The human heart is at the back of the sternum and will be a little to the left. The apical beat of the heart can be clearly heard in the fifth intercostal space of the thoracic vertebrae. The heart is divided into four chambers: the left ventricle, the right ventricle, the left atrium, and the right atrium. They are separated by the atrioventricular valves, including the mitral and tricuspid valves. The heart is a vital organ of the human body, and if it stops beating, life will end. So usually must pay attention to protect the heart, less smoking and drinking, in order to prevent cause myocardial ischemia, atherosclerosis and other diseases. At the same time, avoid the indiscriminate use of drugs, in order to prevent accelerated aging of blood vessels and the heart.