Simple structure of heart

Cardiac Muscle Definition Cardiac muscle, also known as heart muscle, is the layer of muscle tissue which lies between the endocardium and epicardium. These inner and outer layers of the heart, respectively, surround the cardiac muscle tissue and separate it from the blood and other organs. Cardiac muscle is made from sheets of cardiac muscle cells. These cells, unlike skeletal muscle cells, are typically unicellular and connect to one another through special intercalated discs. These specialized cell junction and the arrangement of muscle cells enables cardiac muscle to contract quickly and repeatedly, forcing blood throughout the body. Cardiac Muscle Structure Cardiac muscle exists only within the heart of animals. It is a specialized form of muscle evolved to continuously and repeatedly contract, providing circulation of blood throughout the body. The heart is a relatively simple organ. Through all the twists and turns and various chambers, there are only three layers. The outer layer, known as the epicardium or visceral pericardium, surround the cardiac muscle on the exterior. This helps protect it from contact with other organs. The parietal pericardium attaches to this outer layer creates a fluid-filled layer which helps lubricate the heart. The inner layer, or endocardium, separates the muscle from the blood it is pumping within the chambers of the heart. In between these two sheets lies the cardiac muscle. Cardiac muscle is sometimes referred to as myocardium. This...