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Overview of the Vascular System

What is the vascular system?

The vascular system, also called the circulatory system, is made up of the vessels that carry blood and lymph through the body. The arteries and veins carry blood throughout the body, delivering oxygen and nutrients to the body tissues and taking away tissue waste matter. The lymph vessels carry lymphatic fluid (a clear, colorless fluid containing water and blood cells). The lymphatic system helps to protect and maintain the fluid environment of the body by filtering and draining lymph away from each region of the body.

Collectively, the blood and lymphatic systems are the transport systems of the body. They supply oxygen, nutrients, removal of waste products, fluid balance, as well as many other functions, to all organs and tissues of the body. Therefore, conditions that affect the vascular system may affect the organs supplied by a particular vascular network such as the coronary arteries of the heart, for example. A blockage in the coronary arteries of the heart may cause a heart attack.

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The vessels of the blood circulatory system are:

• arteries - blood vessels that carry oxygenated blood from the heart to the body.

• veins - blood vessels that carry blood from the body back into the heart.

• capillaries - tiny blood vessels between arteries and veins that distribute oxygen-rich blood to the body.

Blood moves through the circulatory system as a result of being pumped out by the heart. Blood leaving the heart through the arteries is saturated with oxygen. The arteries break down into smaller and smaller branches in order to bring oxygen and other nutrients to the cells of the body's tissues and organs. As blood moves through the capillaries, the oxygen and other nutrients move out into the cells, and waste matter from the cells moves into the capillaries. As the blood leaves the capillaries, it moves through the veins, which become larger and larger to carry the blood back to the heart.

In addition to circulating blood and lymph throughout the body, the vascular system functions as an important component of other body systems. Examples include:

• respiratory systemAs blood flows through the capillaries in the lungs, carbon dioxide is given up and oxygen is picked up. The carbon dioxide is expelled from the body through the lungs, and the oxygen is taken to the body tissues by the blood.

• digestive systemAs food is digested, blood flows through the intestinal capillaries and picks up nutrients, such as glucose (sugar), vitamins, and minerals. These nutrients are delivered to the body tissues by the blood.

• kidneys and urinary systemWaste materials from the body tissues are filtered out from the blood as it flows through the kidneys. The waste material then leaves the body in the form of urine.

• temperature controlRegulation of the body's temperature is assisted by the flow of blood among the different parts of the body. Heat is produced by the body's tissues as they go through the processes of breaking down nutrients for energy, making new tissue, and giving up waste matter.

What is vascular disease?

A vascular disease is a condition that affects the arteries, veins, or lymphatic vessels. Most often, vascular disease affects blood flow, either by blocking or weakening blood vessels, or by damaging the valves that are found in veins. Organs and other body structures may be damaged by vascular disease as a result of decreased or completely blocked blood flow.

What causes vascular disease?

Causes of vascular disease include:

• atherosclerosisAtherosclerosis (a build-up of plaque, which is a deposit of fatty substances, cholesterol, cellular waste products, calcium, and fibrin in the inner lining of an artery) is the most common cause of vascular disease. Atherosclerosis is a slow, progressive, vascular disease that may start as early as childhood. However, the disease has the potential to progress rapidly. It is generally characterized by the accumulation of fatty deposits along the innermost layer of the arteries. If the disease process progresses, plaque formation may take place. This thickening narrows the arteries and can decrease blood flow or completely block the flow of blood to organs and other body tissues and structures.

• embolus/thrombusA blood vessel may be blocked by a thrombus (a bloot clot) or an embolus (typically a thrombus that moves through the bloodstream).

• inflammationIn general, inflammation of blood vessels is referred to as vasculitis, which includes a range of disorders. Inflammation may lead to narrowing and/or blockage of blood vessels.

• trauma/injuryTrauma or injury involving the blood vessels may lead to inflammation or infection, which can damage the blood vessels and lead to narrowing and/or blockage.

What are the effects of vascular disease?

Because the functions of the blood vessels include supplying all organs and tissues of the body with oxygen and nutrients, removal of waste products, fluid balance, and other functions, conditions that affect the vascular system may affect the part(s) of the body supplied by a particular vascular network, such as the coronary arteries of the heart.

Examples of the effects of vascular disease include:

• coronary artery disease - heart attack, angina (chest pain)

•  cerebrovascular disease - stroke, transient ischemic attack (a sudden or a temporary loss of blood flow to an area of the brain, usually lasting less than five minutes but not longer than 24 hours, with complete recovery)

• peripheral artery disease - claudication (pain or discomfort in the thigh, calf, and/or buttocks that occurs when walking), critical limb ischemia (lack of adequate blood supply to the limb/leg at rest)

• aneurysm - a bulging, weakened area in the wall of a blood vessel resulting in an abnormal widening or ballooning of the aorta (narrowing of the aorta, the largest artery in the body)

  • thoracic aortic aneurysm - a bulging, weakened area in the wall of a blood vessel resulting in an abnormal widening or ballooning in the thoracic, or chest, portion of the aorta

  • abdominal aortic aneurysm - a bulging, weakened area in the wall of a blood vessel resulting in an abnormal widening or ballooning in the abdominal portion of the aorta

  • peripheral aneurysm - bulging, weakened area in the wall of the blood vessel resulting in an abnormal widening or ballooning of an artery in the extremities

• deep vein thrombosis (DVT) - a blood clot in a deep vein located within the muscles of the leg

•  varicose veins - a bulging or weakened area in the wall of a superficial vein, just under the skin

• lyphedema - swelling caused by interruption of the normal drainage pattern in the lymph nodes

• renal (kidney) artery diseases - renal artery stenosis (blockage of a renal artery) caused by atherosclerosis or fibromuscular dysplasia (a condition that weakens the walls of medium-sized arteries and occurs predominantly in young women of childbearing age)

Because vascular conditions and diseases may involve more than one of the body's systems at a time, many types of physicians treat vascular problems. Specialists in vascular medicine and vascular surgery work closely with physicians in other specialties, such as internal medicine, interventional radiology, cardiology, and others to ensure comprehensive care of patients with vascular conditions.

Click here to view theOnline Resources of Cardiovascular Disease