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The
Circulatory System
The
blood vessels that comprise the vascular system
are part of the circulatory, or cardiovascular,
system. The heart is the major organ of this system.
With each beat, it pumps blood into the vessels
and through the body, bringing oxygen and other
nutrients necessary to the life to the cells.
As the blood circulates, it also removes waste
products, toxins and other harmful substances.
The circulatory system works with many other systems.
It plays an especially important role in:
* The Respiratory System. Blood circulates through
the lungs where it exchanges carbon dioxide and
oxygen.
* The Digestive System. Blood circulates through
the intestines where it absorbs nutrients from
food that was eaten and digested.
* The Excretory System. Blood circulates through
the kidneys which filter out wastes that are removed
from the body in the urine.
* Temperature Control. As the blood flows, heat
moves back and forth between the blood and the
cells. This constant exchange of heat keeps all
the body parts at the same temperature. This explains
why people with circulatory problems often have
cold feet or hands, or spots where the skin is
warm to the touch.
The
Blood Vessels
There
are three types of vessels that aid in the transport
of blood, and in keeping it in constant circulation
from the heart to the body, and back to the heart:
* Arteries
* Veins
* Capillaries
The
blood vessels are more than simple tubes through
which blood flows. Each has its own characteristics,
depending on the role it plays in the circulatory
system.
Arteries
are strong, flexible blood vessels that must expand
to accept the blood pumped into them with each
beat of the heart, and contract to squeeze blood
into the veins when the heart relaxes.
Veins
The
veins that return blood to the heart are less
“active” and elastic than the arteries.
Veins have valves that open to let blood through,
and close to prevent blood from pooling in the
legs and elsewhere due to the pull of gravity.
There are three types of veins:
Superficial
veins lie near the surface of the skin. Larger
veins that usually are buried in the muscles or
deep compartments of the body are called Deep
Veins. Blood vessels that connect the superficial
and deep veins are called “communicating”
or Perforating Veins. |
Capillaries, which look more like webs than vessels
or tubes, lie in tangled “beds” in the
tissues of the body. They are so tiny that blood
cells must pass through them in single file. The
exchange between the blood and the cells of the
body takes place in the capillary beds. Here, blood
takes oxygen from the cells and gives up carbon
dioxide. Special capillaries in the kidneys, liver
and elsewhere take waste products that are excreted
from the body. As |
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capillaries spread out of their beds, they thicken
and merge into small vessels called “venules”
that, in turn, lead to larger veins that return
blood to the heart. |
Preventing Vascular Disease
The
best way to prevent vascular disease is to live
a “heart healthy” lifestyle –
don’t smoke; eat nutritious, low fat foods;
exercise; control risk factors and maintain a
healthy weight.
Life
style changes. The single most effective steps
you can take to prevent vascular disease are to
quit smoking and control high blood pressure,
high cholesterol, diabetes and other factors that
contribute to vascular disease. Regular exercise,
eating a balanced diet and maintaining a healthy
weight also are important.
Types
of Vascular (Blood Vessel) Disease
Most
vascular diseases are caused by conditions that
clog or weaken blood vessels, or damage valves
that control the flow of blood in and out of the
veins. Most vascular disease is caused by arteriosclerosis,
often called “hardening of the arteries”
(although veins also can be affected).
In
this condition, a sticky substance called "plaque"
builds up inside the blood vessels. Over time,
the blood vessels may weaken or become so clogged
that the blood supply to affected parts of the
body is reduced or blocked. The flow of blood
also may be affected when a blood clot (thrombus)
gets stuck in a blood vessel.
Arterial
Disease and Venous Disease |
It
is called "arterial disease" when arteriosclerosis,
blood clots and other vascular conditions occur
in the arteries. Problems that occur in the veins
are called “venous disease.” Some
vascular conditions occur only in arteries, others
are unique to the veins. Some can affect either
type of vessel, such as aneurysms and arteriovenous
malformations (AVM) (abnormalities in the brain
or elsewhere in which the blood vessels are tangled
and distended). Aneurysm and AVMS are called “silent
killers” because they often produce no symptoms
until they rupture.
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Aneurysms
are weakened areas in the blood vessels that bulge
like balloons when blood flows through them. Once
they grow to a certain size, there is a risk of
rupture and life-threatening bleeding. |
Arterial Disease
Common
diseases affecting the arteries include:
* Peripheral vascular disease (PVD) (sometimes
called peripheral arterial disease, or PAD) is
a condition where the arteries that carry blood
to the legs (and, less frequently, the arms) become
narrow or clogged.
* Carotid artery disease is a condition in which
the arteries in the neck that supply blood to
the brain become clogged and may cause a stroke.
* Abdominal aortic aneurysm (AAA), or Triple A,
is an area in the main artery of the heart (the
aorta) that is weakened and bulges like a balloon.
If it grows large enough, the aneurysm can rupture
and cause life-threatening bleeding. Males over
the age of 60 who smoke or have ever smoked and
people with a history of AAA in their family are
at highest risk for this disease. |
Courtesy of Society of Interventional Radiology
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