The structure of the heart may it possible that the heart provides as a transport system pump which keeps blood continuously circulating through the blood vessels of the body.
Positioned within the thoracic cavity between the lungs, in the region known as the mediastinum, the heart is muscular, four-chambered, and hollow, and it is roughly the size of a clenched fist. It averages 310 grams in adult males and 255 grams in adult females. Directed downward to the left and rests on the diaphragm, the cone-shaped apex is roughly triangular. Directed toward the right is the base of the heart, which is the broad upper part where the large vessels attach. Therefore, tipping slightly to the left, the heart assumes an ablique position in the mediastinum.
A loose-fitting serous sac named the pericardium encloses and protects the heart. The heart is separated by the pericardium from the other thoracic organs. The pericardium forms the wall of the pericardial cavity, by which a watery pericardial fluid is included. An outer fibrous pericardium and an inner serous pericardium are actually composed by the pericardium. The lubricating pericardial fluid, which permits the heart to beat in kind of a frictionless bath, is formed by the serous pericardium.