cava, superior vena cava and coronary vein. The left auricle receives oxygenated blood from the lungs through pulmonary veins. Two main blood vessels carry blood from the ventricles. One large aortic arch carries blood from the left ventricle to the various parts of the body except the lungs. The pulmonary aorta carries blood from the right ventricle to the lungs. The heart contains three types of valves. They are bicuspid valves , tricuspid valves and semilunar valves. The left auriculoventricular aperture is guarded by a valve called bicuspid valve . It has two flaps and hence the name ‘bicuspid’. The right auriculoventricular aperture is guarded by a tricuspid valve containing three flaps. Both bicuspid and tricuspid valves are fastened to small conical muscles called the papillary muscles on the ventricular wall through several tendinous strands, the chordae tendinae.