The Human Heart
The Human Heart The Human Heart is one of the most important organs in the entire human body. The heart is a muscular organ that acts like a pump to continuously send blood through the body. The heart beats approximately about seventy-two times per minute of our lives. Without the heart’s pumping action, blood can’t circulate within the human body. The heart is enclosed in a double walled sac called the Pericardium. The pericardium has outer and inner coats. The outer coat is tough and thickened, loosely cloaks the heart, and is attached to the central part of the diaphragm and the back of the sternum (breastbone). The inner coat is double with one layer closely adherent to the heart while the other lines the inner surface of the outer coat with the intervening space being filled with fluid. There is a superficial part of the sac and is called the Fibrous Pericardium. It protects the heart and anchors its surrounding structures, and prevents overfilling of the heart with blood. The hearts outer wall of the human heart is composed of three layers. The first outer layer is called the epicardium, which may also be called visceral pericardium. The epicardium, the inner layer of the pericardium, a conical sac of fibrous tissue that surrounds the heart and the roots of the great blood vessels. The heart has a middle layer called the myocardium and is composed of the muscle which contracts. In the inner layer which is also called endocardium tends to keep in contact with the blood the heart pumps. It merges with the inner lining endothelium of blood vessels and covers heart valves. Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle's chamber walls are only about a half-inch