Cardiac Anatomy
Introduction:
The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of a clenched fist. By the end of a long life heart may beat (expanded and contracted) more than 3.5 billion times. Each day, the average heart beats 100,000 times, pumping about 2,000 gallons (7,571 liters) of blood. It is located between both lungs in the middle of the chest, behind and slightly to the left of sternum. A double-layered membrane called the pericardium surrounds the heart like a sac. The outer layer of the pericardium surrounds the origins of the heart's major blood vessels and is attached by ligaments to the spinal column, diaphragm, and other parts of the body. The inner layer of the pericardium is attached to the heart muscle. A coating of fluid separates the two layers of membrane, letting the heart move frictionless as it beats.
It has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. Muscular wall which separates the left and right atria and the left and right ventricles is called atrial and ventricular septum respectively. The left ventricle is the largest and strongest chamber in the heart.