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 protect and maintain the fluid
environment of the body by filtering and draining lymph away from each region of the
The vessels of the blood circulatory system are:
Arteries. Blood vessels that carry oxygenated blood away 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 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 system. As 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 system. As 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 system. Waste 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 control. Regulation 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 and veins. 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
What causes vascular disease?
Causes of vascular disease include:
Atherosclerosis. Atherosclerosis (a buildup 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. It is unknown exactly
how atherosclerosis starts or what causes it. 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 buildup of fatty
deposits along the innermost layer of the arteries. If the disease process progresses,
plaque may form. 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.
Blood clots. A blood vessel may be blocked by an embolus (a tiny mass of debris that
moves through the bloodstream) or a thrombus (a blood clot).
Inflammation. In general, inflammation of blood vessels is referred to as vasculitis,
which includes a range of disorders. Inflammation may lead to narrowing and blockage
of blood vessels.
Trauma or injury. Trauma or injury involving the blood vessels may lead to inflammation
or infection, which can damage the blood vessels and lead to narrowing and blockage.
Genetic. Certain conditions of the vascular system are inherited.
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 temporary
loss of blood flow to an area of the brain, usually lasting less than 5 minutes but
not longer than 24 hours, with complete recovery)
Peripheral arterial disease. Claudication (limping because of pain in the thigh, calf,
and/or buttocks that occurs when walking), critical limb ischemia (lack of oxygen
to the limb/leg at rest)
Vascular disease of the great vessels. Aortic aneurysm (a bulging, weakened area in
the wall of a blood vessel resulting in an abnormal widening or ballooning), coarctation
of the aorta (narrowing of the aorta, the largest artery in the body), Takayasu arteritis
(a rare inflammatory disease affecting the aorta and its branches)
Thoracic vascular disease. 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 vascular disease. 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 venous disease. Deep vein thrombosis (also called DVT; a blood clot in
a deep vein located within the muscles of the leg), varicose veins
Lymphatic vascular diseases. Lymphedema (swelling caused by interruption of the normal
drainage pattern in the lymph nodes)
Vascular diseases of the lungs. Wegener granulomatosis (an uncommon disease in which
the blood vessels are inflamed; mainly affects the respiratory tract and the kidneys),
angiitis (inflammation of blood vessels), hypertensive pulmonary vascular disease
(high blood pressure in the lungs' blood circulation due to vascular conditions)
Renal (kidney) vascular diseases. Renal artery stenosis (blockage of a renal artery),
fibromuscular dysplasia (a condition that weakens the walls of medium-sized arteries
and occurs predominantly in young women of childbearing age)
Genitourinary vascular diseases. Vascular erectile dysfunction (impotence)
Because vascular conditions and diseases may involve more than one of the body's systems
at a time, many types of doctors treat vascular problems. Specialists in vascular
medicine and/or surgery work closely with doctors in other specialties, such as internal
medicine, interventional radiology, cardiology, and others to ensure comprehensive
care of patients with vascular conditions.