The Heart Muscle
The heart is a muscular organ and is made up of the four chambers and four valves. There are two upper chambers called the left and right atria and two lower chambers called the left and right ventricles. There are valves that are located between the chambers through which blood passes and the valves prevent the backward flow of blood.
The purpose of the pumping heart is to take deoxygenated blood through the veins and deliver to the lungs for oxygenation. The pumping action pumps the blood into the various arteries so that oxygen and nutrients can be supplied to the body tissues.
The heart is made primarily of cardiac muscle tissue that continuously contracts and relaxes so that it can pump the blood through the chambers and out into the blood vessels of the circulatory system. The actual heart muscle is composed of three layers, the epicardium which prevents excess expansion or movement of the heart, the myocardium which initiates contractions driving the cardiac cycle, and the endocardium that lines the cavities and valves.
The heart must also have a constant supply of oxygen and nutrients. This is supplied by the coronary arteries and there are two coronary arteries, referred to as the left and right coronary arteries that emerge from the beginning of the aorta, near the top of the heart. These coronary arteries branch off into smaller arteries so that oxygen-rich blood can be supplied to the entire heart muscle. The right coronary artery supplies blood mainly to the right side of the heart.
The adult human heart pumps about 30 litres of blood each minute, which is approximately 2,000 gallons of blood each day pumping throughout the body, in a non-stop cycle. The ability for the heart to remain healthy and to pump effectively can vary depending on the person’s age, size, the health of the individual person and thus on the condition of the heart.