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How does the cardiovascular system work?

The cardiovascular system, composed of the heart and blood vessels, is responsible for circulating blood throughout your body to supply the tissues with oxygen and nutrients. The heart is the muscle that pumps blood filled with oxygen and nutrients through the blood vessels to the body tissues. It is made up of:

Four chambers (two atria and two ventricles) that receive blood from the body (the atria) and pump out blood to it (the ventricles)
  • The right atrium receives blood from the body, which is high in oxygen and low in carbon dioxide.
  • The right ventricle pumps the blood from the right atrium into the lungs to provide it with oxygen and remove carbon dioxide.
  • The left atrium receives blood from the lungs, which is rich in oxygen.
  • The left ventricle pumps the blood from the left atrium into the body, supplying all organs with blood.
Blood vessels, which compose a network of arteries and veins that carry blood throughout the bod.
  • Arteries transport blood from the heart to the body tissues.
  • Veins carry blood back to the heart.

Four valves to prevent backward flow of blood

  • Each valve is designed to allow the forward flow of blood and prevent backward flow.
An electrical system of the heart that stimulates contraction of the heart muscle
To understand the cardiovascular system, we can follow the path of blood, beginning in the heart. The heart is divided into four chambers: the left and right atria and the left and right ventricles. The left ventricle pumps oxygen-rich blood out of the heart and into an artery called the aorta. From the aorta, blood branches out into a series of ever smaller tube-like vessels: arteries, arterioles, and finally capillaries. The capillaries deliver the blood's oxygen and nutrients to cells. Then the oxygen-poor blood makes the journey back: from capillaries, to vessels called venules, to veins, and finally back to the heart.

Before blood can begin its journey around the body again, it must travel to the lungs to release carbon dioxide and take in oxygen. The right atrium accepts the oxygen-poor blood and delivers it to the right ventricle, which pushes the blood through arteries to the lungs. The blood then returns through veins from the lungs to the left atrium then into the left ventricle, which pumps into the aorta again.

All components of the cardiovascular system are carefully balanced and interdependent. Because of this, when a problem arises in one part of the system, other areas may be affected as well. A person with narrowed coronary arteries, or coronary artery disease, is more likely to have narrowed arteries in the legs as well. (This is known as peripheral artery disease, or PAD.)

This is why diseases of the cardiovascular system put people at risk for a number of conditions, such as heart attack, stroke, kidney failure, and other serious illnesses.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.