Vein

Veins are a major part of the circulatory system. The circulatory system carries blood to various parts of the human body. Blood transports oxygen and removes waste. If veins are unhealthy, the heart will have difficulty pumping blood to different areas of the body. This can cause heart disease, embolisms, or a variety of other health problems.

However, proper diet and exercise can help keep veins healthy. A proper diet stops damaging plaque from building up in veins, arteries, and the heart, while exercise strengthens the circulatory system, helping the body become more efficient at transporting oxygen.

Background

The circulatory system carries oxygen to various parts of the body to help them function. It also takes waste away from those areas. The circulatory system is composed of the heart, veins, arteries, capillaries, and other parts. The heart pumps blood by shifting it through chambers called ventricles. Because the heart is composed of specialized muscle, it pumps independent of human control or thought.

The heart pumps blood through the lungs. The lungs take in oxygen and deposit it into the blood. This oxygenated blood is then pumped into arteries, which carry the blood throughout the body. Once the oxygen from the blood is carried to various parts of the body, the blood shifts into the veins. Veins transport the deoxygenated blood back to heart, and the process beings all over again.

The circulatory system is one of the most important anatomical systems in the human body. If oxygenated blood cannot flow to organs and muscles groups, those parts of the body will quickly cease to function. If the heart stops pumping blood through the body, or if the flow of blood is blocked, the results can lead to serious illness or death.

Overview

Veins are a major component of the circulatory system. They bring deoxygenated blood back to the heart and lungs, where oxygen is restored to the blood and then sent back through the body. To complete this process, the veins work in conjunction with the heart, arteries, and capillaries.

Along with the rest of the circulatory system, veins function without conscious direction from the human mind. Most people have no control over how their body pumps blood. Other processes in the human body, such as digestion and respiration, also function in this manner.

The circulatory system contains three types of veins: superficial, deep, and perforating veins. Superficial veins are the veins closest to the skin. They can often be seen on people with especially pale skin. Although there are many of these veins, superficial veins are responsible for carrying only about 10 percent of the blood in the body back to the heart. Perforating veins form a complex web that connects superficial veins to deep veins. Deep veins are more powerful veins found inside the body's muscles. They are responsible for carrying the vast majority of the body's deoxygenated blood back to the heart.

Veins come in a variety of sizes. Perforating and superficial veins are smaller than deep veins and carry a significantly smaller portion of the body's blood supply. The largest vein in the body, the vena cava, is located just above the heart. It is often referenced as two parts—the superior vena cava and the inferior vena cava. The superior vena cava returns blood from the head, neck, and upper body to the heart. The head and neck require a large percentage of the body's blood supply to function properly, making the superior vena cava incredibly important. The inferior vena cava restores deoxygenated blood from the rest of the body to the heart.

In addition to carrying blood back to the heart, veins also need to be able to temporarily stop blood from flowing. When a person is standing, the heart is not strong enough to pump against gravity. It can send blood down through the body, but only partway back up. To allow blood to return to the heart, veins can clamp down, stopping blood from flowing back down. They accomplish this by constricting at key points, trapping the blood between two constricted areas. When the heart pumps again, the blood is pushed forward through another segment of veins.

To carry blood throughout the entire body, veins needs to be flexible. They must bend and stretch with the body's muscles as they move. A healthy diet and regular exercise will keep both veins and arteries flexible and strong. In contrast, a diet high in cholesterol can lead to a buildup of plaque inside veins and arteries. This stiffens and narrows them, making it much harder for blood to pass through. When the problem grows severe, the heart will strain to force blood through the narrowed veins and arteries. Over time, this can cause severe heart disease.

Several deadly diseases can result from unhealthy veins. For example, deep vein thrombosis is a disease in which a blood clot forms in the large, deep veins of the lower body. Symptoms include pain, warmth, and redness near the area of the clot. Deep vein thrombosis can lead to a pulmonary embolism, an artery blockage in the lungs. Pulmonary embolisms can become life-threatening if they are not quickly diagnosed and treated. Chronic vein disease can also cause varicose veins, prominent places in the body where veins have become swollen, overfilled with blood, or dilated. Varicose veins appear as red or purple veins that have pushed up toward the surface of the skin. Blood can become trapped in varicose veins, causing them to become extremely painful. They are most often found in the lower legs, where gravity makes it most difficult for blood to flow upward.

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