The heart is a muscular hollow organ located inside the rib cage, between the lungs, behind the sternum. The heart is not perfectly centered, it mainly occupies the left side of our body.
In humans and other mammals the heart is divided into four chambers: upper left and right atria; and lower left and right ventricles.
The heart is wrapped in a seirous sac: the pericardium, which protects the heart from friction with other organs. The organ, itself, is made out of three layers: epicardium, myocardium, and endocardium.
The right atrium and the right ventriculus are connected by the atrioventricular tricuspid valve, while the left atrium and left ventriculus are connected by the atrioventricular mitral valve. Other valves are the semilunar valves (aortic and pulmonary), which permit blood to be forced into the arteries and prevent backflow from the arteries into the ventricles.
In this article, we are going to examine a pork heart, which is almost identical to a human one.