The human heart is located directly behind the middle and lower part of the sternum. The human heart is the size of a fist and weighs about 250 grams. The female heart is usually smaller and lighter than the male heart. The heart has a peach-like shape and is located mainly above the diaphragm, to the left between the lungs. The main function of the heart is to power the flow of blood to all parts of the body. The heart consists mainly of heart muscle, including the left ventricle, left atrium, right ventricle, right atrium four chambers, the left and right atrium and the left and right ventricles are separated by the septum, so they do not communicate with each other, the atria and the ventricles will also have valves between the atria and the ventricles, these valves so that the blood can only be from the atria into the ventricles, but can not be backward flow. The location of the heart is usually similar to the description of the heart fossa, the medical term is called the lower middle part of the sternum directly behind. If there is chronic emphysema disease, the left-sided portion may be compressed closer to the center by the lungs. The heart is a major organ of the circulatory system in higher animals and is also very important to the body and strict attention should be paid to the health of the heart organ.