The term lacquer is used for a number of hard and potentially shiny finishes applied to materials such as wood. These fall into a number of very different groups.
Cardiac Muscle Tissue. Cardiac muscle tissue is an extremely specialized form of muscle tissue that has evolved to pump blood throughout the body. In fact, cardiac muscle is only found in the heart and makes up the bulk of the heartâs mass. The heart beats powerfully and continuously throughout an entire lifetime without any rest, so cardiac muscle has evolved to have incredibly high contractile strength and endurance.
The heart wall is composed of three layers. The middle layer, the myocardium, is responsible for the heartâs pumping action. Cardiac muscle, found only in the myocardium, contracts in response to signals from the cardiac conduction system to make the heart beat. Cardiac muscle is made from cells called cardiocytes. Like skeletal muscle cells cardiocytes have a striated appearance, but their overall structure is shorter and thicker.