The double-walled membrane houses the pericardial fluid which cushions the heart preventing shock and nourishing it. Its divided into four chambers and has a large network of arteries and veins. The chambers are known as the atrium and ventricles. A special kind of muscle called the septum divides the right cavity and the left cavity. Normally the expulsion of blood from one cavity would result in a subsequent amount of blood flowing into the adjacent cavity.
The left ventricle is the strongest and largest chamber since its tasked with pumping blood to all parts of the body through the aorta. The right cavity of the heart which is composed of the right atria and right ventricle receives deoxygenated blood from all parts of the body and pumps this blood to the lungs for oxygenation (pulmonary circulation). The left cavity composed of the left atria and left ventricle receives the oxygenated blood from the lungs and pumps this blood to all body parts through the aorta (systemic circulation).
The heart has four valves that regulate the flow of blood through its chambers. Blood flow from the right atrium to the right ventricle is regulated by the tricuspid valve. The pulmonary valve regulates blood flowing into the pulmonary artery from the right ventricle. Oxygenated blood from the lungs passes through the mitral valve situated between the left atrium and left ventricle.
The aortic valve regulates oxygenated blood flow from the left ventricle to the aorta for delivery to the body. One of the greatest threats to the hearts proper functioning and subsequently to a persons survival is a heart attack. A heart attack occurs when the heart is not able to pump blood effectively due to arteries clogging. Deposition of fatty cells in arteries will lead to their constriction inhibiting the flow of blood leading to a heart attack which is fatal in most cases.