Your heart is a hollow, muscular organ whose walls are composed of a special kind of muscle tissue: cardiac muscle. This tissue isn't found anywhere else in the body. The cells that compose this tissue pulsate of their own accord, without any outside stimulation. In fact, a heart removed from a human body will continue to beat.

There are four chambers in your heart. The right atrium and ventricle pump oxygen-depleted blood to the lungs through the pulmonary vessels. Newly oxygenated blood flows from the lungs into the heart's left atrium and ventricle. From there the blood is pumped to the body via the aorta, the largest artery in your body.

Your cardiovascular system consists of your heart, your blood vessels, and your blood itself. Blood is mostly made up of plasma and red and white blood cells. But it contains many other substances as well, like platelets, hormones, nutrients such as glucose, and lipids (fats) like cholesterol. Your cardiovascular system distributes these substances throughout your body as needed and collects waste products from your cells for elimination.

More on this topic

Understanding Heart Attacks (VIDEO)
Your Heart Needs Blood
Your Beating Heart
Atherosclerosis & Cholesterol
Angina & Coronary Heart Disease
Heart Attack Symptoms
What Is a Heart Attack?
Risk Factors & Diagnosis
Treating Heart Attacks
Restoring Blood Flow
Rehabilitation

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