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Circulatory System
The heart, blood, and blood vessels make up the cardiovascular component of the circulatory
system. It includes the pulmonary circulation, a "loop" through the lungs where blood is oxygenated. It
also incorporates the systemic circulation, which runs through the rest of the body to provide
oxygenated blood.
The pulmonary circulatory system sends oxygen-depleted blood away from the heart through
the pulmonary artery to the lungs and returns oxygenated blood to the heart through the pulmonary
vein.
Oxygen-deprived blood enters the right atrium of the heart and flows through the tricuspid
valve (right atrioventricular valve) into the right ventricle. From there it is pumped through the
pulmonary semilunar valve into the pulmonary artery on its way to the lungs. When it gets to the lungs,
carbon dioxide is released from the blood and oxygen is absorbed. The pulmonary vein sends the
oxygen-rich blood back to the heart.
The systemic circulation is the portion of the circulatory system is the network of veins, arteries
and blood vessels that transports blood from heart, services the body's cells and then re-enters the
heart.
Diseases of the circulatory system
According to the American Heart Association, cardiovascular disease is the leading cause of
death in the United States. Because of its vastness and critical nature, it is one of the systems of the
body most prone to disease.
One of the most common diseases of the circulatory system is arteriosclerosis, in which the
fatty deposits in the arteries causes the walls to stiffen and thicken the walls. The causes are too much
fat, cholesterol and calcium. This can restrict blood flow or in severe cases stop it all together, resulting
in a heart attack or stroke.
Another circulatory is disease, hypertension — commonly called high blood pressure — causes
the heart to work harder and can lead to such complications as a heart attack, a stroke, or kidney failure.
An aortic aneurysm occurs when the aorta is damaged and starts to bulge or eventually tear,
which can cause severe internal bleeding. This weakness can be present at birth or the result of
atherosclerosis, obesity, high blood pressure or a combination of these conditions.